Loads up to 150 mA can be controlled with this circuit from a 1967 publication. PUTs can be equivalent. The critical component is the 40M-ohm resistor which can be replaced by two 22M-ohm resistors in series. The time is given by multiplying the resistance of this resistor by the capacitor of 100uF. The value will be obtained in seconds, resulting in more than 1 hour with the proposed values (4,000 seconds).
