Help Building a USB-Controlled USB Outlet?

Easiest way I can think of - get a FTDI 232R chip, hook up DTR to an opto-isolated triac driver, to a triac, to the power.

Then, at least on Linux, you can toggle DTR just by changing the baud rate to 0 (dtr off) or anything else (dtr on) via "stty" or the termios() functions.

The FTDI chips also have some GPIO pins you can use; in theory you can control six outlets with one chip that way (four GPIO, plus DTR, and RTS). You'd need to use their DLL and API to do that, though. Not a big deal if you know how to do any programming; the API is pretty straight-forward.

You can even get a vanilla USB to Serial adapter cable, and use DTR off that.

I have some triac circuits here:

But the opto-triac-power circuit is pretty common; you should be able to find schematics all over the web. I think the triac data sheets usually have schematics too.

Beware - messing with 120v power is dangerous. This isn't a beginner's project, although I think most beginners successfully pull it off anyway. I know I did :-)

and

You will also need a 5V wall adapter to power the relay board.

About $50 not counting the adapter.

The problem will be building the interface between the USB module and the relay card.

I can't tell from the specs in the link, but the USB module can probably be programmed to make pins go up and down. They claim to have "Easy Setup and Full Instructions".

I'm also guessing here, but the relay card probably uses a single pin per relay as control. When it goes to 5V, the relay closes, when it goes back to ground, the relay opens.

If you are lucky, the USB card will output enough power for the relay card, and you won't need the adapter/plug.

Send a question to the Futurlec guys here:

They have been very helpful to me in the past.

Good luck.

Regards, Bob Monsen

Have a look at Diolan.com

You can use phidgets

for software-controlled switched output via USB. You'd write your own program in C, .net, VBA, etc., and they give you the API to control the phidget output. I don't know if there are isolated outputs, but you could use an opto-isolator with a triac to switch the 120V power.

Do be careful -- you're messing with the 120 V main, and your computer and other gear is grounded. It'd be a good idea to power it from a ground-fault circuit while you're developing it.

--
Earl

If you instead use your serial port, you can control a solid state relay (see

with a modem control signal, DTR. Up = on, Down = off. The program to do this is trivial. You could even use one of these to make it easier to build:

If you get ambitious, you could even build something that would live on the serial line, and allow control of multiple devices using a multidrop.

If you really need it to be USB, you could go with something like one of these:

Here is a nice solid state relay you could use:

Regards, Bob Monsen

I'd suggest to hook-up a PIC 18F2550 (or something similar) to a solid state relay. You can have plenty of outlets controlled separately with only one USB input. Pros; well the USB stack is provided by microchip (many compilers provide their own as well) and it's going to be a breeze to control with a custom software (C#).

I can give you a few quick lines on where to look and what to do if you need details.