This Vox or sound activated relay was found in an American documentation from 1975. Equivalent transistors can be used, and the SCR can be a TIC106. The relay is according to the supply voltage.
We found this circuit in a documentation for 1977 American radio amateurs. The LM336 integrated circuit...
The frequency of this oscillator depends on the coil and the 10 nF capacitor. The circuit is from...
This circuit can work with the previous one generating signals, that can be decoded by it. The...