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an orderable switch which allows to pass an alternating current Answered

Hello instructables !

I am searching for an orderable switch which allows to pass an alternating current.

Which componant can I use ?



Jack A Lopez
Jack A Lopez

2 years ago

I am not sure what you mean by this adjective, "orderable". I am guessing that either means the kind of switch you can activate using a much smaller electrical signal. That is to say, order-able means command-able. Or maybe the word order-able means, buy-able; i.e. available to buy, from somewhere.

In either case, I think the switch you seek is either a relay, or a solid state relay.



A relay is a mechanical device. There is a little solenoid electromagnet that causes some switch contacts to physically move together to close the switch.

The solid state relay is usually built around a TRIAC,


which is a kind of semiconductor switch made to work with alternating current (AC). An important thing to remember about TRIACs is they only work with AC. Which is to say they do not work with DC, with direct current. With DC, they don't work because they won't turn off, unless something else interrupts the current. Note that with AC, the current goes to zero twice every cycle, and essentially that is magic that allows the TRIAC to turn off, when it is switching AC.

The other interesting thing you can do with TRIACs, is build a "dimmer" type circuit, and that is for AC loads that you want to kind of turn on with some fraction of the mains voltage, like 10%, 33%, 50%, 75%, etc, like for driving a AC lamp at different levels of brightness.

I am guessing the thing you want is just a relay, or solid state relay, because you have a AC load you simply want on or off.

However, if it turns out you want your load to be dimmable, and you want to know a lot more nitty-gritty detail about driving a TRIAC with a microprocessor, like Arduino, the author of this instructable,


seems to know what he's writing about.


2 years ago

It depends on the amount of current (amps) you are talking about. USA made switches have the voltage and amp ratings molded onto the switch. They are usually rated for AC current.

If you are looking for a switch to control a light fixture or small appliance that doesn't draw a lot of power, there are many inexpensive switches available

Something like a heater with a high amp draw or a big motor will require a more heavy duty switch.

A couple companies that sell many types of switches are mouser.com and digikey.com.