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# 220V AC Lamp Toggle Switch Circuit(BZX79C12)

2015-10-06 12:31
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This article describes the 220V AC Lamp Toggle Switch Circuit (BZX79C12). The principle is very simple, very practical. The circuit components can help you understand better grasp this principle. For example, in this circuit, you can go to find and buy these components: BZX79C12.

Compact, transformerless circuitry No relays employed

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.

#### Figure 1 220V AC Lamp Toggle Switch Circuit Diagram

Parts:

R1 = 470R
R2 = 10K
R3 = 100K
R4 = 100K
R5 = 1K
C1 = 330nF-400V
C2 = 100uF-25V
C3 = 100nF-63V
C4 = 10uF-25V
D1 = 1N4007
D2 = 1N4007
D3 = BZX79C12
D4 = TIC206M
IC1 = 4011NANDGate

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 @ 230V110-120Vac 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 pilotLEDcould be necessary for monitoring purposes. If so, disconnect pin #10 of IC1C from pin #11 of IC1D and wire aLEDand 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.P1 willSPSTPushbutton