Schematics, block diagrams, etc.

1. SCHEME

2. 3 TYPES OF SCHEME DIAGRAM
BLOCK DIAGRAM
SCHEMATIC DIAGRAM
PICTORIAL DIAGRAM

3. BLOCK DIAGRAM
A BLOCK DIAGRAM GIVES YOU AN OVERVIEW OF HOW THE DISCRETE CIRCUITS WITHIN
A DEVICE OR SYSTEM INTERACT. EACH CIRCUIT IS REPRESENTED WITH A “BLOCK” (A
RECTANGLE OR OTHER SHAPE, DEPENDING ON THE APPLICATION). INTERCONNECTING
LINES, SOMETIMES WITH ARROWS ON
ONE OR BOTH ENDS, REVEAL THE RELATIONSHIPS BETWEEN THE CIRCUITS.

4. FLOWCHART

5. SCHEMATIC DIAGRAM
A SCHEMATIC DIAGRAM (OFTEN SIMPLY CALLED A SCHEMATIC) INCLUDES EVERY
COMPONENT THAT A CIRCUIT CONTAINS, WITH EACH COMPONENT HAVING ITS OWN
SPECIAL SYMBOL. THIS BOOK IS DEVOTED MOSTLY TO SCHEMATICS.

6. PICTORIAL DIAGRAM
A PICTORIAL DIAGRAM, SOMETIMES CALLED A LAYOUT DIAGRAM, SHOWS THE ACTUAL
PHYSICAL ARRANGEMENT OF THE CIRCUIT ELEMENTS ON THE CIRCUIT BOARD OR
CHASSIS, SO THAT YOU CAN QUICKLY FIND AND IDENTIFY COMPONENTS TO TEST OR
REPLACE.

7. COMPONENT SYMBOLS

8. RESISTOR
RESISTORS ARE AMONG THE MOST SIMPLE ELECTRONIC COMPONENTS. AS THE
TERM IMPLIES, THEY RESIST THE FLOW OF ELECTRICAL CURRENT. THE VALUE OR
“SIZE” OF A RESISTOR IS MEASURED IN UNITS CALLED OHMS; TYPICAL REAL-WORLD
RESISTORS ARE RATED FROM ABOUT ONE OHM UP TO MILLIONS OF OHMS

9. CAPACITOR
CAPACITORS ARE ELECTRONIC COMPONENTS THAT HAVE THE ABILITY TO BLOCK
DIRECT CURRENT (DC), WHILE PASSING ALTERNATING CURRENT (AC). THEY ALSO
STORE ELECTRICAL ENERGY. THE BASIC UNIT OF CAPACITANCE IS THE FARAD
(SYMBOLIZED F).

10. INDUCTANCE AND TRANSFORMERS
INDUCTANCE IS A PROPERTY OF AN ELECTRICAL CIRCUIT COMPONENT CALLED AN
INDUCTOR. AN INDUCTOR IS A PASSIVE TWO-TERMINAL ELECTRONIC COMPONENT
THAT STORES ENERGY IN A MAGNETIC FIELD WHEN AN ELECTRIC CURRENT FLOWS
THROUGH IT. THE AMOUNT OF INDUCTANCE IN AN INDUCTOR IS MEASURED IN
HENRYS (H).

11. SWITCHES
A SWITCH IS A DEVICE, MECHANICAL OR ELECTRICAL, THAT COMPLETES OR
BREAKS THE PATH OF CURRENT.

12. DIODES
A DIODE IS A SEMICONDUCTOR DEVICE THAT ALLOWS CURRENT TO FLOW IN ONE
DIRECTION ONLY. IT HAS TWO TERMINALS, TYPICALLY CALLED THE ANODE AND
CATHODE. THE PRIMARY FUNCTION OF A DIODE IS TO CONTROL THE DIRECTION OF
ELECTRIC CURRENT.

13. DIODES
A DIODE IS A SEMICONDUCTOR DEVICE THAT ALLOWS CURRENT TO FLOW IN ONE
DIRECTION ONLY. IT HAS TWO TERMINALS, TYPICALLY CALLED THE ANODE AND
CATHODE. THE PRIMARY FUNCTION OF A DIODE IS TO CONTROL THE DIRECTION OF
ELECTRIC CURRENT.

14. CELL AND BATTERIES
A CELL OR BATTERY IS OFTEN USED AS A POWER SOURCE FOR ELECTRONIC CIRCUITS
ELECTROCHEMICAL BATTERIES WITH HIGHER VOLTAGE OUTPUTS COMPRISE MULTIPLE CELLS
CONNECTED IN SERIES

15. LOGIC GATES
ALL DIGITAL ELECTRONIC DEVICES EMPLOY SWITCHES THAT PERFORM SPECIFIC
LOGICAL OPERATIONS. THESE SWITCHES, CALLED LOGIC GATES, CAN HAVE ANYWHERE
FROM ONE TO SEVERAL INPUTS AND (USUALLY) A SINGLE OUTPUT. LOGIC
DEVICES HAVE TWO STATES, REPRESENTED BY THE DIGITS 0 AND 1. THE 0 DIGIT
IS NORMALLY CALLED “LOW” AND THE 1 DIGIT IS CALLED “HIGH.

16. A LOGICAL INVERTER, ALSO CALLED A NOT GATE, HAS ONE INPUT AND
ONE OUTPUT. IT REVERSES, OR INVERTS, THE STATE OF THE INPUT. IF
THE INPUT EQUALS 1, THEN THE OUTPUT EQUALS 0. IF THE INPUT
EQUALS 0, THEN THE OUTPUT EQUALS 1.
AN OR GATE CAN HAVE TWO OR MORE INPUTS (ALTHOUGH IT USUALLY
HAS ONLY TWO). IF BOTH, OR ALL, OF THE INPUTS EQUAL 0, THEN THE
OUTPUT EQUALS 0. IF ANY OF THE INPUTS EQUALS 1, THEN THE OUTPUT
EQUALS 1. MATHEMATICAL LOGICIANS WOULD TELL US THAT SUCH A
GATE PERFORMS AN INCLUSIVE-OR OPERATION BECAUSE IT “INCLUDES”
THE CASE WHERE BOTH VARIABLES ARE HIGH.
AN AND GATE CAN HAVE TWO OR MORE INPUTS (ALTHOUGH IT USUALLY
HAS ONLY TWO). IF BOTH, OR ALL, OF THE INPUTS EQUAL 1, THEN THE
OUTPUT EQUALS 1. IF ANY OF THE INPUTS EQUALS 0, THEN THE OUTPUT
EQUALS 0.

17. AN OR GATE CAN BE FOLLOWED BY A NOT GATE. THIS COMBINATION
GIVES US A NOT-OR GATE, MORE OFTEN CALLED A NOR GATE. IF
BOTH, OR ALL, OF THE INPUTS EQUAL 0, THEN THE OUTPUT EQUALS 1.
IF ANY OF THE INPUTS EQUALS 1, THEN THE OUTPUT EQUALS 0.
AN AND GATE CAN BE FOLLOWED BY A NOT GATE. THIS COMBINATION
GIVES US A NOT-AND GATE, MORE
OFTEN CALLED A NAND GATE. IF BOTH, OR ALL, OF THE INPUTS EQUAL
1, THEN THE OUTPUT EQUALS 0. IF ANY OF THE INPUTS EQUALS 0,
THEN THE OUTPUT EQUALS 1.
AN EXCLUSIVE OR GATE, ALSO CALLED AN XOR GATE, HAS TWO INPUTS
AND ONE OUTPUT. IF THE TWO INPUTS HAVE THE SAME STATE (EITHER
BOTH 1 OR BOTH 0), THEN THE OUTPUT EQUALS 0. IF THE TWO INPUTS
HAVE DIFFERENT STATES, THEN THE OUTPUT EQUALS 1.
MATHEMATICIANS USE THE TERM EXCLUSIVE-OR OPERATION BECAUSE
IT DOESN’T “INCLUDE” THE CASE WHERE BOTH VARIABLES ARE HIGH.

22. END