We found this preamplifier with 70 dB gain for microphones in American documentation from the 90's. Consumption is low and equivalent transistors can be used.
This 70 kHz oscillator is used to erase tapes in pre-recording. The circuit is from 1968 General...
We found this circuit in an old documentation for hams. In it we have the way to use a varicap to...
This sensitive touch circuit that triggers an oscillator uses only transistors. The circuit is...