my collection of electronics projects, many involving an Arduino in one way or another
Building and testing the TJ-56-719 code practice kit. It can be used for CW/Morse code decoding and code practice, and also an IR decoder for characterising any IR controller. Includes clear and verified operating instructions.
The most minimalist acoustic levitation demo using an Arduino Nano to drive a pair of TCT40-16 ultrasonic transmitters.
Using an Arduino to automatically determine the polarity of ultrasonic piezo transducers.
Reviewing some common 40kHz 16mm ultrasonic transmitters and receivers TCT40-16T/TCT40-16R, including methods for testing polarity.
Review and test the 433MHz remote control unit 2202J that features two relays, can operate on mains AC or 5V USB, and can be programmed to behave in momentary, toggle, latching, mixed, or motor control modes.
Testing some push-button switches with built-in LEDs. I've used a CD4069 inverter-based latching circuit to demonstrate toggling the LED on and off.
A 3x3x3 LED cube animated with 512 different patterns generated by a 555 timer and CD4020 binary counter.
Introducing the CD4020 14-stage binary counter with a basic demonstration circuit.
Demonstrating the most minimal 555 oscillator configuration requiring just a single capacitor and resistor.
Introducing the CD4024 7-stage binary counter with a basic demonstration circuit.
Investigate acoustic levitation by building a cheap ultrasonic levitator kit that uses common 40kHz ultrasonic transmitters driven by STC15F101W microcontroller and a TC4427 power MOSFET.
All about double-pole, double-throw (DPDT) non-latching/momentary push-button switches.
A little 1d6 or 2d6 dice roller using the TM1638 and ATtiny85.
Celebrating the 55th birthday of the most evergreen IC of all time: the 555 timer, with a reproduction using discrete components. This is the Medium-Large 555 - a 555 timer built with BJTs and resistors, inspired by the work of the Evil Mad Scientist.
Demonstrating how a DEMUX gate may constructed solely from NAND gates.
Demonstrating how a MUX gate may constructed solely from NAND gates.
Demonstrating how an XNOR gate may constructed solely from NAND gates.
Demonstrating how an XOR gate may constructed solely from NAND gates.
Demonstrating how a NOT gate may constructed solely from NAND gates.
Demonstrating how a NOR gate may constructed solely from NAND gates.
Demonstrating how an OR gate may constructed solely from NAND gates.
Demonstrating how an AND gate may constructed solely from NAND gates.
Reverse-engineer a faulty YLD8-12X1W LED driver, diagnose the issue, but determine the fix is not worth the effort.
Using the new Open HamClock Backend (OHB) to give my HamClock client installation a new lease of life. Testing clients on Raspberry Pi, macOS, and Ubuntu.
Using the PLA 3D printing services available in Singapore's National Libraries - Bambu Lab P1S.
Building a 4-pole exclusive interlock using the CD4028 BCD to Decimal decoder, with a simple LED switching demonstration.
Using an Arduino to interactively solve cassidoo's interview question of the week (2026-02-09): using a rotary encoder to enter an array on an LED 8x8 matrix, dial-in a target digit on a 7-segment display, and then let it animate the recalculation of the matrix accordingly.
All about configuring the I²C on the Raspberry Pi. Demonstrates using the bus with BME280 and BMP280 environmental sensors attached, with examples of probing the bus with i2c-tools, and reading the sensors with python, using the smbus library.
A simple DIY adapter for the Raspberry Pi to mount the hardware for the BME280 environmental sensor, satellite, alarm, and countdown controls and indicators.
Examine the BME280 barometric pressure, temperature, and humidity sensor. Demonstrate its functionality with a common GY-BME280 3.3V module and an Arduino Mini with 128x32 OLED display.
Examine the BME280 barometric pressure, temperature, and humidity sensor. Demonstrate its functionality with a common GY-BME280 5V module and an Arduino Uno with 128x32 OLED display.
Review a common 12-16.8V DC to 220V DC boost converter module. Test it with neon and flame-effect lamp loads across the input voltage range, and reverse-engineer the circuit.
Examine the BMP180 barometric pressure and temperature sensor. Demonstrate its functionality with a common GY-68 module and an Arduino Uno with 128x32 OLED display.
Examine the BMP280 barometric pressure and temperature sensor. Demonstrate its functionality with a common GY-BMP280-3.3 module and an Arduino Mini with 128x32 OLED display operating at 3.3V.
Testing an XL4015-based buck converter with adjustable voltage and current controls and display. The serial interface is tested with a python script to capture current and voltage readings from the measurement board.
A common MP2307DN-based buck converter module that is extremely small and convenient for relatively low-power requirements under 17V.
An XL4015-based buck converter with adjustable-voltage control and selectable input/output voltage display.
Another common LM2596S-based buck converter module with adjustable-voltage control, operating at around 50kHz switching frequency.
A common LM2596S-based buck converter module with adjustable-voltage control, operating at around 50kHz switching frequency.
Demonstrating the 74LS47 7-segment common-anode LED driver with a simple 4-bit binary counter sequence.
About the 74LS161 4-bit Binary Counter with Asynchronous Reset, illustrated with a simple counter demonstration.
Building the CHA-81 LED Matrix Soldering Kit and investigate the principles of operation. A simple design that offers endless hours of fiddling!
Logging temperature and humidity with an Aosong AM2301 DHT21 sensor. Uses the Adafruit Arduino DHT Sensor Library directly.
Using the Adafruit Unified Sensor Library to log temperature and humidity from a DHT11 sensor.
Logging temperature and humidity with DHT11 sensor. Uses the Adafruit Arduino DHT Sensor Library directly.
All about the Raspberry Pi Pico 2, with a demonstration program created with the C/C++ Pico SDK and VS Code extension. The demo displays the the ADC internal temperature on a I²C 1602 LCD.
All about the Raspberry Pi Pico, demonstrated with a simple LED sequencing programmed using the C/C++ Pico SDK and VS Code extension.
Using MicroPython on an ESP-12E (4Mib ESP8266) to capture DS18S20 temperature measurements and log continuous readings to a cloud data collection service (Ubidots).
Using MicroPython on an ESP8266 (512kb ESP01) to capture DS18S20 temperature readings and log to a cloud data collection service (Ubidots).
A full-featured soldering practice board with a range of components (0603 , 0805, SO-8, SO-16) and a 64-LED matrix that displays a microcontroller-generated pattern when soldered correctly.