This MOSFET circuit for microphone applications was found in the December 1969 issue of Radio Electronics magazine. The transistors are uncommon today.
In this circuit the LED lights up when the voltage drops below the value set in the trimpot. The...
This circuit was obtained from a Linear Technology manual from the 90's. The integrated circuits are...
Found in a 1995 documentation, this circuit is an alternative output to the previous circuits. The MOSFETs...