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.
In the 110 V network, capacitors of 200 V or more and in the 220 V network, capacitors of 400 V or...
The OC30 power transistor is an old type of germanium from the 60s. This amplifier, using this...
Found in Maxim documentation from the 90s, this circuit makes use of components from the period. The...