XMDirect Cable

**R32 JUhl** · 11-26-2004, 12:56 PM

Originally Posted by jcdillin

I power my XMDirect from a 7812 voltage regulator hooked to my car battery.

You're using one of these? http://www.partsexpress.com/pe/showd...artnumber=7812 Hm... I'd like to know more about that.

**jcdillin** · 11-26-2004, 02:34 PM

Yeah thats the one, I only used it because my power supply is quite small and I didnt want to put that extra load on it. But I would not leave the XMD powered on all the time, I havent tried it but I dont want to come out to a dead battery. I actually have mine switched with the relay that turns on my inverter.

**R32 JUhl** · 11-26-2004, 03:21 PM

Originally Posted by jcdillin

Yeah thats the one, I only used it because my power supply is quite small and I didnt want to put that extra load on it. But I would not leave the XMD powered on all the time, I havent tried it but I dont want to come out to a dead battery. I actually have mine switched with the relay that turns on my inverter.

That's really interesting. I guess that could also be connected to the ACC output of the ign switch? I'm don't think my PSU has enough power to supply all the accesories we're putting on our acrylic housing. We have a few lights to really set it off along with a 150W Opus, P4 1.8G, 160GB SATA HDD and 512MB DDR SDRAM - single stick. Not to mention eight separate items on the USB including a seven port hub. So this might help us power some of the stuff we're bolting on. The XMD I was willing to run off of car voltage since it would normally run on that anyway...

Does this regulator require a heat sink?

**jcdillin** · 11-26-2004, 03:41 PM

yes, I had to heatsink it.

and yeah you could just attach it to the ACC line.

also I havent had time to check out the cable but I think the XMDirect can take unregulated power, because it has a voltage regulator inside it. But I didnt want to risk blowing the unit up from overvoltage and I was already building a regulator for my lilliput so I figured why not.

**R32 JUhl** · 11-26-2004, 03:45 PM

Originally Posted by jcdillin

yes, I had to heatsink it.

Cool. Thanks. I think you've helped me find a viable solution to my energy concerns.

Now even though the specs on that page say it needs 14.8V minimum, you're not having problems running yours with battery voltage? http://www.partsexpress.com/pe/showd...artnumber=7812

**jcdillin** · 11-26-2004, 03:48 PM

i'll double check the specs on mine, but it has not given me any trouble and it's been running the last 2 months now.

**R32 JUhl** · 11-26-2004, 03:53 PM

Originally Posted by jcdillin

i'll double check the specs on mine, but it has not given me any trouble and it's been running the last 2 months now.

If you find the specs on yours are different, I'd appreicate it if you could share your source.

Are you aware of one with a 5V output?

**R32 JUhl** · 11-26-2004, 03:57 PM

Originally Posted by jcdillin

i'll double check the specs on mine, but it has not given me any trouble and it's been running the last 2 months now.

Nevermind! I found one. http://www.partsexpress.com/pe/showd...artnumber=7805

Could you share tips on proper wiring?

**jcdillin** · 11-26-2004, 04:36 PM

it's pretty much as simple as that.

I added a 220uf polarized cap on the output of mine just to keep noise out of the line but for the XMD you should not need it.

and these are the units I am using

http://www.fairchildsemi.com/pf/KA/KA7812.html

**Grayscale** · 11-26-2004, 04:57 PM

Originally Posted by R32 JUhl

$85 sound fair?

Man, are you kidding me? They are 166MHz Pentiums! How much RAM do they have in them? And what kind of RAM is it? I was thinking more along the lines of $50...

Man, I would keep playing with that cable if I was you! As long as you don't get the power reversed, you can't really screw it up!