Electronics Bench

⚡ Electronics BenchLessons› Microcontrollers: Arduino, Pico and Raspberry Pi

Microcontrollers

Arduino Uno R3ATmega328P, 5 V, write C++ sketches

Raspberry Pi 4 (GPIO)40-pin header, Python 3

Raspberry Pi PicoRP2040, 3.3 V, MicroPython

Instruments

Multimeter (TH-M100)V, Ω, continuity, 10 A

Function generatorsine, square, triangle, saw

Logic probeHIGH / LOW / PULSE pen

Oscilloscope (2 channel)see voltages change over time

Logic analyzer (8 ch)see HIGH/LOW on 8 pins over time

Boards

Breadboard (830 holes)63 columns, 4 power rails

Power

Battery9 V, 2×AA or 12 V lead-acid

Bench power supply0–30 V with current limit

Solar panel 55 WVoc 24.5 V, Isc 2.83 A

Solar charge controller 10 A PWMpanel → battery → load, with LVD

DC-DC converter modulebuck-boost or LM2596 buck

Inverter 300 W pure sine12 V DC → 230 V AC

INA226 current/voltage sensorshunt + I2C power monitor

LM7805 5 V regulator7–25 V in → steady 5 V out

Passive

Resistorlimits current, ¼ W

Ceramic capacitorsmall values, no polarity

Electrolytic capacitorbig values, polarised!

Inductorresists changes in current

Potentiometerturn the knob: adjustable divider

Blade fuseblows on too much current

LDR (light sensor)resistance falls in bright light

NTC thermistor 10 kΩresistance falls when warm

Semiconductors

Diode 1N4007one-way valve for current

Zener diode 1N4733 (5.1 V)holds 5.1 V when reversed

NPN transistor 2N2222small current at B switches C→E

PNP transistor 2N2907pull B low to switch E→C

N-MOSFET 2N7000voltage on G switches D→S

P-MOSFET IRF9540 (TO-220)high-side power switch

Switches

Push buttonon only while pressed

Slide switch (SPDT)middle leg goes left or right

Toggle switch (SPST)simple ON / OFF

Logic switchclick: OUT = VCC or GND

DIP switch ×88 tiny on/off switches

Relay 5 V (SPDT)a small current switches a big one

Digital ICs

74HC00 quad NAND4 × NAND gate

74HC02 quad NOR4 × NOR gate

74HC04 hex inverter6 × NOT gate

74HC08 quad AND4 × AND gate

74HC32 quad OR4 × OR gate

74HC86 quad XOR4 × XOR gate

74HC74 dual D flip-flop2 × D flip-flop

74HC138 3-to-8 decoderone of 8 outputs goes LOW

74LS47 BCD to 7-segmentdrives a common-anode display

74LS90 decade countercounts 0–9 in BCD

NE555 timerclock / blinker / one-shot

CD4017 decade counterLED chaser: one of 10 outputs HIGH

74HC595 shift register3 wires in, 8 outputs

74HC161 4-bit countercounts 0–15 in binary

74HC14 Schmitt inverter6 × NOT with hysteresis

LM358 dual op-ampamplifier, buffer, comparator

LM393 dual comparatoris IN+ above IN−? (open collector)

Output

LED (5 mm)long leg = anode (+)

Active buzzer (5 V)beeps when powered

DC motor (3–6 V)spins faster with more current

Lamp 12 V 5 Wglows with power

7-segment displaycommon cathode or anode

12 V DC fan (10 W)spins on 12 V DC, ~0.85 A

WiFi router (barrel jack)12 V router, ~7 W

Phone / power bank (USB)charges from 5 V USB

RGB LED (common cathode)mix red, green and blue

LED bar graph (10)10 LEDs in one package

Lesson · 12 min

Raspberry Pi 4: react to a button

gpiozero’s Button turns on a pull-up inside the Pi, so you only need to wire the button between the GPIO pin and GND. when_pressed runs a function the moment it is pressed.

Wire the button
Wire one side of the button to GPIO27 (header pin 13) and the other side to GND (e.g. pin 14).
Run the program
Press it

Try a mistake

Wire the button between pin 13 and the 3.3 V pin instead of GND — with the pull-up already holding it HIGH, pressing changes nothing.

Selected

Nothing selected

Drag a part from the left. Drag from any pin to another pin to make a wire; drag a wire's end to move it (Shift-drag to start a new wire there). Scroll to zoom, drag empty space to pan.

Events

› Events (blown fuses, burnt LEDs, …) show up here.

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