As you may well know, you can borrow USB standard 5 volt dc supply from any smartphone equipped with USB on-the-go (USB OTG) port. USB OTG is a hardware (and software) standard that allows you to connect a device to your smartphone/tablet through the micro USB port. Almost anything that uses a USB connector can… [Read More]
Universal 2S Li-Ion/LiPo Charger Module
This is a simple and 100% safe universal linear charger module for 2S Lithium-Ion (Li-Ion) and Lithium-Polymer (LiPo) batteries with the recommended constant-current/constant-voltage (CC/CV) charging algorithm. Initially charging takes place in the current mode and after reaching the target voltage the charging goes into voltage mode. At the moment the current is small, the battery… [Read More]
Little Rescue Light
During an unexpected blackout in particular, a simple light source can be a handy aid. With only two transistors, one photo resistor, and a few other components you can build an automatic emergency light. Here’s the circuit of my recently built, battery operated, little rescue light that lights up automatically in dark times! Circuit Diagram… [Read More]
Infrared (IR) Adapter for Smartphone – Part 1/2
Nowadays you can use your smartphone as an infrared remote controller handset to control compatible home appliances, a music system for example. Since most of the smartphones available today do not have an infrared sender, I recently developed a number of add-on hardware solutions to make your Android smartphone as a powerful infrared remote controller…. [Read More]
Simple Wireless Door Bell
Here’s an interesting circuit of a wireless door bell/buzzer for electronics students and hobbyists. The circuit is a short-range radio-frequency (RF) tone generator realized with the help of a cheap 433MHz RF transmitter & receiver module pair commonly available from almost all online electronics component shops. Apart from the RF modules, only a 555 timer… [Read More]
Tiny Tone Decoder Module
I’d made a number of tone decoder projects with the unique NE567 PLL tone decoder chip in 1990s, and most were published in Elektor Electronics (UK), Silicon Chip (AU) and Electronics For You (IN) magazines. Recently I found a batch of the nostalgic NE567 chips in a webshop and bought a couple of them for… [Read More]
Portable Snake Repeller
Afraid of snakes? Don’t worry, here is a portable electronic snake repeller solution to keep all poisonous snakes out of your surroundings. All you need is to simply put the device on the bare floor/soil to scare away many kinds of snakes, quickly and safely. Design of the little device is based on the proven… [Read More]
Little Melody Maker
Here is a simple do it yourself project of a little melody maker useful for all those hobbyists interested in making electronic toys or fancy gizmos for their kids. For extreme simplicity and flexibility, the circuit is built around the inexpensive microcontroller board ‘Digispark Attiny85 (Rev2)’. By default, the finished circuit will play the “twinkle… [Read More]
Poor man’s USB Rubber Ducky
I believe most readers are familiar with Hak5’s USB Rubbery Ducky. Well, simply it is a $45 key stroke injection tool, masked as a generic usb flash drive, widely used to hack unlocked computers. Computers recognize it as a regular keyboard and accept pre-programmed keystroke payloads at speeds beyond 1000 words per minute. In this… [Read More]
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 a fancy night light in your kids’ sleeping room. A built-in photo sensor in the circuit turns its ‘sleeping lamp’… [Read More]
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