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

**rando** · 08-22-2004, 12:29 AM

I just updated the schematic. The previous one had a slight typo and wont work.

**savante** · 08-22-2004, 01:20 PM

Not to jack this thread, or sidetrack it... but if you didn't want to go the relay route and had a self powered usb hub:

Based on the pinouts found at this page http://www.taltech.com/support/pins2.html

Could you clip the pin 1 on your hubs, Type B port as shown in the picture (I know its very blurry but take my word for it, its the right pin).

My thinking is that if its not taking the +5v from the USB bus it has to take it from the Power Plug... this way I dont have to mod the motherbooard-to-usb connection, the opus power supply or the usb cable and I dont have to use relays. All I will have to do is take 5V from the molex to a barrel plug and put it into the DC power of the hub.

Would this work? Or would the usb hub not even work without that pin connected?

**rando** · 08-22-2004, 02:49 PM

Yes, you can power your hub(s) from your PSU output connectors and yes you can disable the 5v rail of your USB bus -- in any way you want.

It wont solve the battery drain problem though it might make it a bit better. Click the link in my sig and take a look at the current readings I measured in message #18. The m10k itself will cause the Opus to pull ~86mA from your battery -- even with ZERO peripherals attached. You need to cut the 5VSB going into the computer OR the 12V battery input going into your Opus to stop this (assuming a BIOS patch cannot help). If you cut the 5VSB, the Opus current draw goes down to a more tolerable 7mA while off.

If the relay is a big deal, you can always build a solid state version.

**savante** · 08-22-2004, 03:18 PM

Thanks for the reply rando.
I hope I am not about to ask a stupid question... (its been a while since I worked with relays) In your schematic, the state the switches are in, is that the state they are in when the relay is energized, or is that a 'normally closed' state.

Again if I missed something, I apologize.

**rando** · 08-22-2004, 03:21 PM

Originally Posted by savante

Thanks for the reply rando.
I hope I am not about to ask a stupid question... (its been a while since I worked with relays) In your schematic, the state the switches are in, is that the state they are in when the relay is energized, or is that a 'normally closed' state.

Again if I missed something, I apologize.

Good catch! As shown, that would be the state when the relay is energized. You want to hook things up to the normally open side of the relay. I'll update the diagram shortly.

**savante** · 08-22-2004, 03:38 PM

And just for clarification, someone asked if it was a DPST relay.... but from my understanding you could use either a DPST or a DPDT with an 'open' circuited NC connection....

Is this correct applying to your schematic?

**archimense** · 08-22-2004, 04:40 PM

Originally Posted by savante

And just for clarification, someone asked if it was a DPST relay.... but from my understanding you could use either a DPST or a DPDT with an 'open' circuited NC connection....

Is this correct applying to your schematic?

Correct me if I'm wrong Rando.

But you can use a DPST or a DPDT without the normally open circuit connected.

The schematic that Rando posted currently shows DPDT relays without the normally open circuit connected.

**savante** · 08-22-2004, 04:46 PM

Originally Posted by archimense

Correct me if I'm wrong Rando.

But you can use a DPST or a DPDT without the normally open circuit connected.

The schematic that Rando posted currently shows DPDT relays without the normally open circuit connected.

Thanks, I thought you could use either or... but I think you have it backwards.

The contacts used would be the normally open contacts which only close when the coil is energized... the normally closed contacts would be left 'open'

**rando** · 08-22-2004, 04:57 PM

The schematic now shows normally open connections and a DPST relay (as I originally described). If you use a DPDT relay, then you'd wouldn't use the NC connections.

**savante** · 08-22-2004, 05:07 PM

Originally Posted by rando

The schematic now shows normally open connections and a DPST relay (as I originally described). If you use a DPDT relay, then you'd wouldn't use the NC connections.

Thanks for the clarification rando, the schematic looks great. I will definitely be using it for my reference.