|The Mains 100-250V AC electronic On/Off switch,
controlled by a low-volt signal
I order to be able to automatically turn on and off the mini transformers of peripherals to my computer, I have dug out this electronics project from the late nineteen eighties for this pc mod.
It is a triac operated 220V AC switch, capable of 2 Amp without extra
heat fins, and as much as
It is controlled by a small opto coupler MOC3041.
An opto coupler has the advantage that the control signal is carried by
light, thus absolutely electrically separating the low-voltage side and
the high-voltage side of the circuitry.
On the low-voltage side is only a LED. In this chip it starts reacting at 3mA current which is reached at about 2.2V. So with a 5V or 12V power source you need a small resistor to lower the voltage to the right level, and you are set on the control side.
The MOC3041 also has the advantage of a zero-detection circuitry on the high-voltage side, ensuring an absolutely smooth ON switch of the high current side.
To get the two drawings to fit, you have to remember that the "pcb side" drawing will be mirrored when it is put on the copper side of the pcb.
A word or two about the AC connectors
R4 470 ohm - yellow purple brown