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 traditional preamp configuration with the common emitter configuration has a polarization setting...
The FET of this circuit of a 1971 publication may be the BF245. The circuit serves as a voltage...
We found this circuit in a 90s Electronic Design. Through a capacitor it can increase the growth...