When the power is cut off, this circuit keeps the flashlight on for a while, allowing it to be located. The circuit is from a Radio Electronics from September 1992.
The frequency of this type is oscillator is given by the RC network. Calculations can be found in...
This configuration, which appears in other points of this section and website with small...
This circuit is from the 1960 Mullard transistor manual. The transistors are germanium from the...