Found in a 90s Popular Electronics, this circuit triggers a load from the audio signal applied to its input. The controlled load depends on the MOSFET.
This circuit can be adjusted between 0.2 and 2 V to trigger with chosen voltages comparing them with...
The configuration shown in the figure has been requested a lot by many readers who need a circuit...
In the figure we have an amplifier step configuration with a transistor suggested by a 1985...