Looking for a creative solution: USB bus still powered after CPU is off

**BlueGrimRX8** · 12-29-2004, 11:20 AM

I guess its my turn to revive this really old thread.....just a few clarifications after reading over and over everything in this thread.

1. It will be best to use a DPST relay correct?

2. I plan to run power from the 5V side of a Molex connector to a USB hub. Can I just cut the power cord that is supplied with the Hub and connect the 5V from the Molex connector to the positive and negative wires that I cut on the hub.

3. If I do #2 and complete the mod described in this thread, then no power will be provided to the Hub unless the CarPC is on?

4. I also plan to use the 12V side of a molex connector to power my lilliput monitor. This mod and the USB mod described above will not interfere with that correct?

Thanks for all the great help as always.

**rando** · 12-29-2004, 01:44 PM

Originally Posted by BlueGrimRX8

I guess its my turn to revive this really old thread.....just a few clarifications after reading over and over everything in this thread.

1. It will be best to use a DPST relay correct?

Yes

2. I plan to run power from the 5V side of a Molex connector to a USB hub. Can I just cut the power cord that is supplied with the Hub and connect the 5V from the Molex connector to the positive and negative wires that I cut on the hub.

Yes

3. If I do #2 and complete the mod described in this thread, then no power will be provided to the Hub unless the CarPC is on?

Yes

4. I also plan to use the 12V side of a molex connector to power my lilliput monitor. This mod and the USB mod described above will not interfere with that correct?

Yes

Thanks for all the great help as always.

You're welcome.

**Twowire** · 12-29-2004, 09:20 PM

I don't know if this helps, but I solved a similar problem by using a LED and a photo cell. I have a remote computer (server) with USB drives connected. My problem was not having access to turn on/off the computer and USB hard drives. I connected an isolated wireless switch, not the type you buy at Menards, Low's, Etc., to the power on/off button of the computer. I then connected a LED to the 5v line of a molex connector going to my hard drive, and optically couppled it to a light sensistive switch I made using an 741 op amp and a switching transistor connected to a 12 v relay. This is how it works: When I want to listen to music, I push my remote button on my key chain, the computer powers up and turns on the LED. This, in turn, activates my light sensitive circuit turning on my USB devices. When I am done I stop MC. I have Hibernation set for 5 minutes after which time, the computer shuts down. When This happens the LED goes out and the light sensitive switch deactivates, removing power from my USB hard drives. Works for me

**zootjeff** · 12-29-2004, 11:00 PM

You could just use a shutdown controller. That is one of the main features of the uSDC20D. When you don't want the computer drawing power, it doesn't. It goes down to .000050 amps. You can hook it up to your computer and your monitor. It even has an Aux output you can connect to amps and stuff.

-Jeff

**BlueGrimRX8** · 12-29-2004, 11:43 PM

I have the Opus 150W Power supply so I don't think that that is an option.....

Thanks Rando for the quick reply!!!!

**Taz** · 01-11-2005, 05:23 PM

Have not tested it,but think i works..

**rando** · 01-11-2005, 05:51 PM

@Taz: This solution was already discussed higher up in this thread. It doesn't work because it requires the Opus to tolerate the IGN line going high before the Battery line. It was discovered that the Opus power up only worked intermittently under such a scenario.

**BlueGrimRX8** · 01-17-2005, 06:06 PM

Worked like a CHARM, I just can't believe I made my first eletrical itemm!!!

**R32 JUhl** · 01-25-2005, 04:39 PM

Originally Posted by rando

Yes, that's correct. Here's a schematic.

<----

Rando,
I'll have to do some digging to find the schematic for my motherboard, but thanks for the info! I looked at the parts in post 125... can you verify those are sufficient for this mod? I really appreciate all you've done with this! Did you have any adverse effects from the hub not being powered up? I'm running a USB keyboard on the hub and I'm concerned the PC won't see it if the hub and PC are shut down for a few days.

Care to speculate why OPUS didn't take care of this for us?!?!

**Craig W** · 01-25-2005, 04:47 PM

i sent mine back to Opus and they fixed it by changing the firmware and something else.. turned it around in 1 day, didn't charge me shipping back to Canada either.. now my Opus 150w is completely off (including all USB devices) when i shut it down.

Craig