Does anyone know how much these cost to buy ‘retail’? My friend had one, to turn on his RAID power supply when the computer came on. Was just a USB cable, with male A at one end, and a male and female electrical pass-thru on the other.

Posted at 3:19 pm on Aug 18th, 2008 by AndrewNeo

Fuses and transient protection diodes don’t provide isolation, they’re just protection. The only isolation in this circuit is in the relay itself.

Posted at 4:33 pm on Aug 18th, 2008 by error404

I created something similar using a timer socket (the ones that let you set a time for a light to come on etc) for the relay and a usb cable hooked up to an opto isolator connected to control circuit on the pcb total cost < £10 (+ a 4 way).
Its not a solid state relay but it works well enough.

Posted at 6:24 pm on Aug 18th, 2008 by SL

This can be done for about $10 or less.
Use the usb cable to power an optoisolator that controls
a ac-dc converter that powers the relay.
only 4 parts needed.
Optoisolator
AC-DC converter
Relay
Diode

Totally isolated from the pc .
Or if you don’t care about isolation.
A relay and diode+usb cable is all that is needed.

Posted at 8:10 pm on Aug 18th, 2008 by mworks

why is it old computers had a power connector for this purpose, which only leads energy while the computer is running, and nowadays, no one provides this feature?

Posted at 8:33 pm on Aug 18th, 2008 by julian

My usb ports provide continual power if the computer has been shut down using the operating system. To stop power from going to the usb ports I have to flip the power switch on the power supply.

Posted at 11:28 pm on Aug 18th, 2008 by diy audio projects

@diy audio projects: some motherboards have a jumper to select what you want it or failing that you could hook it up to the 5v rail on your computers power supply. That should be off when the computers off ;).

Posted at 3:39 am on Aug 19th, 2008 by sl

Why not just use a mechanical relay? A 6V relay works fine with 5V in my experience.

Posted at 10:33 am on Aug 19th, 2008 by haarp

Costs $30 for a whole power strip that works the same way off USB, but they are currently out of stock:

http://www.theecostrip.com/index.html

Posted at 12:22 pm on Aug 19th, 2008 by djdropit

I have been working on a “real” USB device similar to this – i.e. with the computer actually able to control each outlet. The idea is to allow me to turn my printer on and off without having to reach around it all the time.

It’s fairly simple to do with an AVR microcontroller, so I am adding an IR interface to it as an extra feature.

Posted at 1:35 pm on Aug 19th, 2008 by MoJo

anything less than 500volts is actually low voltage

Posted at 9:03 pm on Aug 19th, 2008 by dan murrow

I have this site bookmarked. Thanks from Kredit

Posted at 7:22 am on Oct 2nd, 2008 by Kredit