Thread: Need help with 12v cig. lighter device to run off of batteries&AC

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Need some help with this. I have a fm transmitter that runs off of 12v car lighter. I need to have it run of AC as well as batteries. (AC for when it's available and Batteries for portability.)

Any ideas on how I could put this together cheaply?

need to know how many amps/ milla amps this thing needs and ill make you a wiring diagram. should say on back.

Thanks!! however, I don't have any specs and I'm hesitant on cracking this thing open just yet. I will probably order another for that since they are soo cheap..

Here is a link to one off of Ebay..maybe this might help?:
Car MP3 Player Wireless FM Transmitter USB SD Card Jack - eBay (item 270460476934 end time Oct-23-09 10:08:25 PDT)

shouldn't have to open it , should say power info on back cover i think

This is a el cheapo thing from china. All I have is that same brochure you can see on the ebay site. Unfortunately, no specs..

Since this thing just plugs into any car cigarette lighter socket to work, wouldn't the specs have to match that?

I have a bare car lighter socket (female)..

Usually the cigar lighters in cars are 12 vdc, If you have a female lighter socket I would mount it through a piece of plywood or plastic and wire to a 12 vdc power supply according to the diagram on the spec sheet and just plug it in as you normally would.

well yes and no the cig lighter has a max load of 15 amps or so but i doubt that thing uses 1 amp. pick up the highest mila amp 12v dc converter you can find at say walmart or radio shack
if you go to radio shack you can pick up an 8 cell battery holder can be anything fom AA to d cells just know the D's will last longest but this will work
8 “AA” Battery Holder - RadioShack.com
and get 2 of these while your at it
RC 7.2V Battery Pack Connector Repair Kit - RadioShack.com

Sweet...I'll give it a try...thanks.

ok so first off this is what you need also from radio shack but can be found elsewhere notice the ma rating most important
13.5-30VDC/1000mA AC-to-DC Adapter - RadioShack.com
set to 13.5v dont worry anything from 12- 14v will work your device. cars while running actually have 14v not 12 like people think
the center pin on your cigarette lighter plug is + the wire connected to ring is negitive open it up cut the wires and mark positive with tape or somthing
the battery holder should be marked + and -
as well as the adapter plug end. just use the red for positive and black for negative tape them up with electrical tape and make sure they dont touch
and you should be able to switch from battery power to wall power by the connectors. hope this helps

Looks good..Thanks!