Alternating ON-OFF Control

by Tony van Roon

Use this circuit instead of a standard on-off switch. Switching is very gentle. Connect unused input pins to an appropriate logic level. Unused output pins *MUST* be left open!. First ‘push’ switches ON, another ‘push’ switches OFF. You can use 1/4 watt resistors if they are metal-film type. Any proper substitute will work for Q1, including the european TUN’s. For C2, if you find the relay acts not fast enough, leave it out or change to a ceramic cap between 10 and 100nF.

Alternating ON-OFF Control

Parts List

All resistors are 1/2 Watt and 5% tolerance.

R1 = 10K
R2 = 100K
R3 = 10K
C1 = 0.1μF, Ceramic
C2 = 1μF/16V, Electrolytic
D1= 1N4001
Q1 = 2N4401
IC1 = 4069, CMOS, Hex Inverter , or equivalent
S1 = Momentary on-switch