This circuit was obtained from HAM Radio magazine in an 80's issue. The FETs are types of the time and the frequency is determined by the crystal. The circuit operates at voltages from 3 to 9 V.
This interesting low current circuit uses only one diode to obtain a full wave rectified signal....
The circuit shown is from a 1993 documentation. It uses two FETs in an oscillating configuration that...
This circuit serves to prevent devices powered by 6 V from being left with a power cut. The...