Do you like to play guitar? If yes, then probably you know that a significant time is spent when tuning instrument in order to play fluently. To tune a guitar you can depend on your ears or use a tuning device, or simply build one that is different from others.
As you know most of tuners use a microphone or other part to acquire sound frequency that is compared to a reference frequency. This way you know whether to strain or lose string. This particular device is interesting somehow, because it doesn’t use any microphones but couple LEDs. It is based on stroboscopic effect. Two LEDs are aligned side by side and are blinking at a frequency that string has to be tuned. When string vibrates, the two lines appear on fixed positions. If LED and string frequencies don’t match – lines appear to be blinking, or moving. The whole process is to tune string frequency until lines appear to be at fixed positions and not blinking. Stimmmopped is based on battery powered Atmega8 microcontroller with 7 segment LED indicator, two LEDs and couple buttons.
We recommend EasyEDA for circuit design and PCB prototype