This circuit was found in a 90s Electronic Engineering. The quadruple operational amplifier can be replaced by an equivalent. RL determines the tested resistance range.
Found in old documentation, this fuzz uses the 741 Operational Amplifier. Assembly is simple, but...
In the figure we have the simple way to use a low current switch or sensor to drive a high power...
This 3-channel transmitter for amateur analog TV from 902 to 908 MHz was found in a QST magazine...