This simple injector and signal follower employs a high impedance headset. Transistors can be of general use. The circuit is from old American documentation.
This circuit for signals around 4.5 MHz for old analog TV was found in the September 1992 Radio...
The circuit shown is a commercial electronic voltmeter sold in Japan in the 1960s. The circuit is fully...
This 80's circuit can be implemented with modern equivalent FETs with lower on resistance. The...