This circuit uses an unusual sensor nowadays, but the configuration can be adapted to more modern types, as well as the operational amplifier. The circuit is from an 80's documentation.
The time the output is high (1) of a TLCSSB in the astable configuration depends on Ra and C. The...
Found in a publication from the 60's, this power supply has no regulation, but only current...
This short-range circuit can act as a wireless microphone. We got the schematic and the printed...