This circuit turns off after a time given by capacitor C1. This component can have from 1 to 1,000 uF depending on the desired time. The circuit is from an Electronics Now from June 1995.
This circuit can source 3 to 12 V with currents up to 500 mA depending only on the transformer....
Found in an Electronic Design of 1964, this circuit operates with control voltages from 0 to 12 V...
This circuit was obtained in a 1977 Radio Handbook. The transistor is from the era and the coils...