Turn your PC ON by simply knocking

Most PCs have have option that enable booting it on keyboard input. This gives ability for interesting hacks like knock enabled PC power up. Joonas have built a simple Attiny45 device that detects knock and sends PS/2 command to PC to turn it on. Knock is detected with piezo buzzer that is used as knock sensor. Since circuit is connected to PS/2 interface, it also provides power supply. knocks are detected by reading piezo sensor with microcontroller ADC input. ADC is implemented to sense signal level that is over threshold. And in order to to detect three successive knocks there is a timer based counter implemented. This is really simple implementation that can impress your friends. Continue reading

Attiny45 based reflow oven controller

If you want to solder SMT components professionally, you should use reflow oven. OF course, no one suggests using specialized oven which is really pricy and used in PCB houses where tons of boards are soldered. With a little bit of effort you can build pretty good oven that can solder small PCB batches. Zaggo simply purchased a toaster oven for about 40€. He also wanted to keep warranty, so he started building external controller that doesn’t mess with internals. Oven controller is based on Attiny45 microcontroller that comes with 4K of flash. He was able to squeeze in full PID algorithm along with minimal user interface. Temperature is measured by using 100k thermistor and oven is controlled with simple mechanical relay via transistor. Single push button is used to start program. Its performance is indicated with single LED. The circuit turned out to be very compact and easy to build with through hole components. Practically any simple oven can be turned in to reflow station without loosing warranty. Source code and other files can be downloaded from GitHub. Continue reading

Home built versatile servo tester

Servo motors can be used in many areas like RC modeling, robotics and control devices. They operate by applying PWM signal. By varying duty cycle we can change its rotating shaft angle. If deal with servo motors a lot you probably know that like any other device may be faulty or have flaws. So it is best to check them before installing. You can buy many types of servo testers for cheap, but Jan_Henrik decided to build one. His intent was to make it versatile. Servo tester is built around Attiny45 microcontroller which is programmed in Arduino language. Servos may come with different signal wiring, so he added three jumpers to select proper connector layout. PWM duty cycle is controlled with potentiometer. If you place any other resistive device like LDR, or thermistor instead of potentiometer you can use it for controlling fan speed or open/close vent hole. So this is great device that can be put in an hour. Continue reading

Tiny robots with microcontroller

18x12mm are dimensions of small driving robots that have AVR Attiny45 microcontroller on-board. These were developed by Naghi Sotoudeh. Small robots have two wheels – actually two vibrating motors from cell phones. They can be driven directly with MCU pins. Robots can be controlled with TV remote control. Small 3.6V NiMH battery servers as power supply that fits nicely under bot. And this is pretty much of hardware – no resistors or caps are used. Motors are driven with PWM signal so speed and turn can be programmed easily. Programming is done with bascomavr compiler. If you want to see it in action you’ll have to download 6MB video. Continue reading