12 volt down to 6 volt.

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2door

2door

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Here's the question:
I need some advice on how best to reduce the 12 volts from my battery down to 6 or 8 volts without relying on high drain items like a ballast resistor. I found this great looking light that I want to use as a tail/brake light. It is a 12 volt LED clearance light made for semi trucks and such. I tried it and it gives plenty of light for a tail light on 6 volts and my idea is to use a switch activated by my rear brake caliper to bypass whatever device you might suggest to give it a full 12 volt for a brake light. Any ideas? I have a 12 to 6 volt ballast resistor but it draws a lot of amps and will take too much 'ooopmh' from my battery. There must be a solid state device that will accomplish the task without undue battery drain but I don't know what to look for.
Tom
 
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TheE

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For maximum efficiency, use a variable switching regulator like the LM2575 (adjustable version). It needs very few external components- the schematic is provided in the datasheet. If you want something "quick and dirty", go with an adjustable linear like the LM317. It will heat up more (wasting energy), though. I say adjustable because these regulators don't come in a 6V version, although I'm sure you can find one that does.

Another benefit is that you can vary the brightness of the lamp by adjusting the voltage.
 
Cabinfever1977

Cabinfever1977

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i would just use a household dimmer switch to adjust how much power goes to my lights.

they use dimmer knobs for interior and dash lights in cars and trucks.
 
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TheE

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Household dimmer switches use TRIACs, which only work with AC power. The ones in cars likely use PWM, which is another option. Using a variable LM2575 is the same idea.
 
wezwheels

wezwheels

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TheE said:
For maximum efficiency, use a variable switching regulator like the LM2575 (adjustable version). It needs very few external components- the schematic is provided in the datasheet. If you want something "quick and dirty", go with an adjustable linear like the LM317. It will heat up more (wasting energy), though. I say adjustable because these regulators don't come in a 6V version, although I'm sure you can find one that does.

Another benefit is that you can vary the brightness of the lamp by adjusting the voltage.
Click to expand...
good reply bud, that`.wee.s a perfect idea.
 
2door

2door

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Thanks guys and sorry for the delay getting back here to see the answers. I've been busy the last few days. I'll look into your suggestions.
To The E: Where would I look for a LM2575 regulator? Radio Shack?
To George: Thanks buddy. Those look like they'll do the job.
Tom
 
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TheE

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Idk if Radio Shack would sell them. A specialty electronics store might, though (I find Radio Shack is geared more towards consumer products these days). It also needs some support circuitry, so I'd check the datasheet to make sure you get everything you need. DigiKey Corp. | Electronic Components Distributor | United States Home Page also sells them, but once you factor in shipping, it might be cheaper to get a "total package" like Nash suggested.

Depending on your experience with electronics, you might want to look into a basic PWM circuit, which uses more readily available parts. I suggested the 2575 because it requires alot less understanding as to what is going on (and thus, less "debugging").
 
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