Re: Help Building a USB-Controlled USB Outlet?

Frank wrote:
<noreply@xxxxxxxxxxx> wrote in message news:K_udnQr1k4NwjOHanZ2dnUVZ_oimnZ2d@xxxxxxxxxxxxxxx
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


If you instead use your serial port, you can control a solid state relay (see http://en.wikipedia.org/wiki/Solid_state_relay) 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:

http://www.futurlec.com/Mini_RS232_TTL_5V.shtml

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:

http://www.futurlec.com/USB.shtml

Here is a nice solid state relay you could use:

http://cgi.ebay.com/Solid-State-Relay-SSR-24-220V-DC-40A-Heat-Sink_W0QQitemZ230254622839QQihZ013QQcategoryZ36328QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

Regards,
Bob Monsen

.

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