This Vox circuit uses a specific Motorola component. We found the circuit in the 1990 Linear Databook of the same company. The transistor must be in accordance with the switched load.
We found this circuit in an old American documentation. SCRs can be modern equivalent types. The...
We found this circuit in a 1990 documentation. The operational amplifiers are type 741 and the LED is...
This fast-acting circuit uses a 555. We found it in the November 1992 Radio Electronics magazine. The...