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Old 04-13-2011, 02:52 PM   #1
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Resistor for cutting 12v in half

Is there a resistor that can be used to cut 12v in half?

I'm wanting to dim a couple of bulbs to half brightness.... is there a simple and inexpensive solution to this? The bulb is the 1141 size base.
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Old 04-13-2011, 03:17 PM   #2
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Do a search for a 12v dimmable switch in google . Lots of options.
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Old 04-13-2011, 04:08 PM   #3
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Yes, did that before I posted the original question.
I don't find $30+ inexpensive for the ability to dim a bulb.
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Old 04-13-2011, 04:13 PM   #4
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i would check Radio Shack they should be able to guide you in the right direction. Can't you just put a variable resistor in line like a dimmer knob in your house? they are cheap!
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Old 04-13-2011, 04:15 PM   #5
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Not sexy but works.

LED Light Dimming Switch Box 12V | Virtual Village - US
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Old 04-13-2011, 04:18 PM   #6
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Quote:
Originally Posted by scubieman View Post
that is what I was talking about, something along those lines.
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Old 04-13-2011, 04:25 PM   #7
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My previous searches turned up that box on ebay for around $3-4. Certainly an option, but a little bulky and exposed wires.

I'm looking to dim a living room light that we like to have on when watching tv. It's just too bright and distracting. I didn't know if lower wattage bulbs were available, or if adding a resistor (value??) would work. I'm looking for about half the light output.
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Old 04-13-2011, 09:31 PM   #8
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A 1141 bulb appears to be a 18.5 watt bulb. You could put a resistor in series to cut the light out put but it would have to be at least a 10 ohm 10 watt resistor and you will need one for each bulb you want to dim. And you won't be able to dim them. If you want the light output decreased without the ability to dim I would call a place like Easternlightbulbs.com (I have nothing to do with them). They should be able to tell you what bulb you could use to replace your current ones.
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Old 04-13-2011, 11:56 PM   #9
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Thanks kz08h5!

That's what I was looking for.

Actually, what I found out today is that a 5 ohm to 6 ohm, 10watt should approximately reduce the brightness by 1/2.

I'm going to assemble a small rotary switch and use three taps; full, 1/2, and 3/4 brightness. I think I found one that will mount right in the fixture.

I'm planning on using this on two light fixtures; one in the tv area, and one over the headboard of the bed. My fixtures are the typical 2 bulb/two position switch, so the second position on the fixture will always be full glitter.

I've happily replaced the first position bulbs with the 32 led boards in all the other fixtures in my rig, and very pleased with the results! I found that info in this thread: LED 12 volt lighting: Long term results

Thanks for the link to Eastern light bulbs. Eventually I'm going to get up to speed on LED's and make my 1/2 & 3/4 brightness bulbs using them.

Thanks again to all for your replies. This is a great forum.
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Old 04-14-2011, 01:00 AM   #10
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You can't reduce the brightness on LED bulbs by using a resistor. Also, those 10 watt resistors you have found will put out a lot of heat, so make sure you allow for that if you put them in the existing fixtures. Also at 5 ohms, you will only be putting about 4 volts to the bulb, probably won't even come on. I would look at a 2 ohm resistor, or make a reflector, or switch it for an led bulb with less lumen s.
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