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.
We found this circuit in a 1998 documentation. It is based entirely on relays that must have...
This traditional complementary symmetry circuit provides 20 W of rms power at a load of 8 ohms...
Assembled with SMD components this circuit can be very small. The range is a few tens of meters. We...