Controlling 110V devices with PC

[MasterOfTheHat]

Ok, I've seen the posts on X-10 and the Christmas light controller via the parallel port. Those are great and gave me some ideas/info, but I have some other, probably more elementary questions and another idea.

Can someone explain to me or point me to an explanation of how you can use low voltage, (5V from PC PSU), to control higher voltage, (110V on a 30A circuit), devices? From what I can see, the low voltage trips a relay which is in the 110V circuit, but how does that work?

I'd like to use something like this board to do some home automation, etc. Two reasons I like this one are that (1) it's controlled via USB and (2) it uses COM objects for control code, so you can write the apps in C#. Of course, I don't understand how, or even if, I can use the outputs on that device to control 110V switches.

Also, if it is possible to do this, is there something that will work like a dimmer switch? I mean, I could rig up a motor to a wall-mount dimmer switch, but I'm sure there is an easier/better method!

 

[BrainEater]

The device you are looking for is called a Triac.

It is capable of doing both switching and dimming.

I'm not sure if you can directly drive triacs with the board you've shown , but it should'nt be hard to achieve....

One thing to mention with using triacs : it's common practice ( and a good practice) to 'optically isolate' the AC high voltage from the low voltage dc control.

A quick gooogle should find you the required circuits.

gl !

 

[cpemma]

The device you are looking for is called a Triac...One thing to mention with using triacs : it's common practice ( and a good practice) to 'optically isolate' the AC high voltage from the low voltage dc control.

A 'solid-state relay' combines the opto-isolator and a triac in one package, or you can use the port to turn a transistor on and switch an ordinary mechanical relay. Simple 8-channel switcher.