We found this circuit in an old documentation. It can be elaborated based on modern components. The double transistor can be replaced by a matched pair.
This circuit turns off after a time given by capacitor C1. This component can have from 1 to 1,000...
This circuit is both simulation of the operation of a diode bridge and a test circuit for this...
This circuit, which can also be used with flashing LEDs as long as they have in parallel a charge...