USB device to activate switch

[dmehling]

I was wondering if there is some kind of USB device which can activate or close a switch.  I have very minimal knowledge of robotics and I'm not interested in custom building anything.  Also I am on a tight budget.

[galannthegreat]

Phidgets has that kind of stuff on their site, check it out http://www.phidgets.com/

[dmehling]

I'm not really sure that's what I'm talking about.  I looked at their products but all I see in terms of USB devices are ones for receiving input.  I need to control a switch from my computer.

[MaltiK]

I asked a similar question:

http://www.societyofrobots.com/robotforum/index.php?topic=6899.0

[dmehling]

I'm beginning to get the idea that such a thing doesn't exist but that it can be made with a microcontroller.  There are several inexpensive USB microcontrollers that could probably do the job.  But how exactly can I close a switch with a microcontroller?  The thread you directed me to read was concerned with controlling a solenoid or motor, but what I'm interested in seems a lot simpler.

[Razor Concepts]

A relay is a electronically controlled switch. Put 5v across the inputs of the relay, and a mechanical switch will close and connect two pins together. A microcontroller can provide the 5v to close the relay, activating the switch.

[cooldog]

I'm not really sure that's what I'm talking about.  I looked at their products but all I see in terms of USB devices are ones for receiving input.  I need to control a switch from my computer.

they sell usb switches there

http://www.phidgets.com/products.php?category=1&product_id=1014

[MaltiK]

thats around $50.00 USD there though...

[Admin]

Put 5v across the inputs of the relay, and a mechanical switch will close and connect two pins together. A microcontroller can provide the 5v to close the relay, activating the switch.

Not true . . . relays require quite a lot of current, but a microcontroller can only output like ~20mA. If you want to drive a relay, you'll need to do it with a MOSFET.