230Vac Lamp Toggle Switch

Compact, transformerless circuitry

No relays employed

Circuit diagram:

230V ac Lamp Toggle Switch


R1____________470R   1/2W Resistor
R2_____________10K   1/4W Resistor
R3,R4_________100K   1/4W Resistors
R5______________1K   1/4W Resistor

C1____________330nF  400V Polyester Capacitor
C2____________100µF   25V Electrolytic Capacitor
C3____________100nF   63V Polyester or Ceramic Capacitor
C4_____________10µF   25V Electrolytic Capacitor

D1,D2________1N4007 1000V 1A Diodes
D3_________BZX79C12   12V 500mW Zener Diode
D4__________TIC206M  600V 4A TRIAC

IC1____________4011 Quad 2 Input NAND Gate CMos IC

P1_____________SPST Pushbutton


Due to the low current drawing, the circuit can be supplied from 230Vac mains without a transformer. Supply voltage is reduced to 12Vdc by means of C1 reactance, a two diode rectifier cell D1 & D2 and Zener diode D3. IC1A, IC1B, R2, R3 and C3 form a reliable bounce-free toggle switch operated by P1. R4 and C4, wired to pin #6 of IC1B reset the circuit (lamp off) when power supply is applied. IC1C and IC1D wired in parallel act as a buffer, driving the Gate of the Triac through R5.