Flyback Diode Direction: Build a Protected 5 V Relay Driver
Wire a flyback diode correctly across a 5 V relay coil. Follow the switch-off current path and calculate a transistor driver for a small relay.
Innovate, Experiment, and Electrify
Pico Ultrasonic Theremin: Turn Hand Distance into Sound
Turn distance into sound with a Raspberry Pi Pico and HC-SR04. Build the echo divider and explore pulse timing and PWM with full MicroPython code.
Choose an NPN Base Resistor: A 5 V LED Switch
Build a 5 V LED switch with a 2N3904 transistor. Calculate base current, understand saturation and choose a base resistor without guessing.
ESP32 Wi-Fi Signal Traffic Light: Find the Weak Spots
Build an ESP32 Wi-Fi signal indicator with three LEDs. Understand RSSI, choose thresholds and handle missing networks with a complete Arduino sketch.
Watch a Capacitor Charge: Measure a 4.7-Second Time Constant
Watch a 470 µF capacitor charge through 10 kΩ at 5 V. Predict voltage, measure the RC time constant and explain differences from ideal results.
ATtiny85 Reaction Timer: A Two-LED Pocket Game
Build an ATtiny85 reaction game with two LEDs and a button. Learn timer interrupts, debounce and state machines with complete C firmware.
ESP32 Smart Room: Motion, Light and Temperature Explained
Build an ESP32 smart-room prototype with PIR motion, an LDR and DS18B20 temperature sensing. Includes wiring, MicroPython code and calibration.
Why a Voltage Divider Drops Under Load: A 5 V Experiment
Build a two-resistor voltage divider, then add a load and measure the drop. Includes a clear schematic, worked calculations and beginner challenges.
Measure LED Current with a Voltmeter: A 5 V Experiment
Measure LED current using the voltage across a resistor. Build a 5 V circuit, compare three resistor values, and learn what your meter is really reading.
GoMining: Earn Bitcoin Without Hardware or Noisy Mining Farms
Bitcoin mining has always been associated with expensive hardware, noisy rigs, and high electricity bills. But times have changed. With GoMining, you can now earn …