Powering small electrical unit in my car

[Shnorkiller]

Hi Guys,

So I have a specific appliance that I want to test out in my car. It needs to be powered whenever the car is on and turned off as soon as the car has been turned off. It needs to run off the battery and not out of the cigarette lighter so that it cant be fiddled with or unplugged.

I chatted briefly to an engineer the other day, he says a capacitor will do the trick (obviously I've come to the forum seeking confirmation) and that they're not too expensive.

So here it is (if capacitor is right option?): Where could I find a capacitor to power something that requires DC8-30V? (says that by the power jack on the device). The 2 prong plug says it outputs 9V (it then has a solid line with dotted line underneath) saying: 850mA


Any advice/suggestion would be greatly appreciated. If this works im going to want to give it a go in a few other cars so finding an affordable power solution is a must!

Thanks in advance!

 

[ponder]

Lol, wonder if this guy is fscking with you, did he say 'flux capacitor' by any chance?

So the device requires 3-30V DC input (You also mention 9V two prong plug)

I would simply look under the dash for a connector that is not use (or from the fuse box output side) and with a mulimeter find a 12-14V feed that's only on when the ignition key is turned to the 'on' position, if the ignition key is turned off you should have 0V.

 

[The_Ogre]

Capacitor? :wtf:

That guy must've been drunk or high or both!

 

[AstroTurf]

what ponder said.

 

[Ancalagon]

I don't think a capacitor will help. Read up on circuits and circuit components.

Capacitors are used to store charge - they act as buffers in a circuit. I think they can also prevent signals that are higher or lower than a certain frequency from passing, although I can't remember details.

I think cars run on 14V, which is slap bang in the middle of what the device can run on. What device is it?

Actually, here is a way you can sort this out quickly and easily. Phone a car audio fitment centre. They will know what has to be done.

 

[Tacet]

Capacitor? :wtf:

That guy must've been drunk or high or both!

I think he simply meant that the OP can use the existing supply in the car, and to put a cap in parallel with the supply rails to help filter out start-up transients.

 

[Shnorkiller]

thanks all for the replies, i'll get in touch with a car audio fitment centre and report back the findings