Help Building a USB-Controlled USB Outlet?

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I am a novice and would like to build a 120V AC outlet which can be switched
on and off by USB. I'm not sure what all I will need and want to make sure
that I'm not trying to do something much harder than it sounds. My end goal
is to have a single plug where I could plugin a lamp, TV, power strip, etc
and have the power to that device controller by a PC via USB port. Now I've
seen some devices out there like X10-compliant home automation controls and
there has always been a severe limitation in one way or another. I would
love the pulg to be grounded but it doesn't have to be if that is a
complicating factor.

It seems to me that I need a relay which can switch the 120V on/off and then
need a USB controller to control the relay. And I have seen USB controllers
which have serial interfaces on them but then how to get from a pin or two
of a serial port to the relay is where it breaks down in my head. I'm not
sure what I need between the two or if that would even work. I can handle
the software part of it once I get a hardware solution idenfitied.

Can any of you pros offer advice to get me going in the right direction?

Thanks!
Frank

 

[DJ Delorie]

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:
http://www.delorie.com/house/furnace/

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

 

[TonyR]

Have a look at Diolan.com

 

[Earl Kiosterud]

I am a novice and would like to build a 120V AC outlet which can be switched
on and off by USB. I'm not sure what all I will need and want to make sure
that I'm not trying to do something much harder than it sounds. My end goal
is to have a single plug where I could plugin a lamp, TV, power strip, etc
and have the power to that device controller by a PC via USB port. Now I've
seen some devices out there like X10-compliant home automation controls and
there has always been a severe limitation in one way or another. I would
love the pulg to be grounded but it doesn't have to be if that is a
complicating factor.

It seems to me that I need a relay which can switch the 120V on/off and then
need a USB controller to control the relay. And I have seen USB controllers
which have serial interfaces on them but then how to get from a pin or two
of a serial port to the relay is where it breaks down in my head. I'm not
sure what I need between the two or if that would even work. I can handle
the software part of it once I get a hardware solution idenfitied.

Can any of you pros offer advice to get me going in the right direction?

Thanks!
Frank

You can use phidgets (www.phidgets.com) 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.

 

[CDESC]

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.

 

[Electro]

i was having a same problem but after reading the solutions now its fixed. Thanks