Abstract: Relay contacts provide the principal switching between a D.C. power source and the load. An SCR in series with a limiting resistor by passes the relay contacts during initial turnon to absorb the inrushing surge to capacitors of the load. Optical couplers provide isolation from a remote control. A transistor blocking oscillator is coupled between one optical coupler and the trigger of the SCR for turn on. Delay timing includes a collector-base capacitor at a transistor of the other optical coupler. A Zener diode couples the timing circuit to a transistor amplifier, which operates the relay. The turn-on circuit is then disabled. A turn-off pulse to the second optical coupler turns off the transistor amplifier, which opens the relay.