The document describes the design and development of a low mid bell (peaking filter) circuit. Key points: - The filter is designed to have a center frequency of 500 Hz, gain of 15 dB, and a two octave range. - Calculations are done using Sallen-Key and Rauch filter designs to determine component values. Sallen-Key is selected. - PSpice simulations are run to verify the theoretical design meets specifications. - An Eagle PCB layout is created from the schematic. The board is then manufactured and components assembled.

1. Julio José Marqués Emán y Cristian Garrido Sánchez
INGENIERIA DE TELECOMUNICACIONES, IMAGEN Y SONIDO 23/12/2018
CIRCUITOS ELECTRÓNICOS
PEAKING FILTER
Circuitos Electrónicos

2. 1
ÍNDICE
Abstract………………………………………………………………… 2
Presentation of the project……………………………………………2
Filter design……………………………………………................2
Low mid bell (Peaking Filter) with PSPICE…………………………5
PCB circuit design with EAGLE ………………………………..7
Desarrollo PCB …………………………………………………………8
Assembly of components on PCBs ………………………………9
Bibliography ……………………………………………………………...
Declaration of original work ………………………..…………….
Abstract

3. 2
In this Project we´ll explain how we developed a Low Mid Bell which is a
Peaking Filter.
Our filter has a center frequency on 500 Hz, 15 dB of peaking filter gain and two
octave range.
At First , we Will do virtual verifications, afterward assemble the circuit and
finally physical verifications.
Presentation of the project
The objective of this circuit is to make a peak filter (Peaking Filter). In this
document we will show you step by step how we have been doing this project
(theoretical data, photographs, etc.)
Data that we know from a starting point:
- Fc = 500 Hz
- Gain : ±15 V
- Q fixed at 2 Oct
Filter Design
Next we will do calculations with Sallen-Key and Rauch, to see which one we choose:
H=
𝟏
𝐐
·𝐬
𝒔 𝟐·+·𝐬+𝟏
We choose that the capacitors are of 10nF, so we have that R0 will be:
SALLEN-KEY

4. 3
C1=C2=10nF
𝟏𝟎𝒏𝑭=
𝟏
𝟐𝝅· 𝟓𝟎𝟎· 𝐑 𝟎
𝑹 𝒐 =
𝟏
𝟐𝝅·𝟓𝟎𝟎·𝟏𝟎𝒏𝑭
= 31.8 K
We choose Rf as potentiometer, so we will try different values of R2, such that at the
beginning we will have the following values
R1= 1Ω R2= 2Ω Rb= 𝟑 −
𝟏
𝑸
Ω R5= 1Ω C1= 10nF C2=10nF Rf= 1Ω
We scale in impedance (Ro = 31.8 K ) :
R1= 1 · 31.8 k = 31.8 k
R2= 2· 31.8 k = 63.6 k
Rf= 1· 31.8 k = 31.8 k
Rb= 𝟑 −
𝟏
𝟐
= 2.5 2.5 · 31.8 k = 79.5 k
R5= 1· 31.8 k = 31.8 k
C1= 10nF
C2=10nF
Due to we have put the potentiometer in Rf, we will have to put a resistance Rs in
series with Rf so that when the circuit is with 0V it does not break..
Rs will have a value of: Rs = 22k
Valores normalizados
RAUCH
R1= 33 k Ω
R2= 68 k Ω
Rf= 33 k Ω
Rb= 82 k Ω
R5= 33 k Ω
C1= 10nF
C2=10nF

5. 4
𝑯 = −𝑯 𝟎 ·
𝟏
𝑸
· 𝒔
𝒔 𝟐 +
𝟏
𝑸
· 𝒔 + 𝟏
As before, we choose again the capacitors of 10nF, so our R0 will be worth the same
as before.. (R0 = 31.8 k)
The values of the components are as follows:
R1=
𝑸
𝑯 𝑶
= 0.4 Ω R2=
𝑸
𝟐·𝑸 𝟐·𝑯 𝑶
= 0.05 Ω R3= 2·Q = 4 Ω C1= 10nF C2 =10nF
We scale in impedance (R0=31.8 k)
R1= 𝟎. 𝟒 · 𝟑𝟏. 𝟖 𝒌 =12.72 k
R2= 𝟎. 𝟎𝟓 · 𝟑𝟏. 𝟖 𝒌 = 1.59 k
R3= 4 · 31.8 k = 127.2
𝐻0 < 2 · 𝑄2
𝐻0 < 2 · 22
𝐻0 < 8
𝐻0 = 5
R1=15 k Ω
R2=1.8 k Ω
R3= 150 Ω
C1= 10nF
C2=10nF
Normalized values
C1= 10nF
C2=10nF

6. 5
Observing the values that have given us so much in Sallen-Key and Rauch
theoretically, we decided to choose Sallen- Key
Low mid bell (Peaking Filter) con PSPICE
Now we will show the images obtained with PSPICE, showing how we have been
developing our project.
We have been testing several values in the resistance R2 until obtaining the
result that we wanted, to make that our filter goes from 0 V to 15 V, and we have
analyzed the circuit that gives us with PSPICE and the normalized resistances and scaled
in impedance. So much so that it's left us like this:
The Laplace commands are the ones that show the correct result and the seconds are
the ones that we have used for the manufacture of our filter. With PSPICE we are able
to verify that the theoretical calculations are correct and that our filter is well designed.

7. 6
PCB circuit design with EAGLE

8. 7
In orderto designthe PCBit isnecessarytohave the schematicdesignof the amplifierandto
knowthe dimensionsof the componentsthatwe are goingto use inour PCB, because their
dimensionshave tofollowcertainstandards,sothatourboard will be compatiblewiththe
componentsof the laboratory.Thatsaid,we createdthe schematicinEAGLE:
To simplifythe circuitlabelsare used,itisnecessarytoplace terminalsforVcc+,Vcc-,GND, In,
Out.We have chosento implementasingle GNDterminal,ratherthanaseparate one forentry
and one forexit.
In addition,4capacitorsare addedinparallel,these have the functionof filteringthe noise
coupledtothe powersupplyof the amplifier.
Some parts of integratedcircuitsare hidden,theseare calledimplicitcomponents.Withthe
invoke commandwe canshowthem.Thisis the case withthe AO powerpins.
To designthe board,we switchedtoPCBmode.There appearall the componentscontainedin
the schematic,withtheirterminalsjoinedbyyellow lines.
The firststepis to place the componentsina coherentlayout,thatis,youmustseek
optimizationof materialsandspace.Thisshouldbe done byavoidingthe appearance of empty
spacesinthe PCB.
The command ratsnesthelpsuswiththe processof placingthe componentsinthe pcb,each
time we use it,EAGLE optimizesthe automaticconnectionsbetweenthe components(the
yellowlines).
Next we join the terminals of the components with copper tracks, we must avoid that these
tracks cross. We will also avoid, as far as possible, that the tracks turn perpendicularly;
preferably we will draw more open curves.
As far as the thickness of the copper tracks is concerned, this should be 50 units.

9. 8
Once all thisis done we can groupthe componentstothe maximumtosave space. The copper
tracks mustbe locatedonthe underside of the PCBwhile the componentsare arranged on the
underside. To change the layer tracks, we can do it in the layer section. After changing the
tracks to the bottom face, you can see that their color changes from red (top) to blue
(bottom). After all these steps the design of the PCB is as follows:
PCB Development
Once made the PCB board with &quot;EAGLE";, we pass our design to reality,
capturing the circuit made with the program to the physical board on which the circuit
is going to be built, for it we have followed these steps:

10. 9
1- Printing on vegetable paper.
2- Cleaning.
3- Drilling.
- Printing on vegetable paper:
The day of the assembly we arrived at the workshop and the teacher already gives us
the impression on vegetable paper and our PCB as we have done in the EAGLE
program.
- Cleaning:
Once we have our plate,we will proceedtocleanitwithisopropyl alcohol verycarefully,we
mustcleanit withplentyof alcohol sothatall the protective plasticcomesoutof our plate,
bearinginmindthat once cleanthe protectorof the plate oxidizesquickly,soafterthisstep,
we will proceedtodrill.
- Drilling:
For thisstepwe will have touse drillsof differentdimensions :
- Resistors,capacitorsandamplifier (0.8mm)
- Inputterminals,outputandpowersupplyof the ( 1.25 mm)
- For the legsof the circuit(3 mm)
Assemblyof the components on the PCB
To finish this assembly, we will proceed to weld the components one by one, following
some welding guidelines:
1. Introduce the component in its corresponding hole.
2. Heat the leg of the element on which you are welding a little.
3. Once it is a little hot we bring a little amount of tin on the opposite side to the
one being welded and let a little tin be deposited on that side.
4. We did step three but on the opposite side.
5. You should have the same amount of tin on both sides.

11. 10
6. Cut out the part of the leg that protrudes from the tin we have added.
Final resulto f our plaque :

12. 11
Time domain simulation with PSpice

13. 12
Bibliography:
- Notes taken in class, from PoliformaT.
- PSpice manual.
- EAGLE Manual.
- Resistance manual.
Declaration of the original work:
Me, Julio José Marqués Emán, declare that the work is original and has not been
copied or made by others.