I found this circuit in a 1993 technical documentation. When we press the switch in parallel with the transistor for a moment, the timer is activated by making transistor Tr1 conduct current to the load. The transistor will drive for the time determined by R1 and C1, keeping the LED on in this interval. At the end of the programmed time, the transistor cuts off and the load no longer receives power. Tr1 can be a BD136 for currents up to 500 mA and the supply can be made with voltages from 6 to 12 V.
