An Eternal LED Scarecrow
Recently, I wanted to try an electronic scarecrow in my lab window to scare off some birds (often nocturnal) that make a lot of noise and dirt. Although there are many options for building one, […]
Ultra-Sensitive Knock Sensor
Here’s the simple circuit of an ultra-sensitive knock sensor for microcontroller-based electronics projects. It’s in fact a piezo knock sensor monitor based on a single transistor, and designed carefully to work with 5V (or 3.3V) […]
BJT Switch & Microcontroller
Recently I got an unusual query from a newbie microcontroller hobbyist on how to drive an electromagnetic relay using a bipolar junction transistor (BJT). Admit it, analog electronics is not a piece of butter cake […]
A Cute Night Lamp
Once again, here is the circuit diagram of a little night lamp wired around the evergreen 555 tiny timer chip. The circuit, designed to run on a standard 6F22 9V battery, can be used as […]