How can I ? (electric question)

[holeinone1972]

How can I hook up a light that runs on 12v (car adaptor) to be able to run on 120 volt house current?

Rob

Forgive me, I know nothing about electric other than toasters, and bathtubs don't mix.
:lol:

[ElectronRider]

What exactly are you trying to do?

[capescuba]

What you would need is a setp-down transformer to change the voltage from 120-> 12v. You see them everywhere, little black boxes that plug into the phone, camera etc.

You could go to Radio Shack and pick up an adjustable one - where you can just select the voltage you need, but you need to make sure it can output enough current for the light.

Also, I believe you can buy adaptors that plug into an outlet and have a cigarette / car adaptor like outlet, I know I have seen them somewhere ...

[intranet]

Rob,

I probably have an extra 12 volt transformer if you need one. I use them to make moonlights with LEDs. I was going to call you about stopping over this week, I can help you out while I'm there if you need it.

Dave

[holeinone1972]

Originally posted by ElectronRider
What exactly are you trying to do?



Top secret.. :lol: :lol: :lol:

I'll let you know if it works, and does not turn out stupid. LOL

[ElectronRider]

the reason I asked, is your gonna have to crunch out the current requirement, and that can have an effect on which transformer you get. If you get a transformer that cranks out too much current, then your gonna have to build a circuit with a resistor or 2 to get it the way you need it. ( I smoked many leds tryin to do that on my motorcycle, finnally sat down and crunched numbers, and bought a 50 cent resistor, and solved my problems)

[holeinone1972]

I am going to use a 12 volt light that normally plugs into the car, and want to run it as a supplement that plugs into a regular outlet.

I already smoked 1 $35 dollar fixture, thinking I could simply attach a plug and plug it in.

Rob

[reb1058]

if it is just a light bulb you do not need to limit current. If it some sort of solid state device (LED,etc) then current limiting is required. To find out if the plug in wall unit is big enough, take the wattage of the lamp and divide by the voltage applied(in this case 12) this will give you the needed current. most wall transformers are rated by current. As an example, if your lamp is rated at 10watts/ 12 Vdc then 10/12=.834 amps or 834 uA The plug-in transformer will need to supply at least 834 milliamps to work properly. I would go with one rated at 1 amp to be sure. Hope this helps.

[buiryn]

From what it sounds like, what you need is a 12Volt DC adaptor.

If the light works connecting to a car adaptor, then all you have to do is figure out how much current it needs like reb1058 pointed out. Take the number of watts/12 to get the amount of current you need. 1 Amp = 1000 mA (milliamps) = 1000000uA (microamps). Radio shack sells these and you can always buy a larger current adaptor then you need, the only thing you waste is extra money for the adaptor. IE: You can use a 5 amp 12VDC supply to power a .010 amp led circuit. It's way overkill but works just fine.

How many watts are we talking about here? 12V DC adaptors get rather expensive once you go over the mass produced 1Amp transformers.

Buiryn