Livro com projetos de eletrônica direcionado para músicos

2. Preface
ChapterOne If you don't know what a resistoris, don't know how to reada schematic,and
wouldn't knowa 10JJFcapacitorif you collided with one, Chapter1 is for you. <)
10
11
14
A Little Theory
Resistors
Potentiometers
Capacitors
Semiconductors
Wire
MechanicalParts
ReadingSchematicDiagrams
SubstitutingParts
TableoCElectronicMeasurements
18
24
27
28
ChapterTwo 29
29
29
30
31
~1
A surveyo[ howandwhereto /ind partsat reasonableprices.
FindingMail-OrderPartsSources
FindingandBuyingfrom LocalPartsSources
Gettingthe Mostout of Mail Order
Gettingthe DestPrices:StockingYour Lab
PartsKits
Chapter Three Beforeyou do any building, you needtoo/sand a know/edgeof how to carefor
them. This chaptercoversdril/s, hacksaws,fi/es, p/iers, cutters, strippers,screw-
drivers,so/deringequipment,p/exig/asstoo/s,careoftoo/s, andsafetytips. 34
ChapterFour II you haveneverbuilt anything electronicbelore, Chapter 4 will help you out
considerably.It tells you what you needto know to tum a pile ol parts into an
attractive,reliable,smoothlylunctioning unit. 1Q
39
39
40
41
44
45
47
51
53
54
55
56
,7
Introduction
SoIdeñng Technique
Desoidering
The Careand Feeding of Pñnted Circuit Boards
Perfboard Construction
Loading the Circuit Board
Se³ectingan EncIosure
Dñ³ling
Genera³Wiñng
Grounding
Wiñng the Circuit Board to Outboard Parts
ShieIded rabie
Mounting the Circuit Board in the Enc³osure
Add the Knobs and Labe³ the Functions
Testing and Checking out Performance

3. ChapterFive Wefirst discusssomeimportant instructions
thecompletestory on building27projects.
'mmonto a/l vro;ec
:8
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62
63
69
_¥
86
90
94
99
104
110
113
138
142
149
154
160
168
"'7"
Format
Line Levelor Low Level
ConnectingPowerto the Projects
ProperCareof theCLM6000
JumperWires
TransistorOrientation
ProjectNo. I-Preamp
ProjectNo. 2-Metronome
ProjectNo. 3-PassiveToneControl
ProjectNo. 4-HeadphoneAmp
ProjectNo. S-Miniamp
ProjectNo. 6-Ultra-Fuzz
ProjectNo. 7-BassFuzz
ProjectNo. 8-Compressor/Limiter
ProjectNo. 9-Ring Modulator
ProjectNo. lO-Dual Filter VoicingUnit
ProjectNo. II-Adding BypassSwitchesto Effects
ProjectNo. 12-Guitar Rewiring
ProjectNo. 13-Bipolar AC Adapter
ProjectNo. 14-Treble Booster
ProjectNo. IS-Electronic Footswitch
ProjectNo..16-Tuning Standard
ProjectNo. 17-Super ToneControl
ProjectNo. 18-Eight in, Oneout Mixer
ProjectNo. 19-Using aVolt Ohm-Milliammeter
ProjectNo. 20-PracticePlayAlong
ProjectNo. 21-PhaseShifter
ProjectNo. 22-Making PatchCords
ProjectNo. 23- Talk Box
ProjectNo. 24-Tube SoundFuzz
ProjectNo. 2S-EnvelopeFolIower
ProjectNo. 26-Spluffer
ProjectNo. 27-Noise Gate
180
Chapter Six Now thal
advanta~e
i¿e'uilt al! the usethem tc
96
96
96
Q7
Introduction
The Different Waysof Connecting Effects
PackagingMultiple Effects Systems
Distributing rower to the Modules
Impedance Matching
A Typical Effects System
Effects Format
Modifications to the BasicSystem
Additional Effects Systems

4. Chapter Seven At somepoint, somethingyou build isn't going to work right. Thischapteris de-
signedto helpyou Ketit working. 201
Chapter Eight 204Waysto learn more about musical electronics.
205
205
205
207
208
208
208
208
209
WhatDoesWork?
People
Magazines
Books
Libraries
SemiconductorManufacturers'DataBooks
"Hands-on"Waysto LearnElectronics
Kits
Correspondence
ChapterNine 210Questions and answers.
Appendixes 215
215
About the Soundsheet
How the SoundsheetWasRecorded
219Glossaryot Terms UnderstandingSpecifications
220About the lIIustrator

5. As of this date,tensof thousandsof musicians-manywilli no prior experiencein electronics
-have takencontrol of their sound,by buildingelectronicmodifiersfrom the fust edition of
this book. Beginnersshouldbe happy to know that the instructionalmaterialfrom the fust
edition hasbeen left intact, and in somecaseshasbeenexpanded.Thosewho havethor-
oughly absorbedthe information in the fust edition will bepleasedto find anumberof new
andimprovedprojects,aswell asadditionalinformation on creatingpedalboardsandmulti-
ple effects systems,explanationson the theory of operation of the variousprojects,and
warg to modify them for customizedperformance.So,while this newedition wasstill ex-
presslywritten willi beginnersin mind, I believethereisenoughadditionalmaterialto hold
the musician'sinterest evenafter he or shehaspassedthe introductory stageof leaming
aboutthis art.
Oneof the questionsI consistentlyhearis,"But caDI really build this stuff, eventhough
I know nothing about electronics?"The answeris yes.My files arefilled with lettersfrom
people who expressamazementand delight at havingbuilt a high-t.echnologydevice,by
themselves,without aDYproblems.If they cando i³, if I caDdo it (rememberI wasODcea
beginnertoo!), thenyou caDdo i³.
Why do it yourself? Perhapsa better questionis why not do it yourself.Whileyou gen-
erally savemoneycomparedwilli buying a commerciallyavailabledevice,you algohavethe
satisfactionof creatingsomethingwith your owo two hands,andyou leamenoughabout
the project in the processof building it so that you caDmodify it to suityour exactneeds.
A lesstangible,but perhapsmoreiroportant,advantageis the increasein self-confidencethat
comesfrom knowing that you caDmake senseout of all thosewiresand parts,and tum
them into a useful, working project. I've known numerouspeoplewho thought they'd
neverunderstandthis stuff; but whenthey do, they feelalittle better aboutthemselvesand
their abilitiesbecauseof i³.
It took longerto rewritethisbook thanit did to write it in the fust place,mostlybecause
I wantedthe projectsto beequalto-and, if possible,superiorto-other, comparabledevices
availableon the market.Thishasmeantthat generally,the projectsaresomewhatmorecom-
plex than thosepresentedin the fust book;however,overtheyearsI've foundthat anybody
who caDsuccessfullybuild a project with one IC and ten other partscaDalgosuccessfully
build aprojectwith two ICsandtwenty otherparts.Therearestill anumberof introductory
projects,essentiallyunchangedfrom the fust edition, for thosewho preferto startorf with
somethingreally simple.
In ciosing,I'd like to thank severalpeoplewho otherwisemight not get the recognition
they deserve.First is VestaCopestakes,aconstantsourceofinspiration andavery fiDeillus-
tratorjphotographer;Jiro Crockett, publisherof Guitar Player magazine,who fust recog-
nizedtheneedfor abook like this; Bill Godbout,for histechnicalassistance;BruceMycroft,
for laying out the circuit boardsso I could spendall my time writing; andthe peopleat
MusicSales(my publisher),who didn't hassIeme or tfY to speedmeup whenI kept asking
for more time to makethis manuscriptasgoodasI couldpossiblymakeit. Finally (savethe
best until last), thanks to all the peoplewho enjoyedthe fust edition of this book-your
support andyour commentsarethe reasonwhy this revisededition exists.May your proj-
ectsalwayskeepworking!
...

6. If you don't know what a resistor is,
don't know how to reJd a schematic,
and wouldn't knowa 1°/.LFcapacitorif
you collidedwith one, Chapter 1 is for
you.
ALIttle Theory rather than just dealing with the number of electrons
going down a conductor. With OUTautomobile analogy,
voltage would be equivalent to the speedof the car in
mph. A condition in a circuit where there is no voltage
present is referred to as ground, or minimum possible
intensity (zero volts-the volt, abbreviated V, measures
voltage). There are still just as many electrons hanging
around; but they have no intensity, and don't do any-
thing. A moce intense level of activity trans1atesinto
higher voltage.
What provides this intensity? Well, in electrical circuits
you need an area that Iacks electrons and wants to ac-
quire some, and an ar-êathat has a surplus of electrons.
(The best example of this is a battery: one terminal is
loaded with electrons just waiting to get out and do
their number, whereas the other terminal is begging to
have eIectrons come in.) The intensity with which the
electrons want to get from one end to the other is .the
voltage. The medium through which the electrons make
their joumey from one areato another is the conductor.
This brings us to resistance. The reasonfor resistance
is that when the electrons tfY to get from one areato the
other through the conductor, they are always trying to
move as quickly as they caD, and you have to control
them in some way. AlI conductors represent a certain
amount of resistance, since no conductor is 100 percent
efficient. To control eIectron flow in a predictable man-
ner, you use resistors; these are electrical parts similar to
conductors, but which resist to a greater or lesserextent
the flow of current. Putting one in line with a conductor
is like putting up a 50-mph ZOfiein the middle of a high-
way: the energy Ievel decreases,yielding a moce con-
trolle d flow. The resisting ability of a resistorisexpressed
in ohms (named after GeorgSimon Ohm, aGermanphysi-
cist of the 1800s and abbreviated by the Greek letter
omega, Q), and caD cover a wide range. Ten million
If you really want to get into theory, libraries,book
stores,and electronic storesall havebooksabout basic
electronics.But for now, let's simply take a quick look
at four important concepts:voltage,current, resistance,
andcapacitance.You don't really haveto understandit
all just ret; the important thing is to get a feel for the
language.
Electricity is all about the motion of electrons.Elec-
transareall overthe placeascomponentpartsof atoms,
but whenthey'relocatedinsidethe atomsof certainma-
terialsknown asconductors(like wiTe,or othermetals),
you canplay gameswith ³bem.Actually, themotion of
electronsin a conductoris a lot like traffic flow downa
freeway.WiTeis sort of afreewayfor electrons;electrons
arelike little cars.If a bunch of carsaresitting in the
middleof a highwayout of gas,not muchishappening.
But give³bemalittle energy,direct ³bem(i.e., star to the
right, passon the left, stopat redlights),andyou'vegot
anactivefreeway.Samewilli electrons:give³bemsame
energy,tell ³bem what to do, and you've got an active
conductor,which is the first steptoward an activecir-
cuit. The oppositeof a conductoris calledaninsulator,.
ratherthan encouragingthe flow of electrons,it inhibits
the flow, muchasremovinga sectionof highwayguaran-
teesthat no carsaregoingto be travelingoverthat par-
ticularsection.
Current is analogousto the number of carsgoing
down the road. Just as bumper-to-bumpercars mean
heavytraffic, bumper-to-bumperelectron flow is con-
sideredheavycurrent.Themeasurementunit for current
is the ampere(amp or A for short), namedafter the
FrenchscientistAndr~MarieAmpere.
Voltageis a somewhatmaTeelusivephenomenonto
explain. It relates to the intensity of electron flow,
9

7. (or, how much it canvary from its statedvalue)of the
resistor. A silver band indicates³O%accuracy;a go³d
band,5%.The other threebandsrepresentthe value,in
ohms.of the resistor.
Figure1.:
ohms will tum an electrical stream into a trickle, where-
as 4 n won't slow things down much at all (that's why
speakershave a law resistancevalue; you want as many
electrons aspossible to go through the speakerand move
the paper cone back and forth to make things laud).
A close relative of resistanceis impedance. Impedance
is a measurement that's useful in analyzing the perform-
ance of audio circuits; just as resistance tells you some-
thing about how electrical current flows through a cir-
cuit, impedance tell syou how audio signalsflow through
a circuit. To completely understand impedance takes
some doing, since we're dealing with a pretty complex
subject; sa, aside from same additional information on
impedance in the section, "Understanding Specifications:
Glossary of Terms" at the end of this book, we won't
delve into this any further.
There's one other word that needsexamination while
we're talking about theory: capacitance.Capacitors stare
energy as their primary talent; they are made of twa
metal plates, separated by a thin insulator. Connecting a
voltage sourceto theseplates createsan electric field bet-
ween ³bem. Storing energy in this field is called charging
a capacitor, whereasdrawing the energyout (say,through
a conductor or resistor) is called discharging. This charge-
discharge action allows a current to flow, even though
the plates are insulated. Due to this property of a capaci-
tor to react to altemating (charging and discharging) cur-
rent, or AC, capacitors are frequently used to block di-
rect current (DC, the kind that stays steady, like from a
battery) but let altemating audio-type signals through.
More capacitance indicates more energy storage capabi-
lity.
Reslstors
By far, the most common resistor you'll encounter is
the carbon-composition type (so called because it's
mostly made up of carbon materials), shown in Figure
l-l. They ale smalI [6-12 mm (1/4 -1/2") long, by
3.6 mm (1/8 -1/4") wide], brown or tan cylinders with
.colored bands going around them. If you take a look in-
side any electronic equipment, you'll seea whole bunch
of resistors. In some cases,you'll seemetal-film resistors
as opposed to the standard carbon composition type.
These ale usually somewhat smaller than carbon types,
and ale lighter in color.
The most striking feature of a resistor is the four
color bands. These bands form a code which indicates
the approximate value of the resistor. The reason I sar
"approximate value" is becauseprecise resistancevalues
ale generally not that critical in electronic circuits (re-
member the speedZOfieanalogy given earlier: very rarely
do you seea 33.7-mph speedlimit, since 35 mph is close
enough). One of the bands will be either gold or silver;
this one, called the fourth band, indicates the tolerance
Eachnumberfrom zeroto nine is assigneda color: O
= black, l = brown, 2 = red, 3 = orange,4 = yellow, 5 =
green,6 = bIlle, 7 = violet, 8 = gray,9 = wbite. Now,the
first bandis the first digit of the resistorvalue,the sec-
and band is the seconddigit of the resistorvalue,and
the third bandis thenumberot zerosthat follow thefirst
twa digits.
Sa, if you havea resistorthat reads"blue-gray-red-
silver," that meansthe first digit is bIlle, or 6; the sec-
and digit is gray, or 8; and the red band meansthat
twa zerosfollow the first twa digits. Putting it alI to-
gether,you get 6-8-00,or 6800n. Thesilverbandindi-
catesthat the real-worldvalueiswithin 10%of 6800n.
Another example: brown-black-green7g01d.This de-
codesto first digit l, seconddigit O,and five zeros.So
you have1-0-00000,or 1,000,000n The'gold bandin-
dicatesthat the realvalueis within 5%of 1,000,000n.
To simplify matters,therearecertainstandardresis-
tor values.The first two digits of any 10%tolerancere-
sistorwill be oneof the followingcombinations:10, 12,
15, 18,22,27,33,39,47,56,68,82. Fore~ample,you
won't run acrossa 19,000n, 10%resistor,nor will you
seea 350 n one, becausethe first twa digits are not
standard10%values.
Sothat electronicspeopledon't spendalargeportion
of their time drawingzerosin resistorvalues,there are
twa commonlyusedabbreviations:kand M. k standsfor
a thousand,and M a million-a 22,000 n resistor,for
example,is commonlycalleda22k resistor.A 1,000,000
n resistoris called a 1M resistor,a 2,200,000n resis-
tor is calleda 2.2M resistor.The abbreviationk wasde-
rived from the somewhatlonger kilohm, which you'll
sometimesseein print; you'll also sometimesseemeg-
ohmor Meginsteadof the simplerM.
Schematicsfrom Europe,andmostotherpartsof the
world, abbreviateresistorsvaluesalit tle differently from
10

8. Americanschematics;when a resistorvalueincludesa
decimalpoint (i.e., 2.7k, 1.2M), the kor Mis inserted
wherethe decimalpoint would normally appear.Here
are sameexamplesof Americannomenclatureand the
metricequivalents:
Ameñcan Metric
2.7k 2k7
4.7k 4k7
2.2M 2M2
5.6M 5M6
Figure1-2
1/4W resistor
1/2W resistor
==:(
1W resistor
. .
,i. 7K 1% """('
metal film, precisionresistor
@ ~
10W power resistor
If thereis no decimalpoint in the resistorvalue,then
the metric and Americandesignationsarethe same( n
isusedin both Americanandmetric systems).
In addition to the statedvaluein ohms,anothercon-
cero of resistorsis how muchheat they caDhandle.In
the processof slowingdown electricalenergy,the dis-
sipatedenergybas to go somewhere-itgenerallytums
iG³obeat. Resistorsare rated in watts (abbreviatedW),
the unit of power, in regardto their ability to handle
beat.For example,a 2WresistorcaDhandlemorepower
than a IW type. However,the projects in this book
aren't involvedwith heavycurrents,sowe'll mostly be
usingI/4W resistors.Thesehavethe advantageof being
physically smallerthan I/2W resistors,the other most
populartype. You caDalwaysusea Iargerwattageresis-
tor than the one specifiedif there'sroom,but neveruse
a smallerresistor.An underratedresistorcaDoverheat,
thuschangingits valueandpossiblydamagingthe circuit
to whichit connects.
Figure 1-2 Showssameother types of resistorsyou
mayrun acrossin electronicdevicesfrom time to time,
suchaspowerresistors(not just IW - sometimes10-or
2aWin berty power supplies);precisionresistors(where
you need an exact resistancevalue,and 5% tolerance
isn't goodenough);andmetal film (low noise)resistors.
Metalfilm resistorsaregreatfor audioprojects,but they
caDcostplenty. Sometimesyou caDpick up metal film
resistorssurplusfor a fraction of the originalcost;which
is worth i³. Otherwise,stick to the commoncarboncom-
positiontype.
Figure1.3
Potentlometers
Potentiometers(or pots, asthey're commonlycalled)
'd.temembersof the resistorfamUy,exceptthat they are
variableresistors.As you CaDseein Figure1-3,apoten-
tiometeris just a circular resistanceelementwith aslid-
ing conductorcalledawipergoingacrossit. A pot serves
the samefunctionin electricalcircuitsthat a faucetdoes
in plumbing,namely,to regulatecurrentf1ow.Themost
commonexampleof apot is thevolumecontrol on your
ampor radio.
1

9. sometimesoneor maTepotentiometerelementsarecom-
bined,producingatwo-or-more-sectiongangedpot. Pots
caDalgo comewith an on-orf switch mountedon the
back.Miniaturepots for set-and-forget-typeapplications
calledtrimpots algoexist. Theseareelectricallyequiva-
lent to regularpots, but arephysicallytiny andnot de-
signedfor continuouœhandling.Theyusuallymountwilli
othercomponentson aprinted circuit board.
Good pots areunfortunately bard to obtain in smalI
quantitiesat law cost.Adequatepots arefairly easyto
find. Some pots aresealedEromthe outsideair; thispre-
ventsdust and pollution Eromcoatingtheresistanceele-
ment and giving scratchynoises,aswell asproducinga
maTereliable device.Most commonpots,however,are
not hermeticallysealedand aresubjectto long-termde-
terioration. Therefore,when you usepots in a project
always make SUTethey are accessibleand removable.
You'll beg³adyou did a rewyearson downthe road.
You'll note that thereareactually iwo variableresis-
tors in apot; asthe resistancebetweenterminalsl and2
getssmallerdueto movingthe slidingconductortoward
terminall, theresistancebetweenterminais2 and3 gets
larger.Movingthe wiper in the oppositedirection pro-
ducesoppositeresults.Sometimesyou needto useboth
resistanceelements,but manytimesyou'll only useone.
If you connectup terminals2 and 3 or l and 2 only,
you havewhat is calledarheostat.However,to simplify
matterswe'nreferto anythingthat's avariableresistance
controlasapot.
Oneother characteristicof pots, taper, might cause
someconfusion.The taper of a pot is anotherword for
the rate at which the resistanceelementchanges.The
mostcommontaper is linear,which meansthat thereis
a linear changein resistancethat occurswhenyou move
the pot - turning it halfway giveshalf the resistance,a
quarterof the war givesaquarterof the resistance,two-
thirds of the war givestwo-thirds the resistance,andso
on. A log taper pot, however,hasits resistanceincrease
logarithmicanyfrom one end to the other. This means
that turning the pot up halfway coversonly about 10%
of thepot'stotal resistance;turningthepot up two-thirds
of the war coversabout40%of the total resistance;and
asyou getpastthis point, eachdegleeof rotation of the
control continuesto coveraprogressivelygreateramount
of resistance.The reasonfor producinga control that
fonowsalogarithmiccharacteristicisbecausethehuman
ear itself respondsto soundsin a logarithmic fashion;
that is, for a soundto appearto steadilyincreasein vol-
ume,you haveto actuanyincreasethe soundin progres-
sivelylargeramounts-or logarithmically,in mathemati-
calterms(seeFigure1-4).Asaresult,in volumecontrols
it is frequentlymaTedesirableto havealogarithmicresis-
tance changeto compensatefor the characteristicsof
humanears.Electricallyspeaking,however,alineartaper
pot (whichiseasierto find) win do thejob just aswenas
alog pot, althoughthe actionmightnot feelasgood.
Figure1-5
Clockwise[rom upperleft-handcorner:adual-sec-
tion gangedpot, a single-sectionrotary pot, a rota-
ry pot with anon-off switchmountedon theback,
aminiaturetrimpot, anda linearslidepot.
Figure14
A volumechangelike this (a) soundslike this (h)
toyour ear.
Capacitors
Thereare three main characteristicsthat interestus
asfar ascapacitors("caps" for short)areconcerned:the
value(amountof capacitance),theworkingvoltage(how
muchvoltagethe capacitorcanwithstand),andthe size.
Capacitorsvary widely in size(unlike resistors,thereis
no "standard" capacitorpackage),and for samesmaller
projectsit's a goodideato makeSUTethat the capacitor
you needcanfit in thebox that you'vegat.
A capacitor'svalueis expressedin larads, with one
complication.A faradis a wholelot of capacitance-far
too much to be usuablein many electronic circuits.
Therefore,capacitorsare usually rated in microfarads
(abbreviated,uF; in older literature, the abbreviations
mld and mi are sometimesused),a microfaradbeing
one-mi³lionth of a farad (0.000001 farads). Thereare
even some very low capacitancecapacitorsthat are
valuedin micromicrofarads(a mi³lionth of a millionth
Potentiometerscomein avarietyof styles(seeFigure
1-5.'Themostcommonisthe singlerotarypot, although
lint'Jf slide pots are gainingin popularity, especiallyin
imported consumerelctronic equipment. Additionally,
12

10. of a farad-pretty tiny!) Severalyearsagothis wasab-
breviatedasW, but nowadaysthe prefix pico usual1y
rep1acesthe prefix micromicro, and pico is certain1y
shorterand easierto dealwith. Apicofarad abbreviates
as pF. Don't be confused-a pF is the sameasa JJIlF,
just amoremodernname.
As in the caseof resistors,schematicsin most other
partsof the wor1ddesignatecapacitorvaluesin adiffer-
ent way from Americanschematics.First of an,in addi-
tion to the .uf and pF, theseschematicsfrequent1yuse
the term nanofarad (abbreviatednF). A nanofaradis
equiva1entto 0.000000001farads.HereareSOfiecom-
moncapacitorva1ues,expressedin.uF, pF, anduF:
0.001.uF = 1,000pF = 1nF
0.01.uF = 10,000pF = 10nF
0.1.uF = 100,000pF = 100nF
it's almost impossible to rut a decimal point in the wrong
place accidentally, as the metric nomenclature strives to
avoid the use of decimal points altogether. Another ad-
vantage of the metric system is that you don't end up
with big numbers-an otherwise clumsy 3900 pF becomes
3n9 in metric, which is much maTeconcise.
Working voltage simply meansthe voltage up to which
a capacitor will wark reliably. If a capacitor is rated, at,
say, 35V and you connect it to a point in the circuit
willi 40V, you will get a warm capacitor or a nonfunc-
tioning one very shortly. Except for highly unusual
cases,you can always use a capacitor willi a working
voltage higher than the one specified. It is not uncom-
mon to have capacitors rated at lODY or maTein a cir-
cuit powered by a 9V battery, simply because one
rated at IOOV may be easierto find or cheaperthan one
rated at 9V. In most any circuit, as long as the capaci-
tors have a higher working voltage than the voltage of
the rower supply feeding the circuit, you're covered.
Size is inconsequential to proper electrical operation,
but in terms of packaging it can get you into trouble.
Capacitor size (as a rough rule of thumb) increaseswith
either higher capacitance or maTe working voltage. If
you're putting a circuit in a smalI box, a IOOOjlFcapac-
itor rated at IOV might fit perfectly, but one rated at
lODY may be bigger than the box itself. For this reason
catalogsfrequently specify capacitor dimensions right
along willi working voltage and capacitance.
There are twa basic types of capacitors we'll be using:
disc types and electrolytics (see Figure 1-6). Disc capaci-
tors alI look pretty much the same-a round, fairly fiat
ceramic blob of variable size willi twa wires coming out
of it. They generally have fairly high working voltages
When a capacit0r value includes a decimal point (i.e.,
1.2 J,tF,4.7 pF, 2.2 nF), the 11,p, or n is inserted where
the decimal p0int would normally appear. Here are sOfie
examples of American nomenclature and the metric
equivalents:
American
1500pF
4.7.uF
O.22.uF
6.8pF
Metric
In5'
4Jl7
220nF
6p8
Wbilethe metric systemof nomenclaturemayappeal
mOlecomplexat first, in actuality it is amOleefficient,
andlessambiguous,wayto designateresistorandcapaci-
tor values.One advantageof the metric systemis that
Figure1-6
radia! mounting electrolytic capacitor
(negativeor minus leadmarked)
dipped mylar capacitor
tantalum capacitor
mylar capacitor
polystyrene capacitor
~ l]~~J2I~,F
papercapacitor
13

11. SemIconductors(ratings of 500Y ale commonon smallervalues),but
limited amounts of capacitance.Most discs can't get
muchmocethan.2.uF packedinto ³bem;abovethat,
they get impossiblybig. Common disccapacitorvalues
ale 0.001, 0.005, 0.01, 0.05, 0.1, and 0.2.uF. Disc
capacitorscan evengive very smalIvalueslike 10 pF.
Theseale about 6.2 mm (1/4") in diameter,whereas
sometimeslike a 0.2.uFdisc can be about 2.5 cm (1")
round.
Unlikethe disctypes,e/ectro/yticcapacitorsale tubu-
lar, and haveeither axia/ or radia/mounting.They algo
haveone other quality: they ale polarized.This means
that electrolytic capacitorshavea plus(+) andminus(-)
end,just like abattery, andlike abattery,iryDu hookup
the plus and minus backwardsit won't wark right. On
most capacitors,only oneleadis markedfor polarity-
importedcapacitorsusuallymarkthe minusend,Ameri-
can ones generally indicate the plus (why, I don't
know). Although resistorsand disc capacitorsaren't
polarized,many other electronicparts ale, andit's im-
portant to hook the endsup correctly.Oneof the moce
commonerrorsencounteredin building electronicstuff
is to miss the polarity of an electrolytic capacitor,a
transistor,or what haveyou; sobecareful.
A lot of capacitancecanbe squeezedinto anelectro-
lytic-they may go up to 40,000.uFor moce.For audio
wark requiring smalIamountsof power,though,you'll
rarelyuseacapacitorlargerthan 1OOO.uF.
Onecharacteristicworth mentioningaboutelectrolyt-
icsisthat they age,becauseinsidethebody is achemical
that can eventuallydcy up. This takesanywhereflam
severalyearsto many decades.Althoughthiswon't bea
problemfor most experimenters,if you expectto usea
pieceof equipmentfor many,manyyears,let the elec-
trolytics beaccessiblefor replacementshouldonedeteri-
orate.
Thereale other typesof capacitorsyou'll encounter.
Papercapacitorsale tubular, and fairly large;they have
the samecapacitancelangeasdiscsandale algOnonpo-
larized.They ale not much in voguethesedaysbecause
they ageandhavebeenreplacedby my/ar types,which
look similar to paper types, have many of the same
characteristics,but last longer. For smalIand slabIeca-
pacitancevalues(in the pF range),you'll encounterpo/y-
styrenetypes.Theseale tubular, verysmalI,andusually
plastic and silvery. The premium capacitorsfor large
capacitancevaluesale tanta/um types; theseale quite
expensiveunlesspurchasedsurplus.They ale very reli-
ableandperformwell in critical circuits.
The final type of capacitorwe'll coveris the variab/e
kind. Theseale seldomusedin audio circuits,because
you can't make variablecapacitorswith lots of capaci-
lance, and audio circuits generallyrequirelargecapaci-
tancevalues.Thevariablecapacitoris to capsasthepot
isto resistors.
In addition to conductors and insulators, there is a
third class of material that exhibits properties of both.
Under SOfieconditions, it acts asan insulator, and under
other conditions it's a conductor. This phenomenon is
called semiconducting-hence the name semiconductor-
and allows a variable control over electron f1ow, forming
the cornerstone of modern electronics. Semiconductors
are calledactive components. Unlike resistors,capacitors,
and other passive components, active components can
(under the right conditions) rut out more than is rut in.
This is called Kain. AlI the projects in this book rely on
SOfie kind of amplifier, which is the term used for a cir-
cuit that givesgain.
You can consider semiconductors the heart of any cir-
cuit; like a human heart, they can work for a long time
if handled properly, but they can algo fail if abused.Ap-
propriate cautions are included in particular projects,
but certain precautions apply to alI semiconductor de-
vices. First, don't overheat them during soldering, as
they can be damaged by excessheat. Anything reason-
able is all right-they aren't as fragile as some people
think-but you do need to take care. Most semiconduc-
tors may be rut into matching sockets, completely elim-
inating the need for soldering. Second,be careful not to
apply either excessvoltage or voltage of the wrong polar-
ity to asemiconductor. Wrong-polarity voltage, for exam-
ple, means connecting the plus end of the battery to the
minus terminal on the circuit rather than the plus (or
positive) one. Although many of the circuits in this book
are protected against improper polarity by two diodes,
the problem still crops up in experimenting.
The simplest kind of semiconductor we'll be using is
called the diode (Figure 1-7). A diode is really basic; it
can't amplify, but its talent is being able to act as an
electronic switch. If the diode points in one way, only
positive voltages can pass through. If it's pointed the
other way, only negative voltagescan get through. If it's
in a circuit which is AC (voltages in both positive and
negative quadrants), one half of the AC will be lopped
orf. The protection circuit for improper polarity I just
mentioned is shown in Figure 1-8.Pointing the diodes as
shown effectively blocks a reverse-polarity voltage from
entering into the circuit.
Diodes come in two basic types: signal diodes and
power diodes. Signal diodes are usually small cylinders,
sort of like resistors, but made out of g³assand sporting
only one band. This band is called the cathode and indi-
cates polarity of the diode the way a (+) and (-) identify
battery polarity.
Power diodes are somewhat larger, although you will
find smalI ones (about the size of a 1/4W resistor) com-
monly available in 1- to 4A ratings. They will workjust
as well in the projects as signal diodes, but signaldiodes
14

12. power diode
rSlthnc³p
can handle a moderate amount of power (certainly mOle
than we need for the various projects), and cost less.
Diodes ale rated according to two characteristics:
voltage-handling and current-handling ability. It's com-
mon practice to use a diode that's considerably over-
rated, because the cost difference isn't that much and
the reliability can be higher.
Figure 1-9 shows several examples of my favorite
kind of diode, which is different flOro all the others; the
light-emitting diode. This relatively recent addition to
the diode family emits light when you feed it a couple of
volt s (howabout that). Right now, the most commonly
available color is red, but you can also get green,yellow,
orange, and two-color types for a somewhat higher plice.
Light-emitting diodes (or LEDs for short) neverbum out,
for alI practical purposes,under normai use;it's estimated
that in 100 years, the only change you would detect
would be a slight loss of brilliance. Additionally, because
LEDs don't have a skinny little filament like a regular
light bulb, they're immune to vibration and shock. How-
ever, they can be destroyed if too much current goes
thr"ugh them. Also, because (like any other diode)
they ale polarized, if hooked up backwards they won't
light.
signal diode
(+)-(+)
when pointed this way, only
(+) voltages can {law through
)-(-
when painted this way, anly
(-) valtages can {law thraugh
(+)..:)
blocks positive voltage Figure1-9
LEDsin severaldifferent casestyles.
-):)
blocks negative voltage
Figure1-8
Reverse-polarityprotection circuit.
LEDsgenerallyhavea flat spot on the caseor dot of
paint to indicatethe cathode;however,this isnot always
consistentflOromanufacturerto manufacturer.Tocheck
polarity, I generallyusealittle tester,asshowin Figure
l-ID, comprisinga 9V batteryand resistor.Hook up the
LED; if it lights, the terminal connectingto thebattery
(+) is the anode,and the wire connectingto the resistor
is the cathode.If it doesn'tlight, switch the LED leads
around. If switchingaround the leadsdoesn't produce
somelight, you haveeitheradeadbatteryor adeadLED.
A mOlecomplexsemiconductordeviceis the transis-
tor. A transistorhasthreeterminais:oneis the collector,
one the base,and onetheemitter. Electronsaleemitted
via one terminal and collected on another terminal.
while the third terminal actsasacontrol element.Tran-
sistorscomein avarietyof casetypes,flOrosmalI,epoxy-
plastic types (see Figure 1-11) to large, metal-cased
models(powertransistors).
~(+)
if battery is hooked up
correctly, diodeslet
. the voltagethrough
.
volt
meter
15

13. Figure 1-10
LED tester.
as they ale a hassIeto work with, ale mole expensive
(exceptin surplus),andale usedmostly by peoplelike
NASA where the thingshaveto work on the dark side
of the moon. For those of us stillon earth, however,
DIPswill do just fine (refer to Figure 1-12for illustra-
tionsofthe different packages).
Figure1-12
The leftmost IC is mounted in an 8-pin minidip
package,the center IC in a TO-5round package,
and the rightmostIC in a 14-pindippackage.
Figure 1-11
11zetransistoron the lelt is in a metal case;the
oneon theright isin anepoxy-plasticcase.
~
i
Ii
Wewon't beusingmanytransistors,however,because
technology bas made the singletransistor obsoletein
many applications.Instead,a bunch of transistors,di-
odes,and other materialsthat mimic the f~nctions of
resistorsandcapacitorsaredepositedon asinglecrystal.
line basecalleda substrateto perform a completefunc-
tion, suchasamplify. Thesesophisticatedsemiconductor
devicesare calledintegratedcircuits (ICs). You canfind
almostany electronicfunction in an IC, from computer
memory cells to a duallow-noiseaudiopreamplifierto
tone generators-evenmedium-powerhi.fi amplifiers,
electronicgaincontrols,octavedividers. . . all kindsof
things. ICs are commonly packagedin three types of
cases:llatpack, DIP (dual in-line package),and,for lack
of a better term, round.I advisepassingup llatpack ICs,
Other IC packagesale in use, but we will only be using
either DIP or round types in the projects.
There ale twa major families of ICs, linear and digi-
tal. Digital ICs ale used in computers, calculators, digital
clocks, and other decision-making or number-counting
circuits. The tuning standard (Project No. 16), which is a
variation on a counting circuit, usesdigital ICs; so does
the electronic footswitch (project No. 15), which basto
make decisions (should I switch the effect in or out?)
However, most of the projects feature linear ICs.
Linear ICs amplify, oscillate, ftlter, and do other interest-
ing things. AlI audio equipment is based on linear cir-
cuitry, and the audio modifiers in this book ale no ex-
ception.
By far the most popular linear IC is the operational
amplifier, popularly calIed an op amp. This is simply a
high-quality amplifier, capable of large amounts of gain,
predictable behavior, law noise, and good frequency re-
sponse. Since it's very difficult to get alI desirable char-
acteristics packed into one op amp, there ale many dif-
ferent op amps to choose flam. Same specialize in law
noise at the expense of other characteristics, same haye
really good frequency response but lots of noise, same
ale designed solely to be blow-out proof, same ale de-
signed for low-budget applications, and so on. We'lI
mostly be using either low-noise- or extended-frequency-
responseunits.
Same people get confused over the numbering sys-
tem for ICs. ICs typically have 8 to 28 terminal s, each of
which is assigneda number for identification purposes.
The numbers ale assignedin the folIowing m-anner:look-
ing at the IC, you will seesame kind of notch, dat, or
other identifying maIk at one end of the IC. With this
notch pointing up, as in Figure 1-13, the pin in the ex-
16

14. trefie upperleft-handcomersis pin I. Thepin belowit
is pin 2; continue counting until you reachthe end of
the row. At this point, jump overto the bottom of the
next row andcontinuecounting,but this time count up.
The highestnumberpin is thereforein the upperright-
bandcomer.
RoundICshavesomekind of tab,which indicatesthe
highest-numberedpin. Looking at the IC from the bot-
tom (or, the sidewherethe leadscomeout), the pin to
the immediateright of the tab is pin l. Continuecount-
ing clockwiseuntil you reachthe tab,which isthehigh-
est-numberedpin.
Peopleoften becomeconfusedoverIC nomenclature
aswell asthe pin numberingscheme.Whena company
inventsan IC, it assignsthat part acertainnumber-say,
741-and then addsa prefix that standsfor thenameof
the company.Whenother companiesproducethe same
part, they in tum add their own prefix to the number;
Figure 1-13
Identifying IC pins.
notch
dat
"
for example,an LM741 is madeby NationalSemicon-
ductor, an MC741by Motorola, a jlA741 by FairchiId,
an RC741by Raytheon,andsoon, An additionalsuffix
may be addedto indicatethe type of packagingusedfor
the IC, so that a 741 in a plasticcasewould bea 741P,
andthe samepart in aceramiccasewouldbea741C.
Finally, the prefix or suffix maybemodifiedto indi-
ca³ecertain additionalaspectsof the IC's performance.
An RC4739is a Raytheonpart designedfor commercial
use;anRM4739is a Raytheonpart designedfor military
use. Military parts are generallycapableof operating
over a wider temperaturerange,andmeetcertainhigh-
reliability requirements set up by the government.
However, they are considerablymore expensivethan
consumergradeparts,and arenot cost-effectivefor aur
applications.
By the way,manysemiconductorvendorsdo not buy
parts from just one manufacturer,sinceseveralmanu-
facturersoften makeidentical parts.Sa,ratherthan in-
dicate that they havean RC741or an LM741 in stock,
they'll just saythey havea 741 anddropthe prefix and
suffix. In this case,you can assumeyou're buying a
plastic-packageddeviceintended for consumerapplica-
tions.
A coupleof peoplehaveaskedme why other parts
arenecessaryif ICsarea completefunctional unit. The
answeris twofold: certainpartsaredifficult to fabricate
on an IC; and ICsareusuallysetup asgeneral-purpose
devices.Otherpartsdo thingslike determinethe amount
of gain,currentdrain,andfrequencyresponse.
Wire
'manufacturer
(in this case,
it's National
Semiconductor)
IC identitication
number
You'd think the subject of WiTe(see Figure 1-14)
wou1dbe simp1e-it is, but willi same complications.
The simplestkind of wiTeis barewire-a solid, fairly
thick pieceof carrer (or maTelikely thesedays,cop-
per alloy), which can take electronsfrom oneplaceto
another. This kind of wiTeis popularly referredto as
buss(or hus) wire.
The next step up in complexity is insulatedwire-
wiTecoveredwith a plastic sleevingor insulatorwhich
keepsit from shorting out to any other wires.Next is
stranded wire-many thin bare wires coveredwith a
plastic sleevingthat insulatesthe entire bunchof wires
and holds them together. StrandedwiTehasthe advan-
tageof being sturdier if the wiTegetspushedarounda
lot; if you pushsolidwiTearoundtoo much,it canbend
andbreak.
Thesethreetypesofwire arewhatyou'll usefor most
point-to-point wiring in the projects.Onehandyfeature
of insulatedwiTeis that the insulation comesin dif-
ferentcolorsto facilitatecolor-coding.
4
round package type
(bottom view)
7
014
013
.,- P 12
~ 011
010
09
1 .
dip package type
(top view) 2 I
3
3 I.J-J
00
O
4 .
S

15. Gaugeis the propertenn for wiTediameter;the best
range for wiTe in these circuits is from #22 (largest prac-
tical) to #28 (smallest practical). The larger the gauge
number. the thinner the wiTe.
Figure 1-14
Wire types.
:=::=:::::~
'" =
bale wire
~v
:::::::
r ::::::::::::::::::,
bare wire with insulation (or solid-cole wire)
:::::::
strandedwire
~
~
Low-capacitanceshieldedcableis a type of shielded
cabledesignedspecificallyfor audioapplications.With-
out gettingtoo technical,sufficeit to sarthat allshielded
cable exhibits a certain arnount of capacitance.Under
someconditions this capacitancereducesthe treble re-
sponseof an instrumentsuchasguitar, especiallyif the
cableis longer than a rew meters(yards).For OUTpro-
jects, it certainly doesn't hurt to uselow-capacitance
cable,but it's not reallynecessary;regularshieldedcable
will do the job just finf, sincemost of the cablelengths
will beunder 15cm(6") or so.
Thlistedpair is similar to shieldedcable;by usinga
pair of wires, twisting them, and connectingone to
ground,the other oneis somewhatshielded.Thoughnot
aseffectiveasthewrappedtype, it's still usefulfor maur
applications.A type of wicewe won't beusing,but you
sef a lot, is magnetwire. This is extremelythin copper
wice,coveredwith a lacquertypeof insulation,whichis
usedfor windingcoilssuchasguitarpickupsandspeaker
coils.
Coi! cableI usuallymistrust,unlessit wasmadefor
Bell Telephone.The inexpensiveimported coil cords
commonly sefUarf shielded,but the shieldis a flimsy
kind of cloth with copper depositedon it in all the
sampiesI've lookedat.
Thelasttype ofwire weneedto checkoutiszip cord.
This is the brownish kind of wice found usually on
toasters,larnps,radios,and other applicancesthat plug
into the wall. Zip cord is two heavilyinsulatedconduc-
tors designedto carry a reasonableamountof current.
It's useful for speakerwires and power supply wires.
One fact many peopledon't know: the two different
conductorsof zip cord arf coded.Usually,one sideof
the conductor'sinsulationis ridged,while theinsulation
on the other sideis smooth.Whilethereisno real"stan-
dard" on the subject, most people using zip cord as
speakerwice usethe ridgedconductorfor the hot lead
andthe smoothconductorfor thegroundlead.
..,/~
two-conductor cable
zip cord
shielded cable ;>;'
Mechanical Parts
The next part of the wire world worth looking into is
Gable,which we'llloosely define as more than one insu-
lated wire inside a plastic sheath. Most musicians are
familiar with shielded Gable,the kind of wire usedin gui-
tar cords. Shielded cable bas one (and sometimes more)
insulated conductor, wrapped or covered by same form
of conductive' shield. This shield is usually same kind
of conductive foil or crisscrossing pattern of very fine
wires. By connecting the shield to a ground point, the
wires which it wraps around are lesssusceptible to stray
hum or radio signals.The wire inside the shield is referred
to as hot compared to the shield, which is grounded (no
volts-remember?). Sometimes shielding is not required,
in which casethe cable is simply referred to asmultiple-
conductor cable.
Knobs. Everybody knows what a knob isoWhat you
may not know is that there are different methods to hold
knobs onto pot and switch shafts. Cheap knobs simply
rut grooves on the inside plastic wall which mate with
matching grooves on the pot shaft. Types willi a set-
screw in the back are somewhat better, but the best are
the kind with iwo setscrews,placed ninety degreesapaTio
This dual retaining action holds the knob on its shaft
tightly and securely. Sometimes the setscrewsuse stan-
dard screwdriver slots, and sometimes hex nuts. To take
orf a knob willi hex nuts requires a iDol called an Allen
wrench. Chances are, though, that you won't run into
these too often, ashex nuts generally are indicative of a
high-priced knob.
8

16. Switches.Switchesgenerallycompleteor interrupt a
circuit. Figure 1-15 shows a simpleloggieswitch sche-
matically.With the switch closed,a conductorconnects
wiresA and B; willi the switch open,A andB aleeffec-
tively insulatedfrom eachother. Most on-orf switches
ale of this type. Theyale calledsingle-pole,single-throw
switches(or SPST)becauseone wiTe,the pole, canbe
switched to one other wiTe(the throw). A single-pole,
double-throw type (SPDT) can switch a wiTe to two
other wires (Figure 1-16).A double-pole,double-throw
switch, (Figure 1-17) can switch eachof two wires to
two other wires. A toggle switchbaseachof the poles
and throws brought out to a solderterminal,usuallyin
a logical way, and comesin regularor miniature sizes.
Figure1-17
DPDTswitch (schematicized):as2 connectsto l,
B connectsto A; when2 connectsto 3,B connects
loCo
1
r3
A Lc
Figure 1-15
SPSTswitch.
Figure 1-18 showswhich terminalsconnecttogether
whenyou pushthe switch togg³ein different directions
for a miniature togg³eswitch.Notethat pushingthe tog-
g³eup connectsthemiddle andlaweTterminalstogether,
while pushingthe toggledown connectsthe middleand
upper terminals together. Also, note that any DPDT
switch can be usedasan SPDT,DPST,or SPSTswitch
by simplynot usingalI the availableterminals.
conductor
wire A --J o wireB
closedSPSTswitch
wire A <f"~ O wire B
open SPSTswitch
Figure1-18
The temzinaisconnecting together for the two
loggie positions o[ a typicai miniature SPDT
switch.
Figure1-16
SPDT switch: wire C can connectto eitherwireA
or wireB.
wiTe A O
Figure 1-19 showsa number of switches.The slide
switch is lessexpensive(but also somewhatflimsier)
than toggletypes.I tend to avoidthem becausethey're
hard to mount, and their non-airtight construction
tendsto pick up dustanddirt.
Pushbutton switchesperform a switching function
whenyou pushdown on a button. Sometimestheseare
avaiiablein a sturdy case(asshownin thephoto) that's
suitablefor footswitching.Unlike ordinarypushbuttons,
19

17. Figure1-19
Dipswitches ale not really intended as front panel
switches;they have the samerelationshipto regular
switchesastrimpotshaveto regularpotentiometers.
It's sometimesimportant to know the currentrating
of the switch, as well as the switchingconfiguration.
Most togg³eswitchescan safelyhandle2 or 3A of cur-
rent at 12SV,which meansthat they cancontrol a fair
amount of juice (about 2S.0W).For us, aDYswitch can
handlethe voltageswe'll be dealingwith; however,dip-
switchesale not ever suitablefor switching IISV AC.
Figure 1-20
Single-pole,five-throw (SP5T) rotary switch.
footswitchesdo not haveamomentaryaction,but asus-
tainedaction.This meansthat pushingthe button ODce
tlips the switch oneway, andpushingit againtlips the
switch the other way. There'smore material on foot-
switchesin Project No. 11, and Project No. 15 shows
youhow to replacethe comparativelyrareandexpensive
DPDT footswitch willi a more common (availablein
hardwarestores,for example),lessexpensiveSPSTtype.
More complicatedswitchingrequiresarotary switch.
This bas phenolic or ceramic wafers with terminals
broughtout for the polesandthrows.Usuallythemech-
anismworks similarlyto the onedetailedin Figure1-20,
with a detentmechanismhookedup sothat the rotary
switch clicksasyou tum it aroundandthe variouscon-
ductors line up. Single-pole,6-throw (SP6T), double-
pole, 12-throw(2P12T),andotherexoticswitchingcom-
binationsarepossible.
Willi rotary switchesand SOfieother switch types,
which terminalsconnecttogetherin variousswitchposi-
tions may not be entirely obvious.To fmd out, usea
continuity testeror ohmmeter(seeProject No. 19) to
check for continuity (a completed circuit, in other
words) betweenthe various switch terminals; make a
note of which terminals connecttogether in various
switchpositions.
Dur fina³ switchtypeis thedipswitch.Theonein the
photo containssevenminiatureon-orfswitchesin a case
not muchbiggerthan a conventional14-pinIC; in fact,
dipswitchesaresize-compatiblewith standardICsockets.
20

18. Figure 1-21
Four commonly used batteries. The little one in
the front is an "AA" celi; the large one on the left
is a "D" celi; the one standing up in the middle is a
"C" celi; and the one on the righ t is a 9 V transistor
radio battery, suitable for use in mony of our pro-
jects.
Batteñes. Batteñes come in different sizes,voltages,
and current-producing capacitieso Figure 1-21 shows
faul available types. The transistor radio battery is the
kind most often used in accessoriesfor the electronic
musician; it combines smalI size willi a fair number of
volts, and a moderate amount of current-generating
capability. "AA" cells, commonly called "penlite" cells,
produce the least amount of ampere-hours (amount of
current for a given amount of time). "D" celIs ale the
most powerfulo However, combining severalbatteries to-
gether in series (Figure 1-22) increasesthe current-gen-
erating capacity, as well as increasing the available vol-
tageoGiven that one "AA" battery will produce loSY,
then twa batteries will give 3Y, six will give9Y and soono
Figure 1-22
Combiningthree 1.5V batteriesin seriesto yield
4.5Y:
~~~==:=:~=}+----~.,~
Batteries are algo made from different chemical com-
pounds, which give different rower capacities.The sim-
plest and shortest-lived type is the carbon-zinc battery.
Alkaline cells give a longer life, although for circuits
willi low current drain there is lit tle (if any) economic
advantageto using them; alkaline batteries are most use-
ful in circuits requiring a fair amount of juice. Another
kind of battery is the mercury battery, although 1
wouldn't recommend it for most musical uses.It main-
tains a fairly constant output voltage until the end of its
relatively long life, at which point the output voltage
drops rapidly. For this feature, you have to par a whole
lot, and it just doesn't seem to be worth it (especially
considering the ecological aspectsof throwaway mercury
batteries).
You will notice that there ale devices on the market
which claim to recharge carbon-zinc batteries. Actually,
a lot of controversy surrounds chargingbatteries-does it
really work and isit dangerous?The answerto both ques-
tions is yes. You caDrecharge carbon-zinc batteries (as
long as they aren't too far gone) to close-to-new condi-
tion; however, if left to charge for an extended time,
they caD explode, sending battery acid out in various
random directions. For this reason, most professional
electronics people frown on rechargingbatteries.lfyou're
liable to forget about charging a battery for a couple of
days, 1suggestnot doing it.
Nickel-cadmium batteries, as opposed to carbon-zinc
ones, ale designed to be rechargeable. They require a
special charging unit, which rechargesthem safely at a
fixed, slow rate. It is possible to get nickel-cadmium-
type "AA," "C," and "D" cells, but rechargeablenickel-
cadmium transistor radio batteries ale still quite fale.
For batteries, you've got to have battery holders.
Electronics stores carry plastic or aluminum holders for
"AA," "C," and "D" cells; some caDhol d up to six or
even ten batteries of a kind. When holders ale for mole
than one battery, they ale alwayshooked up in seriesto
increase the voltage. A useful hint to know (since 9V
battery holders ale difficult to find) is that a 9V battery
wil fit in a "C" cell holder.
Nine-volt batteries have a special connector which
you've probably seen inside commercial modifiers or
transistor radios. These snaponto the end of the battery
and have two leads coming out, one black and one red.
The black lead stands for minus (-) and the red for plus
(+); mOle on them in Chapter 4.
A piece of slightly esoteric knowledge: by placing
your tongue across the two terminals of a 9V battery,
you can determine its freshness.A good 9V battery will
give you a healthy, salty-tasting bite. The sharper the
bite, the better the battery. With alittle experience, you
caDtastejust how good a battery iso
Something else to consider is that batteries age;this
characteristic is called shelf life, meaning that should a
battery have a shelf life of two years, evenwithout useit
will be dead artel that time period. Therefore, avoid
buying batteries at places that don't do a brisk trade in
them. Many batteries ale date-coded, so if you can fig-
Ule out the code, bur asnewabattery aspossible.
Finally, remember that batteries just don't work if
they're cold. If you bring in a battery from a vehicle
parked outside in the cold, you'll have to wait until
the battery warms up before it will give proper perform-
ance.

19. Solder Lugs. Solder lugs (shown in Figure 1-25)
mount to a metal chassiswith a screwthroughoneend;
the other hole is for attachingwiresandmakingsolder
connections.Other types fit around the bushingsof
potentiometers,and havesomethingto solderwiresto
at the other end (Figure 1-26).Actually, you caDcalI
anything that is metal and designedto havewires sol-
deredto it asolderlug;for example,apotentiometerbas
three terminaiswhich canbe thought of assolderlugs.
Grommets.Grommets(like the onesin Figure 1-23)
arelittle rubberor plasticdoughnuts.Theyareinstalled
in pass-throughholes for wires in metal paneIs,princi-
pally to keepthe wire's insulationfrom scrapingagainst
the sharp metal that often surroundsa dri11edhole.
You'll seethat most AC line cordspassthrough grom-
metson their war to the electronicinnardsof whatever
they'repowering.
Figure1-23
Figure1-25
Figure 1-26
This photo shows three standard lockwashers for
potentiometers, as wen as a lockwasher with a sol-
der ³ug attached.
Nuts and Bolts. The mostpopularsizesfor electronic
wark are4.40 and6-32.lt's agood ideato bur nutsand
bolts in assortments,sothat you alwayshavehardware
around.Screwlengthsofinterest will be9.3 mm (3/8"),
6.2 mm (1/4"), and21.8mm (7/8"). The6.32typesare
alittle heavierduty, and good for mounting stuff like
transformersandpaneis.The4-40sizeisgoodfor attach.
ing solder lugs, mounting circuit boards, and holding
downterminalstrips.
Lockwashers.Lockwashersgo betweena nut andthe
surfacebeing screwedthrough (seeFigure 1-24).Lock-
washershold the screwtightly andkeepit flam becom-
ingundoneby vibration or other sinisterforces.
Figure 1-24a and 1-24b
(a) Threedifferent sty/esof /ockwashers,'(b) how
a /ockwashermountsbetweenthenut andchassis.
22

20. The terminaIscoming out of switchescaDalsobe thought
of as solder lugs. On SOfie switches and other parts,
you'II seescrew terminaIs (Figure 1-27). Wrapping a wiTe
around the screw and tightening it down is just not asre-
liable assoldering, so I generaIly either avoid these or re-
movethe screwsand solder anyway.
Figure1-29
Figure 1-27
How to recognizescrewterminaisso thatyou can
avoidthem.
terminals Quarter-InchTelephoneJacks.You'lI find 1/4" tele-
phonejacks(seeFigure1-30)on your guitarandat your
ampinputs. ThesecaDbe either stereoor mono. In the
caseof mono, there ale two soldertabs; stereojacks
have three solder tabs, correspondingto the two hot
terminaIsandground.You caDclassifyjacksasclosedor
open.Au openjack islike the onesjust described-jacks,
plain and simple.A closedjack meansthat somekind of
switching action is involved. A good exampleof this
switchingaction is when you plug an earphonejoto a
transistorradio and the speakergoesoff-you're actual-
ly switchingthe speakeron andorf with thejack.
TenninalStrips.Picturedin Figure 1-28,thesethings
ale basicallya bunch of insulatedsolderlugsto which
you caDconnectwires;one of the terminaIswill havea
screwhold for attachingto ametalchassis.Thislug then
becomesyour chassisgroundconnection.
Figure 1-28
Figure1-30
The jack on the left isa stereo type; theone on the
right is a mono open-circuit type.
Quarter-Inch Telephone Plugs. Commonly called
phoneplugs(not to beconfusedwith RCAphonoplugs,
thekind usedon hi-fi equipment).Like switches,solder-
terminaltypes are preferableto screw-terminaItypes.
The mono plug bas iwo connections,one for hot and
onefor ground-the hot is thetir, andthegroundis the
shield.The stereokind bas iwo hot conductorsand a
ground(seeFigure1-29).Thebody ofthe plugis usual.
Iy made of plastic or metal-the metal oneslagi far
longer,andI defmitely recommend³bem.
Figure 1-31 showsa mono closed-circuitjack both
pictorially and schematically.TerminalA is the ground
or shieldterminal, C is the hot terminal, and B is the
~

21. Figure1-31 mono closed-circuit jack Transformers.Figure 1-32 showsa couple of trans-
formers, one audio transformerand one power trans-
former. Powertransformersconvertthe AC comingout
of your wall to a lower voltage.SinceIISV will often
frr semiconductors,the transformer stepsdown that
IISV to 6, 12, 15, or someother low voltage.Trans-
formers can either be center-tappedor not; a non-
center-tappedmodel can only work in certain power
supply designs,whereasa center-tappedone will work
in any kind of supply.Sincewe only useapowertrans-
former in ProjectNo. 13,we'lI specifythe properkind
to useat that time.
Cases.Most cases(or chassis)ale madeof metal for
two reasons:one,metalis a conductor,sothe casemay
be treatedasabiggroundarea;two, metalis far stronger
than plastic or phenolic,the other popularchoicesfor
cases.Your best bet is to stick to the aluminumtype;
steeleatsthroughdrilI bits like crazy,requiresmOleef-
fort to drill, and basinferior shieldingpropertiescom-
paredto aluminum.
with plug not inserted,terminais
B and C short together
c- /-"I::::::::: B
insertingaplug breaksthe
connection betweenB and C
, ./'":=~ o C
L..'=:; B
switch.Bnormallypressesagainstthehot terminalwhen
no plug is present,but inserting a plug pushesthe hot
terminal awayfrom the switch part. With stereojacks,
either one or both hot terminalscan havea switching
actionbuilt-in.
Wheneveryou use a closed-circuitjack, make suce
you're solderingto the appropriatetabs.Mistakingthe
hot terminal for the switch will probably keepthe de-
vicefrom working properly. Thereis atestto avoidthis
kind of mistake called a continuity test, describedin
ProjectNo. 19.
Figure1-32
The transJormeron the leJt is a miniatureaudio
type, which we usein ProjectNo. 3. Theone on
the right is a power transJormersuitableJor step-
pingdown 117VACto 12VAC.
Readlng Schematlc Dlagrams -
Now you know what kinds of partswe'll beworking
with, what they look like, and what their important
characteristicsare. Before we finish, we should talk
aboutrelatingthesepartsto schematicdiagrams.
Schematicsare nothing more than shorthandwiring
diagrams.Instead of drawinga wire, you draw a line.
Whenconnectionsgo to ground,rather than drawinga
line connectingalI the groundpoints together,you sim-
ply attach a ground symbol to whateverneedsto be
grounded.Eachpart is identified by its owo symbol,ex-
cert for integrated circuits. Figure 1-33showsthe sche-
matic equivalentsfor the parts and wiring connections
we've talked about. You'll notice that there ale some-
times two symbolsgivenfor a part-a preferredand an
alternate. The preferredare what I use,but the alter-
natesarecommontoo, sinceschematicsarenot ali stan-
dardized.
Integrated circuits have nearly as maDYschematic
representationsas there are ICs, but we'll usethe two
popular approachesshown in Figure 1-34. The first
illustration showsthe outline of a 741 IC, looking at it
from the top (that is, the surfacewilli the notch or dot).
This method showsall the pins of the IC, alongwith
their pin numbers.Frequently it is not necessaryto
showall the IC pins,sinceSOfiepins arenot of interest
in maDYapplications,andSOfiearen'tevenconnectedto
anythinginsidethe IC. In fact, if you look through the
projectsand notice unconnectedIC pins, don't worry;
it's standardpracticeto useonly thepinsyou need.One
advantageto showingICsin the "skeletonoutline" form
is that it's easyto visualizethe actualwiring, sincethe
schematicsymbollookslike the IC itself.
24

22. -L
--8.-- push-button switch
t connecting wires
---}
alternative version
~~ nonconnectingwires
I
1~ alternativeversion---'
~
-³~
battery
~
--³ several batteries
~
1- (board)ground
,."".
~ (chassis)ground
~
~
r
-
L--1 transformer
~"--
~--= c(
L~ speakerand
U U headphones
~

23. Figure1-34
(a) Typicalsymbolfor the 741,an integratedcir-
cuit containing an op amp (the little triangle).
Pins2 and 3 are inputs; 4 and 7go to thepower
supply; 1 and 5 are necessaryfor applications
which are not of interest to us cu"ently; pin 8
doesn't connect to anything intemally, and is
consideredan "nc" (no connection). (b) Here's
another way to show a 741 op amp. For ex-
amplesof both styles,seesomeof the project's
schematics.
Any pinsnot indicatedon theschematicmaybeignored.
The pins on digital ICsale numberedjust like thenum-
beringschemefor op ampICsshownin Figure1-34.
Since there is no standardwar to show ICs sche-
matically. both methodsdescribedabovewill beusedto
familiarize you with the variouswarg the electronics
world drawsthem.
.35Figure
(a)
(a)
(similar to top viewot
[C, but not necessarily
to scale)
(b)
(b)
(>
eachop amp =144136
The secondillustration showshow to look at a 741
IC schematically.Sincethe 741is anop amp,weusethe
symbolfor an op ampasshownin Figure1-33,andput
pin numbersnextto theleadscomingout ofthe op amp.
y ou'11notice that the power leads,pins 4 and 7, are
showncoming out of the top and bottom of the op
amp triangle. You'll also note that pins l, 5, and S,
which areof no importanceto liS,arenot shownin this
method.
A lot of the ICsweuse,however,arecomplexdevices
containingmore than one op amp:anexampleof thisis
the 4136 IC, which containsfour opampsinonepackage
willi fourteenpins. In this case,wecanstill drawaskel-
eton outline (Figure l-35a) but it's frequentlylesscum-
bersomefrom adrafting standpointto showa complex
IC in the secondmethod of Figure l-35b. The power
supply connectionlines could come out of any of the
op amps;ar, one supplyline could go into oneop amp,
and the other supply line into a different op' amp, as
shown.The reasonwhy it doesn'tmatterwhichop amp
showsthe power connectionsis becausewilli multiple
op amp devices,the power lines arecommonto all op
amps.ProjectsNo. 10, No. 11, andNo. 17 offer exam-
pIesof how to showcomplexICsschematically.
Digital ICs do not havetheir own symbol,soin the
caseof theseICswhatwe'll do is simplydrawabox that
representsthe IC, and numberthe pll connections(see
the ProjectNo. 16 schematicfor an exampleof this).
26

24. Substltutlng Parts
SubstitutingICs. A rew peoplehavebad difficulty
findingsomeof the op ampsI like to use,particularly
the4739 dualop amp.Actually, therealemanysources
thatcarrythe4739,4136,andother ICsusedin thepro-
jects;thousandsof peoplehavefound theseparts with-
out trouble,sohopefully you won't haveany problems
either.Thereasonwhy I've chosenthesepartsovermoce
general-purposeop amps is becausethey ale low in
noise,virtually impossibleto destroy, andinexpensive.
However,in instanceswhereyou aren'ttoo picky about
noise,general-purposeop ampssuchasthe4558dualop
arnp(a very common IC) can substitute for the 4739.
Referto Figure 1-36, which showsthe pinout of the
4558and4739, and follow the directionsbelowto sub-
stituteoneop ampfor the other.
Figure1-36
5558
WiTethe connectionsthat norrnallygoto pin 13of
the4739to pin 7 of the4558.
WiTethe connectionsthat norrnally go to pin 14 of
the4739to pin Sof the4558.
As you caDsee,whatwe'vedoneis comparedthe pin-
outs of the two parts,and whensomethinggoesto, sar
the (-) input ofop ampA ofthe 4739,weinsteadwiTeit
to the (-) input of op ampA of the 4558. . . andcarry
this procedurethrough until all pins (inputs, outputs,
powersupply,etc.) ale accountedfor andconnectedto
the appropriatepins on !he substituteop amp.Remem-
ber that pins 2, 3,4, 10, 11, and 12ofthe 4739do not
connectto anythingintemally.
Severalyearsago,a part calledthe 739 wasmanu-
factured,of which the4739isanimprovedversion.How-
ever,the 739 is not suitablefor usein OUTcircuitsbe-
causeit requiresseveralextra partsnot includedin the
schematicor on the circuit board.Attemptingto usethis
part will produceunsatisfactoryresults.
To substitutefor !he 4136, you can useeither two
555Ssor four 741s.The procedurefor substitutingfor
the 4136 is the same-Iook at !he pinout, identify the
terrninals,and make !he appropriatewiring changesto
accommodatethe different pinout of the substituteIC.
ampA output ll.
ampA (-) input[:
ampA (+) input~
negative supplyl!-
Al positive supply
ZJampB output
~ ampB (-) input
51 ampB (+) input
4739
Substituting resistors and capacitors. Although these
circuits work best with the parts values indicated, those
experienced in electronics will no doubt be able to make
changesto use their parts on band without affecting the
performance of the unit. It's often suitable to use parts
that ale close in value to the ones required. For exam-
ple, if you want a 1.2,uF capacitor and you only have a
1.0,uF type, don't WOlTYabout the difference. Remem-
ber that capacitors ale generally not that precisein value;
so a 1.0,uF capacitor could actually have a true value
that's any where Erom 0.8,uF to 1.2,uFand still be with-
in t 20% tolerance. Likewise, if you need a 100k resistor
and can only get 90k or I10k, don't WOlTYabout i³;
there will be little, if any, difference in overall perform-
ance. Frequently the most important property of resis-
tors is how well they ale matched, not whether they
have precise values. So if two resistors of the samevalue
ale specified, don't change one without changing the
other.
However, do keep in mind that the circuits in this
book have been extensively tested over a period of years
and ale specifically optimized to work with the parts
indicated. Unlessyou ale awale of the consequencesof
what you ale doing, tfY to usethe specified parts when-
ever possible.
WiTethe connectionsthat norma11ygoto pin l of the
4739to pin 1 of the4458.
WiTethe connectionsthat normallygoto pin 5 of the
4739to pin 3 of the4558.
WiTethe connectionsthat norma11ygoto pin 6 of the
4739to pin 2 of the4558.
WiTethe connectionsthat norma11ygoto pin 7 of the
4739to pin 4 of the4558.
WiTethe connectionsthat norma11ygoto pin 8 of the
4739to pin 6 of the 4558.
WiTethe connectionsthat normallygoto pin 9 of the
4739to pin 5of the4558.
27

25. TABLE OF ELECTRONICMEASUREMENTS
Foryour convenience,ibis tablesummarizeselectronic
UT:~t~of measurementandtheir abbreviations.
Ampere(A) - unit of currentmeasurement
MicroAmpere(,l!A) = .000001A
Mi11iAmpere(mA) = .001A
Farad(F) - unit of capacitancemeasurement
MicroFarad(}LF) = .00000l F
NanoFarad(nF) = .000000001 For .001 .tlF
PicoFarad(PF) = .000000000001For
.000001,uf or .001nF
Hertz(Hz) - unit of frequencymeasurement
KiloHertz (kHz) = 1,000Hz
MegaHertz(MHz) = 1,000,000Hz
Ohm(il) - unit of resistanceorimpedancemeasurement
KilOhm (kil) = 1,000il
MegOhm(Mil) = 1,000,000il
(Inactualpractice,the Greekletter Omega(n) iso/ten
imitted. Thus,1OOknbecomes100k.)
Volt (V) - unit of voltagemeasurement
MicroVolt (pA) = .000001 V
MilliVolt (mV) = .001V
Watt(W)- unit of powermeasurement
MicroWatt (,uW) = .000001 W
MilliWatt (mW) = .001W
KiloWatt (kW) = 1,000W
?R

26. A surveyot how andwhereto findparts
at reasonableprices.
Oneof the biggeststumbling blocks for electronic
and electronichobbyistsis finding the parts
to build aproject.However,thisneednot bea
task;in fact, all the partsin this book areavail-
..of sources.You canobtainpartsby
, or from retail electronicsdealers(I generallyusea
my partsneeds).
~ - -~: Parts Sources
Go down to your library or newsstand and check out
magazinespublished expressly for electron-
~ Radio-Electronics, 73,
ScienceElectronics are the most commonly avail-
Look in the back section of these magazines,and
seenumerous ads for mail-order hobbyist supply
These ads generally include a partial listing of
and pñces, as well as giving instructions on how
a catalogue.Many'times this just involves circl-
a number on a leader service card bound into the
; a rew weeks later, the catalogue will arrive at
door. In most cases, mail-order companies have
prices and a wideT selection of parts than local
they sell consumerequipment,suchasstereos,calcula-
tors, and burg³ar alarms,as well asparts. Although a
rew storeshavetheir own sourcesof supply for com-
ponents,most dealersdistribute "hobbyist" partslines
offered by various component manufacturers.While
therearequite arewpartslines,probablythe mostcom-
prehensivecarried by local storesis the Calectroline,
manufacturedby GC Electronics,which includesresis-
tors, potentiometers, semiconductors, transformers,
speakers,knobs, and a bunch of other things, like
preassembledmodules.It alsobasprinted circuit board
kits, cases(both metal andplastic),andbatteryholders.
Many storeswill carry mOlethan oneline, socheckout
what'savailable.
A variation on the independentlocal retailer is the
chainstore.Probablythemostfamiliarof theseis Radio
Shack,with storesall overthe U.S.A.andotherpartsof
the world. Radio Shack carriesits own line of parts,
which is roughly comparableto the Calectroline except
that there is mOleemphasison semiconductors.In re-
cent yearsRadioShackbasstarted stockingSOfieparts
that ale very usefulto electronicmusicians-maybebe-
causeof all the peoplewho havethis book and have
stoppedinto their local RadioShackto look for parts.
In addition to Radio Shack,there ale chainsof a
mOleregionalnature,suchasLafayetteElectronicsand
OlsonElectronics.Again,the Yellow Pageswilllet you
know what'saround.
Onepoint to rememberaboutretail storesis that you
can usually ask questionsabout parts and electronics
without getting funny looks. Frequentlythe personon
the other sideof the counter, and sometimeseventhe
manager,will know lessabout electronicsthan you will
artel you've read this book, but they may be able to
tum you on to eithersomebodyin the storewho knows
what he's talking about, or to a regularcustomerwho
knowsaboutelectronicmatters.
this case, your best tool is the Yellow Pages sec-
phone directory. The subject headings you
. are "Electronic Equipment and Supplies- Dealers"
"Electronic Equipment and Supplies-Wholesale."
are the retail stores, and they want your
or smalI. The prices are gen-
close to list prices because the volume they do is
in comparison with wholesale firms. Frequent1y
29

27. in styling,defects,businessfailure, andsoon). Sothere
is a defmite "let the bUreTbeware"implied in dealing
with surplus storesoThis is not necessarilybecauseof
anydishonesty;rather,thesestoresdon't havetime to go
through all their parts,andthey leaveit up to the cus-
tomer to determinewhether or not the part is suited
for the intended application.Most of the time, surplus
storeswill cheerfullytake backany part you fmd to be
improper, but others don't, andyou can't really blame
themoPeoplefrequently will get an exotic part, blow it
up thrbughlack of knowledge,andblamethe stoleo
Now that all these wamingsale out of the way,
let's examine the benefits of surplus outletsoFirst of
all, the plice is right, but most important, the partsare
frequently difficult to obtain elsewhereandale of good
qualityo A part which may be obsoletefor the space
programmay be perfect for the experimentêr,andthe
savingis substantial.Also, companies will sometimesgo
out of businessand sell their inventory for peanutsto
surplusdealersto minimizetheir losses.This savinggets
passedon to rOll. Additionally, the peopleat surplus
storesalefar mole likely to knowaboutelectronicsthan
the peopleat retaiI stores,sincetheir verylivelihoodde-
pendson beingableto examineabatchof partsandde-
termine whether it's somethingon which peoplewould
wantto spendmoney.
An emergencypartssource,althoughlimitedin scope,
is your local TV repair shop (again,the Yellow Pages
ale a greathelp). Becausethey alenot in businessto sell
parts,they don't havemany onhandfor experimenters,
andif you do requestsomething,it will sellfor list pliceo
This is only fair, becausethey haveto make a living
somehowand can't afford to depletetheir partsstock
unIessthey makesomethingfrom i³. But therehavebeen
many timeswhen I neededa rew feet of solder,or are-
sistor,anda TV repairplacehashaditoSoalthoughit's a
last resort, it's still worth checkingout, andyou might
meet someinteresting and knowledgeablepeoplethat
war (you mayaIsomeetagrouchor two).
Getting the Most out ot Mail Order -
Very rew townshaveenoughelectronicsexperiment-
ersto supporta largeelectronicsretail store;you'II tend
to find theseonly in largermetropolitanareas,andeven
then they may not be ableto offer a wide selectionof
parts.As a result,manyhobbyistshavecometo rely on
mail-ordershoppingasan alternativeto buying through
retail outlets-particularly for locatingICs,whichcanbe
very difficult to find locally, even from distributors.
Mail-ordercompaniesdo not dependon walk-intrade,so
anyonewho livesneara mailbox is a prospectiveclient.
Peoplegenerallyhave two reservationsabout mail-
order houses.The first is that you haveto wait for the
order to be processedand sentbackto rOll, which can
Wholesale stores are a different matter. They are set
up to serve the industrial and/oc TV repair market, and
are used to catering to professionals. They don't like to
be bothered willi somebody who walks in andjust wants
one capacitor, although there are exceptions. If you can
go joto a wholesale place and specify exactly what you
want and act like you know what you're doing, they11
be moce inclined to deal with rOll. Remember, though,
that these places are set up for the professional and that
the employees have neither the time nor the inclination
to do any thinking for rOll. If you're lucky, there will be
a wholesale outlet in your community that also bas an
over-the-counter section for nonindustrial users. Here,
the counter people are moce likely to know about
electronics, and if you are polite and look greenenough,
nine times out of ten they'll tfY to help you willi aDY
questions.
One war to be welcomed at wholesale stores is to
obtain a resalenumber. Wholesalersinterpret resalenum-
bers as an indication of a sincere and professional inter-
est in electronics, and somewholesale outlets won't even
let you through the door unlessyou've got one. The state
you live in issuesresalenumbers, which alIows the profes-
sional manufacturer or distributor to avoid paying sales
tax on the parts he burs, sincethe parts will be resold as
part of a finished product and salestax will be colIected
on that. If you intend to make anything for sale, a re-
salenumber is a valid permit to obtain. However, certain
lega³ obligations mus! be complied with. First, some
stateswill require a deposit; for smalI businesses,though,
this deposit is nominal. Next, if you selI something to
somebody you mus! colIect the prevailing sales tax, and
you are obligated to send to your state the sales taxes
you 've colIected on a regular basis. FinalIy, if you bur
parts for your owo use and not for resale,you mus! de-
clare them as taxable and par the sales tax. Further in-
formation on resale numbers is obtainable from your
county government (see YelIow Pagesunder "Govern-
ment Offices-Sales Tax").
Another branch of the wholesale tree is the electron-
ics distributor. These exist mostly to servethe industrial
market; they expect orders that require hundreds or
even thousands of parts, and carry products from specif-
ic companies. If you're lucky, there will be one in your
area that bas an over-the-counter section. Unfortunately
this practicc is on the decline, as over-the-counter vol-
ume is smalI compared to industrial volume and not
worth the effort to the distributor.
Surplus electronics stores also deserve a look. Some
surplus stores selI a wide selection of realIy high-quality
parts at extremely good prices; others selI trash and re-
jects without giving you any real cash advantage. Re-
member that the reason why something is in a surplus
store in the first place is because the original buyer
didn't want it, due to aDY number of reasons (change
30

28. tfY your patience when you're hot to get started on a
project. Second, there have been many casesof mail.
order fraud (few involving electronics suppliers, how-
ever), and people ale suspicious about sending orf large
amounts of money to some post orfice bOK halfway
acrossthe country. Luckily, though, these reservations
ale not really justified. Sometimes it does take time to
get a part, but I have dealt with dozens of mail-order
suppliersand the averageturnaround time bas been uno
der a week. Many of these companies have toll.free or
24-hour answeringservicesto take credit card or COD OT.
ders,and this can speedup the turnaround time to two or
three days-not bad at all. There have been caseswhere
it has taken two weeks to a month to filI a back order,
but that can just as easily happen when dealing with a
retaiI stole if it doesn't have what you want in stock.
As far as fraud goes, I've certainly bad companies
messup an order from time to time, but theseproblems
ale invariably due to human error rather than malevo-
straighten out aDYproblems. If a company has adver-
tised in a magazine for mOle than six months or SD,you
canbe pretty SUTethat it is a realiable operation. If I'm
unsureof some new place, I'n sendin a smalI order for a
couple of parts; how wen they processthe order will ten
me whether or not I want to order from them again.
To get the best results from mail-order companies,
you should fonowa rew procedures. First, put your
name and addresson the order itself-simply including
it on the envelope return address isn't good enough.
Companiesget really frustrated when they have a check,
a list of parts, and no address. Second, keep aDYcorre-
spondenceseparatefrom orders if you want your order
processedas quickly as possible. Third, avoid COD, asit
costsyou mOle money, and will also delay your order.
Fourth, if you have trouble with a company, write them.
Even the best mail-order houses cannot avoid an occa-
sionalgoof; they have no war of knowing there's a prob-
lem unIessyou ten them. Last of all, if you're asking for
advice,technical help, or something beyond a simple re-
questfor plice lists or catalogues,include aself-addressed
stampedenvelope. This encouragesa prompt (and often
friendlier) response.
37~ if you buy 10, or 30~ ifyou buy 100. Resistorscan
cost up to 15~ each at the retail level; but if you buy
100 at a time, the price goes down to 1.5~ each-one-
tenth asmuch. If you buy just 10resistorsat retail prices,
you 've paid for 100 resistors at quantity prices . . . so
you might as welI get the 100, and have 90 "free" resis-
tors left over for use in future projects. You '11note that
certain parts crop up with regularity in the various pro-
jects (like lOk pots, 2jJF capacitors, I N400 I diodes,
RC4739 ICs, and the like); this is daneon purposeso
that you can buy parts in quantity and savesome bucks.
Another way to stock your lab is to scrutinize the ads
in the back of electronics magazines.One company
might maketa great buy on capacitors, and offer £bemat
a laweT price than the competition for a period of a rew
months. Anothe~omp1V1Y might have law prices on
resistors, wbiJe another specializes in ICs. Keep your
eyesopenfor bargains-onceI ordereda "surprise pack-
age" of lOrotary switches that cost me lessthan I switch
norrnally does, and ended up getting 4 useful switches
out of the assortment. You can definitely come out
aheadon this kind of thing.
There is one caveat, though. Many companies offer
semiconductors which are labelIed "untested." Theseare
sold at rock-hallom prices because most of the time
they wark marginally, if at all. Although experimenters
can have run with untested parts, it's best if you steer
clear of anything marked "untested" unIess you know
how to test for functionality.
Table I shows sametypical high and law priceson
electronic components-but remember that component
prices fluctuate radically. When economic conditions are
good, semiconductormakersselI their stuff as fast as
they can make i£, and prices are high. But assoon asany
kind of recessionhits, prices end up being artificially law
becausethere isn't enough customer demand. Of course,
raw material costs, balance-of-trade situations, inflation,
and a number of other factors ultimately influence the
cost of the parts you use. When you buy this book, we
may be in either feast or famine; look upon the prices
given as guides, not maxims.
Parts Klts
As a convenienceto the readersof this book, PAlA
Electronics(seeaddressin TableII) basagreedto stock
complete parts kits for the majority of the book pro-
jects aswell ascircuit boardsfor theseprojects.Each
parts kit includes a legendedcircuit board, resistors,
capacitors,semiconductors,pots, and requiredsockets,
and in somecases,switchesandconnectors.In caseof
difficulty, PAlA maintainsa repairservice.For further
information and current pricing, write or calI (405)
843-9626to requestthe currentcatalog.
Getting the Best Prlces: Stocklng Your Lab
If you're only buying parts for a couple of projects,
then retail stores are certainly the most convenient war
to shop; but the lowest prices usually come from indus-
trial distributors and mail-order houses (especially on
large orders). One of the best ways to keep parts costs
down is through quantity buying. If you caDlocate fel-
low enthusiasts in your area and pool orders, you can
make substantial savings. For example, a single phone
jack might cost 454, but the samepart may go down to
31

29. There are,of course,manyothersourcesfor purchas-
ing individual components.TableII is apartiallisting of
prominent mail-ordersuppliers;while this list doesnot
necessarilyconstitute endorsement,!'ve bad no prob-
lemsorderingfloro any of thesecompaniesin the past.
Whenyou havenothing to do SOfierainy day,write a
batch of letters to the variouscompaniesand request
their catalogues-you'll find out what's availableand
for how much.
.TABLE lo Representative Prices(SU.S.
law price
(quantity price)
high plice
(list)component
.015
.02
.so
2.50
.05
.10
.20
.50-1
.10
.30
.07
.10
.15
1.10
.75
1.20
.30
.40
.00
1/4W,10%resistors,carboncomptype .15
1/4W, 5%resistors,carboncomptype .20
potentiometers(consumergrade) 2.00
potentiometers(professionalgrade) 5.00
disccapacitors(under0.01,uF) .25
disccapacitors(over0.01,uF) .35
electrolytic capacitors(under 100,uF) .50
electrolytic capacitors(over 100,uF) 1.00-2.00
LEDs .35
741 operationalamplifier .75
smalIdiodes .30
powerdiodes .49
knobs .60
switches(toggle,miniature) 2.95
switches(toggle,regular) 1.75
switches(rotary) 2.00
jacks(mono, closedcircuit) .65
jacks(stereo) .75
casesaredifficult to locate;pricesvary from $2to $10typically
32

30. TABLE II. PartialList of Mail-OrderHouses
International ComponentsCorporation-PO Box 1837,
Columbia,MO 65201. Semiconductorsand other com-
ponents.
International. Electronics Unlimited-225 Broadway,
Jackson,CA 95642.Semiconductorsandotherparts.
Jameco Electronics-1355 Shoreway Road, Belmont,
CA 94002.Manysemiconductors,components,kits.
MeshnaElectronics-Box 62, E. Lynn, MA 01904. In-
terestingsurplusequipment,samecomponents,things.
MouserElectronics-11511WoodsideAvenue,Lakeside,
CA 92040. Broad-lineindustrial distributor; mostly im-
ported parts. Pots, resistors, capacitors, connectors.
Fairly largeminimumorderrequired.
Newark Electronics-500 N. Pulaski Rd., Chicago,I£
60624. Broad-lineindustrial distributor; gearedtowards
servicingindustrialaccounts.
OlsonElectronics-260 S.ForgeSt.,Arkron, OH44327.
Generalelectronics,hi-fi, radio stuff, parts, and soon.
PAlA Electronics-l020 W. WilshireBlvd.,Oklahoma
City, OK 73116.PAlA offers a broadline ofmusic-
ally orientedkits, andprovidespartskits andcircuit
boardsfor the projectsin thisbook.
Po³y Paks-Box 942, Lynnfield, MA 01940. Semicon-
ductors, surplus, readouts,hobby stuff, assortments.
QuestElectronics-POBox4430,SantaClara,CA95054.
Semiconductors,components,kits.
Radio Shack-not mail order,b'utcarriesa line of elec-
tronic parts.Variouslocations;checkthe Yellow Pages.
Solid Sta³eSales-Box74, Somerville,MA 02143.Com-
ponents,semiconductors,somesurplus.
Allied Electronics-401 East 8th St., Fort Worth, TX
76102. Broad-1ineindustrial distributor; not necessarily
inexpensive.Partscan usuallybe orderedthrough local
RadioShackstores.Incidentally, Allied s~ocksthe CLM
6000opto-isolatorusedin sameof theseprojects.
Ancrona Corporation-Box 2208, Culver City, CA
90230. Mostly semiconductor oriented; components,
otheritems.
AP Products Inc.-Box 110, Painesville,OH 44077.
Makersof experimenters'breadboards,which are fan-
tasticlittle toys that makeit easyto prototype projects
without soldering.Check it out ifyou like to experiment.
Burstein-Applebee-3199Mercier St., KansasCity, MO
64111. Broad-linedistributor of componentsand elec-
tronic products.
Digital ResearchParts-PO Box 401247, Garland,TX
75040.Carriessameparts,modules,surplus,etc.
Delta Electronics-Box 1,Lynn,MA 01903.Parts,equip-
ment,transformers,interestingsurplusthings.
Digi-Key-Box 667,Thief RiverFalls,MN 56701.Capac-
itors, semiconductors,resistors,diodes,otheritems.
Electronic Distributors, Inc.-4900 N. EIston Ave.,
Chicago,IL 60630.Generalelectronics,parts,tools,test
equipment.
GCElectronics-Rockford, IL 61101. Manufacturersthe
Calectroline of parts; write for info on nearbydealers
carryingthis line.
Integrated Circuits Uitlimited- 7889 Clairemont Mesa,
SanDiego,CA 92111. Semiconductorsand sameparts.
11

31. Before you do any building, you need
tools and a knowledge of how to care
for them. This chapter covers drills,
hacksaws,files,pliers,cutters,strippers,
screwdrivers,solderingequipment,plexi-
glasstools,careof tools,and safety tips.
The partscostof electronicprojectsisn't too high-in
fact, ODceyou learn the ropesof parts buying, you'll
find that you canduplicateequipmentthat sellsfor hun-
dredsof dollarswith one-fifth the cashoutlay. However,
you will haveto bur sometools; this isaninitial invest-
ment which will par for itself if you plan to get into
music and electronics.Luckily, no really expensiveor
hard-to-findtools are necessary.A basichand tool set
caDcostaround $60, which isn't really too muchwhen
spreadovera rewprojects.Besides,someof them(like a
vise)you mayalreadyhavelying around.Let'scheckout
what's most useful, and someprices. Rememberthat
prices givenare approximate,and caDvary widely de-
pendinguponthe vendorandquality.
Thebiggestexpenditureis a gooddrill. I recommend
the kind that caDtake a 3/8" bit. Thoughsl.ightlymoce
expensivethan the 1/4" kind, 3/8" is a commonelec-
tronic dimension, and a 3/8" drilI usually implies a
heavyduty machine.Another neededfeatureis variable
speed.SomevariablespeeddrilIs can evenreversethe
drill bit direction or rotation at the flick of a switch.
This featureisn't realIy necessary,but if you've got the
bucksyou might find it usefulsometime. Do makesuce
that your drilI has a smooth variable speedaction,
though,from minimumto maximumspeed.You canex-
pectto par anywherefrom $25to $45for a drilI.
To go alongwilli your drilI, you'll alsoneeda setof
bits. TypicalIy you caDget a set of averagesmalIbits
(from 1/16" up to 1/4") for around$4.Theywon't last
forever,but if you're only drilIing aluminumandplastic
they'lI drilI a lot of holesbeforethey poop out. If you
don't want a fulI set, you caDget by with three bits:
1/16" (for drilIing pilot holes -see Chapter4); 1/8";
and 9/64" or 5/32". You'lI alsoneedthe 3/8" bit men-
tioned earlier, and uniessyou're content to do a lot of
filing, a 1/2" bit. Unfortunately thesebigbits aresome-
what costly ($5 or so). If you're strappedfor cash,just
get a 3/8" bit and enlarge the hole it makes with a file
or tapered reamer if you need something bigger. Tapered
reamersaren't too expensiveand are useful for deburring
or enlarging previously drined holes (more about debur-
ring shortly). A 1/2" diameter model is preferable to a
1" type.
Your fina³ piece of drining equipment is a center
punch. The purpose of this device is to punch a smalI
dimple (indentation) in metal or plastic by tapping it
with a hammer on the nonpointed side. This dimple
keeps the drin bit centered during its first rew revolu-
tions. You caDget by with a nail in a pinch, but a real
center punch is far more accurate.
y ou'n also need a hacksaw, principally for cutting
potentiometer and rotary switch shafts to length. Al-
most any kind will do, but Us.ea blade with fairly fiDe
cutting teeth. While you're at it, get a spareblade-you'n
need it at SOfieunexpected later moment.
While we're still talking about metal-working equip-
ment, you'n also want a rew files. In addition to the hole-
enlarging ability mentioned previously, when you drin
holes in metal lit tle burrs are left around the perimeter
of the hole; you caDuse a file to get rid of these. You
only really need two files: a rat's tai³ file, and a half-
round type. Don't get big ones, since electronics work
involves tight spacesmost of the time.
For dealingwith wiTe,bending components, and other
light assembly work, you'n need needlenosepliers, diag-
onal cutters, and a wire-stripping tool for removing in-
su1ation. These run around $1 apiecefor averagequality
units; check the jaws for accurate alignment and smooth
action before buying anything, no matter how little or
how much the item may cost. Fancy automatic wiTe
strippers are available for about $8, but unless you're
doing small-scale production you'n find they're more
trouble than they're worth.
Next, your tool repertoire should include a medium-
34

32. and a Phillips-headscrewdriver,aswell
- ~. smalIjewelers'screwdrivers,lewelers'screw-
aleusuallyavailable(imported kind) for around
Theseale bandy for the setscrewsin knobs,
many other talents in the fields of poking,
~
algOwant a smalIcrescentwrenchfor tighten-
potsandscrewsand,althoughit isn't really
apair of visegrips,which is awonderfultool
. To round out your selecti'onof mechanical
-vise.
to solderingequipment.First i³em is a 25 to
pencil(soldering"iron" may imply a big
will probablybum out thoselittle ICs)and
tips. Look around for somethingwith a
smalItip, asyou'll saveyourself a lot of hassIein
-" that way.And get samesolder,too, but
underany circumstancespurchaseacid-coresol-
won't wark on electrical stuff, and caDeven
i³. Thekind you wantis 60/40 rosin-coresolder
the "multi-core" type). The "60/40" refers
. of metalsin the solder.Thinnersolderis
use,andcostsabout$15apoundat industrial
outlets.My favoritetype is ErsinMulti-Core.
find thin solder,the standardkind at Radio
additionto' soldering,you might algOwant a de-
tool. They comein all shapes,complexities,
costs,but the simplestkind is a squeezebulb
of timesI useplexig³assfor paneIs,and you
to work with it too. Plexig³asslooksneat,as
- fairly soft andeasyto work, but thereare
of specialtools you will need.Oneis a plexi-
. You canuseahacksaw,
J9 zipsthroughcutting big piecesand costs
$2, completewith instructions. Also, special
plexig³assdrill bits are required. Theseare available from
authorized plastics distributors (again, the Yellow Pages
will tell you where to look), and are tapered to make
drilling easy. Ordinary drill bits bigger than 1/8" or so
will tend to tear the plexiglass, producing nasty looking
holes that look like SOfie vicious animal was at work. I
use one 3/S" and one 1/2" plexig³assbit; for sma1lersize
holes I use a 1/8" standard bit and enlarge it willi a file
or a tapered reamer.
Finally you need a tool for testing called a Volt-Ohm-
Milliameter, or more simply, VOM (see Project No. 19
for instrtictions on how to useone). This little devicehas
a meter which allows you to read amounts of resistance,
amounts of volts, and current (not at the same time,
though). You can pick up one for anywhere from $5 to
$40; for most purposes the inexpensive type will do just
fiDe, so you might aswell opt for one under $20.
There are a few genera³ rules for taking care of tools.
nrst, if any of them come with instructions, read them.
Your drill will come with instructions about lubrication,
proper handling, and so on. Theseinstructions should be
followed, as should aDYdirections that come willi your
soldering iron or VOM. Second, never use a tool for a
purpose other than the one for which it was intended.
Screwdrivers make lousy chisels, for example, and sol-
dering irons are not available to little brothers or sisters
for woodbuming.
Drill bits respond well to sharpening at regular inter-
vals, and you may want to pick up an oilstone to keep
them happy. Also, never useplexiglassbit son aDYmate-
rial other than plexig³assunIessyou have an urge to run
out and bur a new bit.
Needlenosepliers are for fiDe work and wirebending.
Don't use them on big klunky jobs where you should be
using vise grips or the like, or you'll knock the jaws out
of alignment and have to get a new set of pliers. The
samegoesfor diagonal cutters; they're for cutting fme to
1
chassis
punch
~
-::..;.;::.-
.-,,', i---,
I
6
drill bit electric drill
~
rat-tail file
CI::::»)
half-round file
:::::::-
35

33. ~
needlenosepliers
.?
~hacksaw with blade
~u'~
~
~6

34. plexiglassscorer
'~~:::=::~:~=j ;---~=~~::
~~~=~~r===:Jwire strippers(manua³) ===::(=:====:(((==3==:~=~:::::::::'
standard
soldering pencil
--
~ ~:~~=====~rechargeable
soldering iron
(charger not shown)
J
7/
?o;
J ~,~~~~~~~~~=r;:~~~
pIexigIassdrlIIbit
0/
11:=-"=~~ :::x===:c
jeweersscrewdriver
""-J v
crescent wrench
3 -=~
Phi1lins-head screwdriver
E::~~:::::~==::=~:~:~;~~;;;;;;;;:::~' ,"I
. Rr',."urrlriv~r
/'
/./ /
7),-
Weller soldering irt>n
willi temperature-
controlled tip
'"Jt
(~ ~ L
vi~~
/spongefor keeping
tip clean
~7

35. thing requiringathree-wirecord.Theoneon thebottom
is ground,andthree-wireAC stuff is far saferthanstick-
ing on a three-to-two adapter and pluggingthat into
your wall. If you don't havea three-wireoutlet, usean
adapterbut take the wiTe coming out of the adapter
and connectit to the screwplateon your AC outlet, as
in Figure3-4. The screwshouldgo to groundandeffec-
tively doesthe samething asthegroundwiTeof athree-
wiTeoutlet. If you absolutelymustuseatwo-wiresetup,
eventhoughyou shouldn't, don't standon wet concrete
barefoot,okay?You'll zapyourselfuniessthedrill ispro-
perly insulated(most new onesale, but watch out for
SOfieolderones).
Whenyou drill, don't hold the object you're drilling
with your hands!Hold it with'avise,orvisegrips,orany-
thing suitable-shouldthe drill bit slipor skid,you want
it attackingtheviseandnot your hand.
Don't solderwith shortson if you're sitting down.
Sometimesthe rosin spits out andhits you on the leg;
not really bad,but not run either.Becarefulwhereyou
lay down your solderingiron-don't pul it whereit tan
bum through its AC cord (this happens-don't laugh!).
And watch for touchingthe wrong end of the iron. Be
careful, these things are hot (around 600-700° Faren-
heit).
After this stary talk, I shouldprobablymentionthat
I haveret to do anythingseriousto myself,but alot of
that is becauseI listened to all the safety tips when I
started.BecarefulanduseSOfiecommonsense,andyou
won't haveany trouble. Handsarepreciousto themusi-
ciao,andevenasmalIamountof carewill keepthemun-
scarredandunscathed.
"
~ Figure34
Adaptingthree-prongplug to twa-holeoutlet.
3R

36. Jtyou have never built anything elec-
tronic betore, Chapter 4 will help you
out considerably.It tellsyou what you
needto know to turn a pileot partsinto
anattractive,reliable,smoothlytunction-
ing unit.
SoIdering Technlque
processof building aDYelectronic device CaDbe
-into severallogical steps.Doing these steps
savesa considerable amount of time, and pro-
results. One step of planning caD savetwa
--_o.
l: Gather together any required parts, hard-
: Fabricatea circuit boardon which to mount
3: Mount the various components on your cir-
- solder them in place.
: Select an enclosure capable of containing the
-. board, pots, jacks, switches, batteries, and the
It's better to have too large an enclosure than too
~, asworkingin acrampedspacecanbe
5: Drill holesin the enclosureandprepareparts
thechassis;for exarnple,pot shaftsmay
6: WiTethecircuitboardto theoutboardparts.
7: Securelymount the circuit board in the
Sometimesit's best to plan for this (attaching
brackets,drilling h6les in the chassiswhere the
-- shouldmount) beforecompletingstep6.
Step8: Addknobsandlabel thevariouscontrolsand
9: Testthe thingout for properoperation,then
describeeach of thesestepsin detail in tJlis
; actually,we've already gone over step l, so
- start. But beforegoingany further,
-.-~_.- the subjectof soldering,asthis isper-
the most important part of putting togetherany
Proper solderingis vital to the successof your proj-
ects;a greatnumber,perhapsthe majority, of problems
with projectsaredue to poor solderinghabits.Hereare
four important pointsto considerwhensoldering:
l. Usethe right tools. Don't useironsover60watts,
and don't useacid-coresolderunderanycircumstances.
The only acceptablesolder is rosin-coresolder that's
expresslydesignedfor electronicwark. SeeChapter3
for additional information on choosinga solderingiron
andsolder.
2. Keep your solderingiron lip in good condition.
The cardinalTuleof tip careisto not let your iron sit in
a warmed-upcondition without havinga thin layer of
solder on the tip; otherwise,the tip will oxidize and
wark lessefficiently. Here'show I recommendgetting
your iron readyfor soldering:
-Wrap a tum of solderaroundthe tip of your iron
before pluggingit in or tuming it on. This way, when
the tip comesup to temperatureit will me³³the solder
and form the protectivelayer of solderwetalkedabout
earlier.
-Have a dampto slightly wet spongesitting next to
your iron (in a coffeecanlid, ashtray, or the like).Ju~
before soldering,wipe the tip acrossthe spongeto re-
move any excesssolder from the tip; this producesa
cleantip that createsbetterheattransferfor faster,maTe
efficient soldering.Whenyou're about to put the iron
asideafter solderingsameconnections,do not cleanorf
the tip fust; only cleanthe tip just before solderinga
connection.
3. Make surethesurfacesyou 'II besolderingtogether
are clean.For example,if you makeyour own circuit
boards,you'll fmd that copper forms a layer of oxida-
tion whenexposedto the air; thislayermakesit difficult
39