Power Supply

[MartyO]

I need a twelve volt power supply that I can plug in to a 110v outlet that will let me power car headlights.

Thoughts? Suggestions??

 

[rockwithjason]

a quick search of amazon.com turned up about 1000 options. for head lights you will need a pretty stout one. i notices a 30a version on there for about 40 bucks.

 

[EOC_Jason]

An old PC power supply would probably be the cheapest.

Pending that, you can find a lot of power supplies on eBay...

 

[MartyO]

a quick search of amazon.com turned up about 1000 options. for head lights you will need a pretty stout one. i notices a 30a version on there for about 40 bucks.

I did not see the one you pointed to.

I saw this one:

http://www.amazon.com/dp/B007D6BHWE/?tag=atomicindus08-20

 

[s10xtremist]

A 55-watt headlight at 12 volts DC draws 4.58 amps. There is an amperage spike at start-up, so I'd get a power supply of twice the rated current draw to ensure it's sufficiency. I have no idea what PC power supplies put out, but there are plenty of simple plug-in adapters that'll work. Here's one: http://www.amazon.com/dp/B00B8TRF0A/?tag=atomicindus08-20

 

[volleyball]

PC power supply won't work. Most don't put out a lot of current at 12v.

 

[dogdog]

think that is too expensive. typical headlight is about 65 Watt? you would have needed 2 of that to power 10x 65Watt headlights or more if they are 100Watt bulbs no?


Maybe 10 of these (dependent on your wattage needs) cheap enough $13 each?.
If I remember correctly they used to have those 12V lamps that are power converted with toroid transformers. you wouldn't like the price for those.



http://www.amazon.com/DELED-110v-220v-Switching-Converter-Protections/dp/B00JX8ZD3E/ref=sr_1_27?s=electronics&ie=UTF8&qid=1406035508&sr=1-27&keywords=12V+power+supply

 

[Tscott]

Why not get a battery charger / jump starter. Should be able to power most anything you need.

Tom

 

[hilld]

Close, what you probably need is an automotive/motorcycle battery and a trickle charger unless you plan on running the lights full time, then you need a real charger. Most power supplies that can provide that kind of power, cost an arm and a leg.

With the battery you can power the lights for a longer amount of time and the charger can catch up when the lights are off.

 

[volleyball]

What are these lights for? If for decorating and you don't need all that light, get lights that takes bulbs and putting lower power bulbs in them.

 

[48RON54]

Why not get a battery charger / jump starter. Should be able to power most anything you need.

Tom

This. Though I'm running under the assumption you are just testing things and I could be completely wrong. I test most DC things with a simple cheap charger you can pick up anywhere.

 

[volleyball]

You can test bulbs with an ohm meter, so testing with a power supply seems a waste.

 

[justsam]

If all you are going to power are filament type bulbs, you can just use a step down transformer. The bulbs don't care about AC or DC. An old landscape transformer at 12 volts would do it.

 

[MartyO]

What are these lights for? If for decorating and you don't need all that light, get lights that takes bulbs and putting lower power bulbs in them.

I have an old GMC grill with great patina and three of the four head lights remaining. I want to mount the bumper either inside my shop or on an exterior wall and be able to power the lights when I am in the mood. As a result, I want to keep the bulbs in it that are already there.

I found a decent power supply on eBay that looks like it will do the trick but in the next day or two I will try an old, spare battery charger and see if that does the trick for me.

 

[MartyO]

If all you are going to power are filament type bulbs, you can just use a step down transformer. The bulbs don't care about AC or DC. An old landscape transformer at 12 volts would do it.

Good point! I did not think of this.

 

[hackwelder]

The lights will run fine on AC as was said, however they pull roughly 4 amps each so that would require an fairly hefty/expensive transformer rated for about 16A@12V or 200W.....FWIW the lights could also be wired in a series parallel combination to run on a 24V transformer (or even all 4 in series on a 48V transformer)....anyway around 200 watts and maybe about $40-60 in any case.
If you don't want them at full brightness a wimpier lower voltage transformer would work, the bulbs don't pull nearly as much current then.

 

[MartyO]

The lights will run fine on AC as was said, however they pull roughly 4 amps each so that would require an fairly hefty/expensive transformer rated for about 16A@12V or 200W.....FWIW the lights could also be wired in a series parallel combination to run on a 24V transformer (or even all 4 in series on a 48V transformer)....anyway around 200 watts and maybe about $40-60 in any case.
If you don't want them at full brightness a wimpier lower voltage transformer would work, the bulbs don't pull nearly as much current then.

I kind of want the dimmer, aged out look.

 

[hackwelder]

I kind of want the dimmer, aged out look.

9 volts would probably be about right for that...maybe wire all four in series and power with a 36V transformer? Not sure what the total power requirement would be but it would be MUCH less than the 200W 12V would require.

 

[maynard9089]

I would modify the headlight to accept something else such as LED. I wouldnt want bright lights in my face all the time. Just want the effect without the affect.

 

[big.jim]

a cb radio bench supply might be the thing

 

[Beemer533]

PC power supply won't work. Most don't put out a lot of current at 12v.

A typical 500 Watt Atx supply can provide well over 10 amps on the 12V rails.

I turned one into a bench supply using this wiki.. Pretty easy, works great. There are quite a few tutorials out there.
http://m.wikihow.com/Convert-a-Computer-ATX-Power-Supply-to-a-Lab-Power-Supply

I used an old one I had lying around, and I can easily pull 15A out of it. I only ever went that high so far when I first built it, but I have no problems pulling 5a from it regularly.

Here is a 500 Watt supply on Newegg for $40.. Shows 16a on one rail, 18a on the other.
http://www.newegg.com/Product/Product.aspx?Item=N82E16817148027

You shouldn't have any trouble getting 4a out of any atx supply that is operating correctly, even a 250 Watt one..

 

[rockwithjason]

I did not see the one you pointed to.

I saw this one:

http://www.amazon.com/dp/B007D6BHWE/?tag=atomicindus08-20

http://www.amazon.com/dp/B00D7CWSCG/?tag=atomicindus08-20

 

[s10xtremist]

I would modify the headlight to accept something else such as LED. I wouldnt want bright lights in my face all the time. Just want the effect without the affect.

This. You can even get direct-replacement LED bulbs. Then you could get away with a very small and common (~1-2 amp/12VDC) transformer.

 

[ForceFed70]

Another vote for a PC power supply. Super easy to modify and will provide all to current needed. Everyone has an old PC kicking around.

He could even use the 5V rail to get a dim light if he only wants the lights on for effect. Or wire the lights in series for 6V each.

 

[volleyball]

You will need a pc supply for each light unless you have a high power supply. You also waste a lot of power because of the unused +5v, -5v and -12v.
Now if you took a supply and engineered it to change the +5 to +12 it might be worth it.
You can take headlights and remove the filament and put in a 120v ac bulb and socket into it and do away with DC altogether. Put it on a dimmer too.

 

[jkwilson]

If you don't want them at full brightness a wimpier lower voltage transformer would work, the bulbs don't pull nearly as much current then.

You'd be surprised. Tungsten filaments have an unusal VI curve where it's really steep at low voltages and almost flat at higher voltages. A 10 to 25% voltage drop gives a very small current drop.

Before semiconductors, light bulbs were often used in electronic circuits to take advantage of that effect.

 

[hackwelder]

You'd be surprised. Tungsten filaments have an unusal VI curve where it's really steep at low voltages and almost flat at higher voltages. A 10 to 25% voltage drop gives a very small current drop.

Before semiconductors, light bulbs were often used in electronic circuits to take advantage of that effect.

Am aware of the non linear relationship, though even if current remained the same the power requirement would then drop off as the voltage, i.e. 25% less at 9V vs. 12V. Since I was curious how a headlight conducts at reduced voltage (and am slightly nerdy ;-) and had everything I needed on hand (a HL, a HL socket, a variac, and 2 DMM's) I decided to experiment and the results are below.
Also took a photo of the bulb at 6 volts and since the OP is looking for a dimmer decorative effect that would probably do the trick and a 80W 6 V transformer is only about $28 (4 bulbs would require about 60W @ 6V)

http://www.mouser.com/catalog/catalogusd/647/2287.pdf

 

[MartyO]

Am aware of the non linear relationship, though even if current remained the same the power requirement would then drop off as the voltage, i.e. 25% less at 9V vs. 12V. Since I was curious how a headlight conducts at reduced voltage (and am slightly nerdy ;-) and had everything I needed on hand (a HL, a HL socket, a variac, and 2 DMM's) I decided to experiment and the results are below.
Also took a photo of the bulb at 6 volts and since the OP is looking for a dimmer decorative effect that would probably do the trick and a 80W 6 V transformer is only about $28 (4 bulbs would require about 60W @ 6V)

http://www.mouser.com/catalog/catalogusd/647/2287.pdf

Holy smokes! I knew I should have paid more attention in science class!!

THANKS!!!!!

 

[hackwelder]

Holy smokes! I knew I should have paid more attention in science class!!

THANKS!!!!!

No problem at all, am glad I could help...I was curious anyway and FWIW I fool around w/ vacuum tube electronics as a hobby so the test gear was already on my workbench and the headlight was on a nearby shelf, only took few minutes.