Like the previous circuits, this one uses a small speaker as a microphone and has two amplification stages with 600-ohm output.
With the circuit shown, you can have a fast response with a Darlington configuration. The circuit is...
We found this multiple thermostat circuit in July 1980 Radio Electronics magazine. It uses...
Mouser Electronics is already providing new MOSFETs EF SIHx28N60EF of Vishay series for voltages...