Abstract: A method of making a microwave oven coin operative which includes cutting, just inside the shell of the oven, the input hot power line and connecting its two cut ends to the normally open contacts of a relay. A low voltage control circuit which comprises the secondary side of a step down transformer, a coin acceptor, a timer and a relay control coil is used to close the contacts. So that power can be provided upon demand to the control circuit, the primary coil of the transformer is kept always operative. Input thereto is supplied by the hot wire and the neutral wire. When fed coin(s) of the proper denomination, the coin acceptor energizes a timer circuit; and it in turn, sends power to the relay control coil, thereby closing the contacts and powering the microwave oven for the time interval up to that preset on the timer.