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 technical documentation on thyristors from the 70s. The circuit is set...
This basic circuit is from an old documentation. The relay must be 50 mA maximum and must have a...
We found this circuit in documentation from Linear Technology of the 80s. The circuit uses...