Thread: Question on powering USB devices off of 5v line on molex connector

Not trying to totally derail the thread here, but would it cause any problems with the OS, etc., to shut down power to the USB accessories while the pc is still powered on? I was throwing around the idea of building a simple 5v voltage regulator (possibly using something like these: http://cgi.ebay.com/5-National-LM267...em190028231041 ) to power a 7-port USB hub and a USB DVD drive in my dash. I could power this regulator with a relay triggered by the ACC line from my ignition switch, so the USB items would power down when I turn the key off, and my shutdown controller would put the PC into standby from the same trigger. Would this be feasable, or is there something else that I'm not taking into account here?

Originally Posted by PSYKO_Inc

Not trying to totally derail the thread here, but would it cause any problems with the OS, etc., to shut down power to the USB accessories while the pc is still powered on? I was throwing around the idea of building a simple 5v voltage regulator (possibly using something like these: http://cgi.ebay.com/5-National-LM267...em190028231041 ) to power a 7-port USB hub and a USB DVD drive in my dash. I could power this regulator with a relay triggered by the ACC line from my ignition switch, so the USB items would power down when I turn the key off, and my shutdown controller would put the PC into standby from the same trigger. Would this be feasable, or is there something else that I'm not taking into account here?

The link you provided would probably work, but there may be easier devices to use, the easiest among them being your DC-DC PS. It is fully regulated, and if you are not exceeded the specs, that would be the easiest.

There are also Point of Load devices on the MP3car store.

Also, while perhaps "old school", I like the LM338K regulator. It is adjustable, and will supply up to 5 amps I think (3 or 5, I forget), and needs just 2 external components. I am not sure how many parts the link you proveded requires. Also, the link looks prett SMD like, so it might be hard to work with.

As for powering the USB devices with the computer off, there should be no problem. In the long run, it MIGHT cause the device to "wear" quicker, but I doubt you will notice.

Michael

Originally Posted by Wiredwrx

Ya, it draws power, which will drain his battery.

Michael

yeah I figured that much but just wanted to make sure..

the thing is... how long does this have to go on until you actually drain your battery? I mean I drive my car every day and the most it stays in my driveway is less than 8-10 hours a day the most

-Emo

Emo - mileage will vary. For me, the battery gets low / potentially won't start if I don't run it for 2 days. That's WITHOUT any USB devices still being on while in standby, i.e. only the mobo is being powered for its standby state.