230V AC TOGGLE SWITCH

Circuit diagram:

Parts:

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

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Comments:

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.

Notes:

• The circuit can be wired permanently to the mains supply as current drain is negligible.
• Due to transformerless design there is no heat generation.
• Low Gate-current Triacs are recommended.
• Obviously, other appliances can be powered in place of a lamp, provided their power dissipation does not exceed about 400W @ 230V
• 110-120Vac operation is easily obtained by simply changing C1 value to 680nF 250V. No further changes are necessary.
• In some cases, e.g. when the controlled device is far from the toggle switch, a pilot LED could be necessary for monitoring purposes. If so, disconnect pin #10 of IC1C from pin #11 of IC1D and wire a LED and its 1K series current limiting resistor across pin #10 of IC1C and negative supply.
• Warning! The circuit is connected to 230Vac mains, so some parts in the circuit board are subjected to lethal potential! Avoid touching the circuit when plugged in and enclose it in a plastic box.