DC connectors.

Brycestro · 06-10-2007, 09:52 PM

Ok, i've finally got some time off so i'm getting some work done on the car. I've got a few devices that under normal circumstances would be operated in the home using an AC/DC adapter. So that i don't have to cut up the original cables for this to go in the car, i've gone out and purchaed a couple of DC connectors and plan to simply solder some wire running from them back to my OPUS power supply.

I just want to confirm something about the DC connectors... is it true to say that the outer part of the connector is in most cases used as the negative and the inner part of the connector as the positive? More specifically, i plan on using my own DC connectors for a:

Lilliput EBY-701
Soundblaster Audigy 2NX external sound card
random USB hub.

So if anybody has specific experience with making up their cables with a DC connector to run from that model lilliput or that model sound card and can confirm whether these two devices use the other part of the DC connector as ground that would be great. I believe i've read that in most cases the outer part of the DC connector is the one used as ground by devices, but i thought it'd be better to check if anybody knew and save myself the pain of frying something.

Thanks in advance, Bryce.

GoHybrid · 06-10-2007, 10:49 PM

generally, you are correct. the reason is, imagine you accidentally drop the connector and it hits metal on the chassis: which polarity would you want your barrel to be?

of course, you would be wise to verify that orientation by the icon on original power supply.

one other thing to be aware of is the DC voltage requirement of each device you're powering. Some devices only need 4.5V while others take 12V and sometimes upwards of 18. Make sure you can deliver the same kind of clean power your wall supplies did or you might be in for some trouble.

RedGTiVR6 · 06-10-2007, 11:04 PM

I wouldn't rely on a general statement for something like this.

For instance, the first CD-ROM case I purchased was reversed from what would be considered normal.

You should be able to look on the power brick or on the device it's self to see a diagram that will tell you how the plug is configured.

http://www.accesscomms.com.au/reference/polarity.htm

That link will show you what I'm talking about.

Brycestro · 06-11-2007, 12:46 AM

ah thank you ladies and gents, just what i was after. I've had a look on the power brick for the soundcard and found the symbol. In this instance, negative is the outside and positive is the centre. I'll have to have a look at the liliput later. Thanks very much for the help, very much appreciated, cheers, Bryce.

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