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.
In the figure we have a circuit with two operational amplifiers 741 capable of doubling the...
What differentiates this circuit from the previous one is the need for a much smaller current to...
This circuit was obtained in a Maxim documentation from the 90's. The circuit applies to...