This GSM remote control project uses an AVR micro-controller (ATtiny2313) and the GM-47 GSM module to perform ON/OFF switching of remotely located devices through text message. It features four relay switches and eight digital inputs to monitor status of normal or reed switches. The SMS commands are password-protected.
SMS remote control
Dilshan Jayakody’s new project is a digitally-controlled 2.1 channel audio amplifier based on the TDA7377 AF power amplifier and PIC18F452 microcontroller. The amplifier provides 2 × 6W + 20W audio output power, ±14dB bass and treble controls, fully configurable +35dB bass booster for sub-woofer and satellite speakers and loudness switch.
DIY 2.1 channel audio amplifier
Word clocks are really cool. They tell the time using words. A neat thing about them is you can customize the display to show some personalized messages. Yes, TechKiwi’s new instructable is about making a personalized word clock gift, which displays the recipient’s name as well as some personalised messages such as birthday greetings. The project uses the Arduino Mega board as main controller and the DS3231 RTC chip for time-keeping.
Personalized word clock
With the advent of new audio technologies like CDs, Ipods and MP3 players, all of those old-fashioned cassette players and amplifiers have disappeared today. One of the many features missing on those old devices is wireless music streaming. This Bluetooth Ghettoblaster project by tomatoskins describes how to convert an old-time cassette player into a wireless streaming machine.
Bluetooth Ghettoblaster
Optoisolators, also known as optocouplers or photocouplers, are a very useful component in transferring electrical signals between two circuit blocks, while providing a complete electrical isolation between the two blocks. The key advantage of using an optoisolator is it blocks high voltages and voltage transients in one block being transferred to other, so that a surge in one part of the system will not disrupt or destroy the other parts. An opto-isolator connects the two blocks with a beam of light, which is modulated by input current. In this tutorial, Dan explains the basics of optoisolators and illustrates its working principle by making one using a light-emitting diode and a light-dependent resistor.
DIY optoisolator