Michael likes his vintage organ KORG CX-3. It sounds good and keyboard feels right to play. But in early 70s there were no MIDI. But today almost any electronic music instrument comes with MIDI or other output interface. He decided to add a MIDI to CX-3 organ. For getting data you normally need to detect each key pressed. Luckily Michael found a great source on Internet with schematics where couple ICs are connected to keys that generate serial data stream. This gave him an access to keys by using couple of wires.

Next step is a midi interface. Attiny2313 seemed to be enough for generating MIDI. A home made PCB looks really great next to vintage organ schematic and it does job well. To see how to generate MIDI on AVR check out this resource on AVRfreaks.

Attiny2313 is simple and yet powerful micro. Manekinen built a 1 to 10MHz frequency meter using this chip. It measures frequency and displays result on seven 7-segment LED displays. In order to achieve 10MHz measurement range he had to use higher crystal than max 20MHz. With 22.1184MHz overclocking he was able to get it to desired range. Measurement is done using two timers – one for counting pulses of measured signal and another for timekeeping.

The accuracy of meter purely depends on crystal accuracy. So you should look for smaller ppm crystal oscillator to get better results. But for hobby purposes practically any decent crystal will do. Meter PCB is build so that it could be used as panel in any devices like signal generator or desk frequency meter.

Clap activated circuits has been for some time around. But most of them simply toggled the output. Pete have bought few cheap lamps and used them for his smart clapper project. He didn’t want to limit functionality with just turn on and off but added couple new interesting features.

As normally it toggles the AC switch when there are two claps within one second. If three claps are hared within one second them PWM dimming starts until fourth clap is detected. Additionally there is another relay which may be activated with laser beam. Laser is detected with photo-transistor. Device is controller by Attiny2313microcontroller which activates two 12V halogen lamps through transistor keys, one device is controlled using relay. Microphone captures sound, then amplifies, filters it and then comparator gives a pulse that goes directly to microcontrollers external interrupt pin. Small and effective circuit that adds fun to your house.

mkanoap from instructables is passionate about Munckin board game. To play this game a 10 sided dice to keep score for each player. So he decided to make it more convenient and constructed an electronic score keeper directly on card storage box.

For this he used Attiny2313 board where 8 seven segment LED indicators are driven by max7219. Score is updated with three push buttons that allow to select player and increase/decrease score. Great idea that could be adapted to other board games as well.