Circuit Components Reference

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Your visual guide to all the components used in this course. Each section includes images, pinouts, and what the component does.

Need a datasheet? Google "[chip number] datasheet" - always available online!

Passive Components

Resistor

Resistor

What it does: Limits current flow and creates voltage drops
Measured in: Ohms (Ω), kilohms (kΩ), megohms (MΩ)
Key specs: Resistance value, power rating (usually 1/4W)
How to identify: Color bands (use color code chart)
Common values: 220Ω, 330Ω, 1kΩ, 10kΩ
Symbol:

Resistor symbol

Critical rule: Always use current-limiting resistor with LEDs!

Capacitor (Ceramic)

Ceramic Capacitor

What it does: Stores electrical charge, filters noise, creates timing circuits
Measured in: Farads (F), microfarads (μF), nanofarads (nF), picofarads (pF)
Polarity: Non-polarized (can be inserted either way)
Common values: 100nF (0.1μF), 10μF, 100μF
Used for: Decoupling, debouncing, RC timing circuits
Symbol:

Capacitor symbol

Capacitor (Electrolytic)

Electrolytic Capacitor

What it does: Same as ceramic, but higher capacitance values
Measured in: Microfarads (μF)
Polarity: YES - POLARIZED! Long lead = positive (+), short lead = negative (-)
Common values: 10μF, 100μF, 1000μF
Used for: Power supply filtering, timing circuits
Symbol:

Electrolytic symbol

⚠️ Warning: Connect backwards and it can explode! Always check polarity.

Diode

Diode

What it does: Allows current flow in only one direction
Polarity: Cathode (marked with stripe) = negative, Anode = positive
Common type: 1N4148 (signal diode), 1N4007 (power diode)
Used for: Reset logic, protection, rectification
Forward voltage drop: ~0.7V
Symbol:

Diode symbol

How to use: Current flows from anode to cathode (stripe side)

Active Components

LED (Light-Emitting Diode)

LED

What it does: Emits light when current flows through it
Polarity: Long leg = Anode (+), Short leg = Cathode (-)
Forward voltage: ~2V (red), ~3V (blue/white)
Typical current: 20mA
Symbol:

LED symbol

⚠️ Critical: ALWAYS use a current-limiting resistor (typically 220Ω-330Ω with 5V)

Resistor calculation: R = (Vsupply - VLED) / 0.02A
Example: R = (5V - 2V) / 0.02A = 150Ω → use 220Ω

Push Button

Push Button

What it does: Momentary switch that completes circuit when pressed
Pins: 4 pins - two pairs internally connected
Used for: Clock input, reset, user input
Symbol:

Button symbol

Note: Buttons "bounce" - they make/break contact multiple times. Needs debouncing!

Integrated Circuits (ICs)

Breadboard & DIP Package Basics

DIP IC Package

All ICs in this course use DIP (Dual In-line Package):

  • Two parallel rows of pins
  • Pin 1 marked with notch or dot
  • Pins numbered counter-clockwise from Pin 1
  • Always straddle the breadboard center gap

Standard pinout: Pin 1 (top-left) → Pin N (top-right) → Pin N+1 (bottom-right) → Pin 2N (bottom-left)

CD4026 - Decade Counter with 7-Segment Decoder

CD4026 IC

What it does: Counts 0-9 and directly drives 7-segment display
Package: 16-pin DIP
Power: Pin 16 = Vcc (+5V), Pin 8 = GND
Key pins:

  • Pin 1: Clock input (rising edge triggers count)
  • Pin 2: Carry out (goes high on 9→0 transition)
  • Pin 15: Reset (active high - tie to GND for normal operation)
  • Pins 3-11: Seven-segment outputs (a-g)

Pinout diagram:

CD4026 pinout

Used in: Module 1 & 2 (Counters and Clocks)

CD4017 - Decade Counter/Divider

CD4017 IC

What it does: Counts 0-9 with 10 separate outputs (one high at a time)
Package: 16-pin DIP
Power: Pin 16 = Vcc (+5V), Pin 8 = GND
Key pins:

  • Pin 14: Clock input
  • Pin 13: Clock enable (active low - tie to GND)
  • Pin 15: Reset (tie to GND for normal operation)
  • Pins 1-7, 9-11: Outputs Q0-Q9

Pinout diagram:

CD4017 pinout

Used in: Module 3 (Sequential Logic)

CD4040 - 12-Stage Binary Counter

CD4040 IC

What it does: Binary counter that counts in pure binary (not BCD)
Package: 16-pin DIP
Power: Pin 16 = Vcc (+5V), Pin 8 = GND
Outputs: Q0 (LSB) through Q11 (MSB)
Used for: Frequency division, binary counting, LED binary displays

Pinout diagram:

CD4040 pinout

Used in: Module 3 (Binary Counters)

555 Timer

555 Timer IC

What it does: Versatile timing IC - generates clock pulses, delays, oscillations
Package: 8-pin DIP
Power: Pin 8 = Vcc (+5V), Pin 1 = GND
Modes: Astable (oscillator), Monostable (one-shot), Bistable (flip-flop)

Key pins:

  • Pin 2: Trigger (starts timing)
  • Pin 3: Output
  • Pin 4: Reset (tie to Vcc if not used)
  • Pin 5: Control voltage (bypass to GND with 10nF cap)
  • Pin 6: Threshold
  • Pin 7: Discharge

Pinout diagram:

555 Timer pinout

Astable mode (oscillator): Add resistors and capacitor to generate clock signal

Used in: Module 2 (Timing Circuits)

7446/7447 - BCD to 7-Segment Decoder

7446 IC

What it does: Converts 4-bit binary (BCD) to 7-segment display format
Package: 16-pin DIP
Power: Pin 16 = Vcc (+5V), Pin 8 = GND
Inputs: Pins A, B, C, D (4-bit BCD input)
Outputs: 7-segment outputs a-g
Difference: 7446 = open collector, 7447 = active high

Pinout diagram:

7446 pinout

Used in: Module 3 (Decoders)

74LS107N - Dual JK Flip-Flop

74LS107 IC

What it does: Two independent JK flip-flops for building counters and registers
Package: 14-pin DIP
Power: Pin 14 = Vcc (+5V), Pin 7 = GND
Features: Edge-triggered, clear input

Pinout diagram:

74LS107 pinout

Used in: Module 3 (Flip-Flop Circuits)

74181 - 4-bit ALU

74181 IC

What it does: Performs 16 arithmetic and 16 logic operations on 4-bit inputs
Package: 24-pin DIP
Power: Pin 24 = Vcc (+5V), Pin 12 = GND
Inputs: Two 4-bit operands (A and B), function select
Outputs: 4-bit result, carry, comparator outputs

Pinout diagram:

74181 pinout

Used in: Module 5 (ALU Basics)

74283 - 4-bit Binary Full Adder

74283 IC

What it does: Adds two 4-bit binary numbers plus carry input
Package: 16-pin DIP
Power: Pin 16 = Vcc (+5V), Pin 8 = GND
Inputs: Two 4-bit numbers (A0-A3, B0-B3), Carry In
Outputs: 4-bit sum, Carry Out

Pinout diagram:

74283 pinout

Used in: Module 5 (Calculators)

28C256 - 32KB EEPROM

28C256 IC

What it does: Stores 32,768 bytes of data that persists without power
Package: 28-pin DIP
Power: Pin 28 = Vcc (+5V), Pin 14 = GND
Capacity: 32KB (256K bits)
Address lines: A0-A14 (15 address lines)
Data lines: D0-D7 (8-bit data)

Pinout diagram:

28C256 pinout

Used in: Module 4 & 7 (Memory and Lookup Tables)

Logic Gates (7400 series)

Logic Gate ICs

Common 7400 series chips:

  • 7400: Quad 2-input NAND
  • 7402: Quad 2-input NOR
  • 7404: Hex Inverter (NOT)
  • 7408: Quad 2-input AND
  • 7432: Quad 2-input OR
  • 7486: Quad 2-input XOR

Package: 14-pin DIP
Power: Pin 14 = Vcc (+5V), Pin 7 = GND

Example - 7408 (AND gate) pinout:

7408 pinout

Gate symbols:

Logic gate symbols

Used in: Module 4 (Combinational Logic)

Displays

7-Segment Display (Common Cathode)

7-segment display

What it does: Displays digits 0-9 (and some letters)
Segments: 7 LEDs arranged in figure-8 pattern (a-g) + decimal point
Types:

  • Common Cathode: All cathodes connected together → connect to GND
  • Common Anode: All anodes connected together → connect to Vcc

Segment layout:

7-segment layout

Pinout (may vary - check your specific display):

7-segment pinout

⚠️ Important: Each segment needs current-limiting resistor (220Ω typical)

Used in: Modules 1-3 (All counter projects)

Power & Tools

Breadboard

Breadboard

What it does: Temporary circuit prototyping without soldering
Power rails: Red (+) and Blue (-) lines run the full length
Component area: 5 holes connected vertically in each row
Center gap: For straddling ICs

Internal connections:

Breadboard connections

Pro tip: Test power rail continuity - some breadboards have breaks in the middle!

Jumper Wires

Jumper wires

Types:

  • Solid core: For breadboards (holds shape, doesn't bend easily)
  • Stranded: For connections that move (more flexible)

Color coding (recommended):

  • Red: Power (Vcc, +5V)
  • Black: Ground (GND, 0V)
  • Other colors: Signals

Sizes: Pre-cut or spool (strip and cut to length)

Power Supply

Power supply

What you need: 5V DC regulated power supply
Options:

  • Wall adapter (5V, 1A+)
  • USB power bank (5V)
  • Breadboard power supply module
  • 4× AA batteries (6V - works but slightly high)

Connector: Match to breadboard power rails

Multimeter

Multimeter

Essential tool for debugging!

Modes you'll use:

  • DC Voltage (V⎓): Measure Vcc, signal levels
  • Continuity (♪): Test connections (beeps if connected)
  • Resistance (Ω): Check resistor values

How to use:

  • Black probe → COM (common/ground)
  • Red probe → measurement point
  • Select appropriate mode

Quick Reference Tables

IC Power Pins

IC Family Vcc Pin GND Pin Voltage
CD40xx (16-pin) 16 8 5V
74xx (14-pin) 14 7 5V
74xx (16-pin) 16 8 5V
555 Timer 8 1 5V

Rule: ALWAYS connect power pins first!

Resistor Color Code

Resistor color code

Common values:

  • 220Ω: Red-Red-Brown (LED current limiting)
  • 330Ω: Orange-Orange-Brown (LED current limiting)
  • 1kΩ: Brown-Black-Red (pull-up/pull-down)
  • 10kΩ: Brown-Black-Orange (pull-up/pull-down)

Capacitor Code Decoder

Ceramic capacitor markings:

  • 104 = 10 × 10⁴ pF = 100,000pF = 100nF = 0.1μF
  • 103 = 10 × 10³ pF = 10,000pF = 10nF = 0.01μF

Electrolytic: Usually marked directly (e.g., "100μF 16V")