This scheme is based on IC 555, will supply power to the load during the time interval up to 5 minutes depending on the setting of potentiometer R1.
It should be noted that not containing the transformer node to power the circuit consists of capacitors C1 and C2 and diodes D1 and D2. The time intervals of the timer are 0-5 min or a little more; the interval is determined by the charge of capacitor C3 through potentiometer R1, the resistance of which can be adjusted. To feed the AC power to a load in the circuit instead of the relay is a triac.
Feeding node IP capacitance of the capacitor C1 limits the current, there is no heat (it does not heat up). As capacitor C1 should be used metal foil capacitor, not an electrolytic. It is necessary to make sure that the condenser is designed for the correct voltage: the minimum 200 V, preferably at 600 V.
Zener diode D1 limits the voltage, the diode D2 plays the role of the rectifier, and capacitor C2 filters the ripple.
According to the materials Electronics Now; Publication: N. Bolshakov, rf.atnn.ru