powering devices, last problem

**nsmoller** · 03-08-2005, 05:37 PM

ok last little piece...

i want to power a dvd drive in the dash, as well as another usb hub...

i understand i pull off the 5v line for the usb, what about the dvd drive?

should i get a molex extender and tap into the 5v and 12v lines of one plug and send those 2 wires up front, then ground both?

i've never seen ide to usb stuff, how does the dvd get power?

how do i figure out whats negative and positive on a ac adapter plug thingy? i'm just gonna cut but i need correct polarity (of course!)

what do the other lines in the molex's do? (pictures would be great)

also, i was told to ground the computer to prevent line noise... take the black on a molex and send to ground? maybe i could use the same molex???

thanks for the help!

**Bugbyte** · 03-08-2005, 05:46 PM

Originally Posted by nsmoller

should i get a molex extender and tap into the 5v and 12v lines of one plug and send those 2 wires up front, then ground both?

That will work but you will now be grounding in two different locations. You ought to be able to find a 12 volt line up front, near the ignition, in a cigarette lighter line, perhaps.

To figure out polarity, get a digital mulitimeter (DMM). If you don't have one, you need one. It will also help you test for that 12 volt line.

**nsmoller** · 03-08-2005, 07:43 PM

regulated, unregulated? does that come into play?

they will have the same ground point (4 devices will have that same point)...

i run the wires from the trunk to have the pc control the turn on of this stuff, and i have a dssc so it cuts ALL power to usb stuff

thanks

**nsmoller** · 03-21-2005, 10:02 PM

Originally Posted by Bugbyte

To figure out polarity, get a digital mulitimeter (DMM). If you don't have one, you need one. It will also help you test for that 12 volt line.

ok...how?

**Bugbyte** · 03-21-2005, 11:02 PM

Well, you put the black lead on a ground point, set the multimeter to read voltage, and start probing wires with the red lead. The multimeter will read 12 volts when you find a good line.

If you're not sure how to use a multimeter, there ought to be instructions with the meter or do a google on how to use a multimeter. It's pretty simple once you've got one.

**fantomas** · 03-21-2005, 11:17 PM

the 12 volts should be regulated. i dont think the cig line puts out a regulated voltage..

**nsmoller** · 03-23-2005, 10:08 PM

so i buy a molex extender... tap into the thing, and run wire off the 5v and 12v lines, pull them up to the front of the car...

the 12v will go to another molex end, and into the internal dvd drive that will now be external... i will take the ground off that and run it to the ground up front...

the 5v will split and go to the positive line on the a/c adapter plug on the two usb hubs... the negatives will be ground at the same place as the dvd drive?

am i overpowering or underpowering any of those devices???

**Warpath** · 03-23-2005, 11:04 PM

Yea, the ciglighter is not a good regulated power source. In the past I have tried to power external usb drives off cig lighter. It would not survive engine crank, and would show up as "device unplugged" on the PC. I assume the best solution would be to power it off an opus or a regulated atx power supply. You can buy snap-together molex connectors at radioshack to make your own cable.
I once made a cable like this once. My external usb drive had a power port similar to a mouse plug (p/s2). So I cut a mouse cable and attached a molex connector to it. Just make sure the right voltage is going to the correct pins.

**vxcarpc** · 03-23-2005, 11:47 PM

Morex brand make power supply with everything you would need to power a ATX mobo + like 2 additional power devices like a cdrom and hdd.. comes with all the plugs you need and will power it well.

**nsmoller** · 03-24-2005, 12:32 AM

am i not being clear?

i am well aware of what a power supply can do...

i have the power supply in the trunk and a dvd rom in the front

do i need a wire for each of the in a molex to the front to power the dvd rom?
aka do i really need all 4 wires? can i do just one?