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Need a little help converting ac to dc for a home decorating project

Need a little help converting ac to dc for a home decorating project

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  #1  
Old 04-09-12, 07:57 PM
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Question Need a little help converting ac to dc for a home decorating project

I'm no electrician. I can handle wiring a lamp but figuring out what to buy to get what I want done is beyond me. I have the front end of an old car that I will be using in a gameroom. I want to plug the head lights into the wall. I tried a 12v. 1000ma DC walwart and it burned out in under an hour. Can anyone help me out and tell me what I need to get. I found AC to DC converters on ebay for halogen car lamps but I'm not sure if they are meant for 120v. Thanks.

Oh and does anyone know of anywhere I can get a flasher for a stop light or a flashing arrow sign?
 
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  #2  
Old 04-10-12, 03:04 AM
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Welcome to the forums! You have to consider the load when you buy a transformer. 1amp wall wart won't run lights that pull 8 or so amps in real life, so that's why it burned out. You need to get a higher amperage rated "regulated" power supply. Once you get that 12v set up for your lights, you could install a signal light flasher in line to operate your stop light flashing. Keep an eye on your total load so you don't overload your power supply.
 
  #3  
Old 04-10-12, 04:31 AM
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A typical car headlight is 50 watts, which draws a little over 4 amps at 12vdc. Two will draw 8.3 amps. Because it's not a good idea to load a power supply to 100% you'll need a minimum 10-amp supply, which will cost you $40 or more. You'll also find that those lights are so bright that you'll want a dimmer.

My suggestion would be to replace the headlights with standard 120-volt (AC) lamp sockets, bulbs, and a dimmer. Half the price; twice the convenience.

If you decide to ... ahem ... drive that car down that route, make sure you pay attention to proper wiring methods.
 
  #4  
Old 04-10-12, 07:59 AM
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I'm surprised they draw so many amps. I don't mind paying for a transformer. My original idea was to replace the lights with regular sockets but the lens is built into the bulb and it wouldn't look right without the lens. I'll search for a 15 or 20 amp 12v psu.

As for the flashing arrow anyone have an idea of a simple on off relay bank or something I can build or buy to switch an arrow with 6 sockets pulling 600 Watts on and off. I found little plug end blinkers but none rated over 150 watts.
 
  #5  
Old 04-10-12, 08:33 AM
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2 headlights at full brightness are going to throw off a lot of light...

I can't remember how these are constructed (yeah, it's been that long).....but would it be possible to somehow insert a lower wattage bulb into the reflector? By drilling or cutting out the filaments? Or possibly run them at 6V to reduce the supply requirement?
 
  #6  
Old 04-10-12, 08:41 AM
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Hey...it turns out they make replacement enclosures/reflectors for upgrading to more modern H4 bulbs.
Here's one site....H4 5 3/4" ROUND CONVERSION HEADLAMP

If it's a 2 bulb system there might be a savings even though the housing is a bit pricy. Might be able to just use a cheapo wallwart to run some LEDs?
 
  #7  
Old 04-10-12, 08:50 AM
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  #8  
Old 04-10-12, 01:26 PM
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Incandescent lamps work equally well on AC as they do on DC so there is probably no reason for the AC-DC conversion. Are these headlamps sealed beam units or do they have replaceable quartz iodine bulbs?
 
  #9  
Old 04-10-12, 01:53 PM
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You might want to look for a buck boost transformer with a 16-32 volt output and series wire the head lights. Also might consider a heavy duty 24v control transformer intended for 240v operating on 120v to produce 12v.
 
  #10  
Old 04-10-12, 01:58 PM
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But do you think the one I found will work? It supplies 12v 10 amps that should run two headlights without burning out right?
 
  #11  
Old 04-10-12, 02:59 PM
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Without knowing the current draw of the headlamps it is impossible to suggest any particular power supply.
 
  #12  
Old 04-10-12, 03:07 PM
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On our older tractors we have to use a step down unit to convert them to 12 volts and keep the original 6 volt lighting. I should think having one of them in line would drop the illumination to a more bearable degree. Of course they would be available at a tractor supply house.
 
  #13  
Old 04-10-12, 03:17 PM
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But two incandescent car lights won't pull more than 10 amps will they?
 
  #14  
Old 04-10-12, 03:21 PM
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Probably not more then 10 amps but we can only guess with out knowing the amps of the bulbs used.
 
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Old 04-10-12, 04:17 PM
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You might also want to consider an old computer's power supply.
 
  #16  
Old 04-11-12, 03:58 AM
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Originally Posted by antarchy
But two incandescent car lights won't pull more than 10 amps will they?
They could. My post was about a "typical" car lamp at 50 watts. Yours may be higher, which would pull more current. The wattage should be printed somewhere on the lamps. Use the formula Watts divided by Volts = Amps.

For my example it's 50/12 = 4.17 for each lamp. Multiply by two lamps = 8.34 amps.
 
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