This is the basic configuration of an operational amplifier sample & hold circuit. The FET and transistor are commonly used. The circuit is from an 80's documentation.
The integrated circuit used is not very common today. Transistors can be replaced by more modern...
This simple AM transmitter for very small ranges uses in the original version of the 1970s, a...
This self-oscillating voltage conversion circuit was found in an American 1980s documentation. The MOSFET...