The simultaneous presence of signals at inputs 1 and 2 of this circuit causes their trip and lock. The relay then remains docked, feeding or disconnecting an external load. To obtain the desired function, one of the 4 NAND ports with 2 inputs available on a CMOS type 4081 integrated circuit is used. The relay is 6V low current, but relays of other voltages can be used if they have tripping currents up to 50 mA. The 22 uF capacitor determines the coincidence time range for the trip, avoiding the action of transients. Depending on the operating range of the system, this capacitor must be changed and can be in the range of 100 nF to 100 uF.
