Found in a 1980s telecommunications documentation, the circuit presented acts as a product detector. The modulator or mixer in the square may be that of the previous circuit.
This circuit is based on the small keychain that responded to the sound of a whistle and were...
This simple half-wave control using an SCR, which may be TIC106, has been obtained from a US...
Found in Popular Electronics from the 90s, this circuit reaches a few tens of megahertz. L1, C1...