Computer control of AC devices

Step 13 Let there be light!

You now have control of two lights in this example instructable.

This setup could easily be modified to control the power to almost anything that plugs in. And RobotBASIC (www.robotbasic.org) can be used to make much more complex programs that, for instance, turn on electric devices based on a complex PC schedule.

Let there be light bulbs. :-)

Comments

[amalkady]

what sholud i use if i want 220 v??

[shortw]

How much power can you put through the board?

[indestructable]

The U451 is limited to about 2 amps at 110V. So at most each relay could control about 200 watts.

[whiplash]

then why does the usbmicron site say the relays are rated to 125v 10 amps ??

[ToddR]

From their website:
PCB trace widths limit the connections to the relays to about two amps - this should not be exceeded.

The board is what's limiting it, not the relays. Probably not that hard to work around if necessary.

[reoozeit]

My general knowledge of relays tells me that the 120v side is the side being switched on and off by the relay- essentially making it the same as the standard single pole switch in your house. And if those relay contacts are rated at 10 amps, they should be able to handle around 10 amps. The relays in components are typically purchased from other manufacturers and integrated into products by the electronics manufacturers. When they say differently about the connection to the relays being limited to 2 amps and are talking about the pcb, the 120v connection to the relays has some pcb trace going out to a separate terminal block- and that is true in this case (which would be a not-so-smart way to design a relay because it creates confusion about ratings, limits uses, and it could be done with terminals integrated into the relay to avoid all of this! ). In that case, a direct soldering of your wires to those contacts bypassing that pcb connection should suffice as described by author in comment below. Good luck, have fun, void your warranties, and BE CAREFUL! Don't hurt (enter your name here)!

[indestructable]

A reasonable work around is to use a heavy gauge wire to connect to the soldered relay connections on the bottom of the U451 USB relay board (in pictures above). You make direct heavy connections to the relays themselves to overcome the limits of the printed circuit board.