We have many versions of biofeedback with the 555 IC on this site. This is another one. We found it in October 1986 Radio Radio Electronics magazine. The power supply must be isolated.
This simple electronic toy organ produces an interesting sound, which can be used by the most...
This SCR circuit was found in an American 1980s documentation. The circuit is still current,...
The sensor of this circuit can be any phototransistor and the SCR can be the TIC106. The circuit and...