I have an offroad trailer on which I want to change the existing 12 volt tube lights to accomodate led lights .the led lights run off a
4 volt rechargable battery how/what is the best way to change the voltage from 12v to 4v on each set of lights there are 4 sets in different areas I need to change the lights to accomodate the 12 voltage
Do a Google for LED drivers. There are ones around which will work over a wide range of voltages. Ready made and circuits you can build yourself. But for maximum efficiency you might have to go back to basics rather than adapt your existing ones.
But if all you want is working light stick with fluorescent. It's more efficient than LED at the moment.
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Dave Plowman dave@davenoise.co.uk London SW
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For 20mA?
A resistor works fine for indicator LEDs but is pretty inefficient for lighting ones. And when running off batteries this can matter.
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*Change is inevitable ... except from vending machines *
Dave Plowman dave@davenoise.co.uk London SW
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Well, I never said this was going to be efficient...just simple. A DC-DC converter would probably be more efficient, but based upon the original post, I think that may be overkill. In any case, now they can decide what is best.
On Sat, 22 Nov 2008 09:02:14 -0800, Caesar Valenti put finger to keyboard and composed:
It's not clear from the OP's description just how many LEDs are being supplied from the 4V battery pack, but an old mobile phone charger using an MC34063 PWM controller IC can output about 500mA. The output voltage can be reprogrammed by changing one or both of the feedback resistors.
For very high currents you could use a hacksaw to cut out the Vcore regulator from an old socket 7 motherboard. I have one that can be jumpered for 4V.
- Franc Zabkar
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Good candidate for 'Tip of the Month'! Old VRMs either sawed-out or on plug-in cards could make great supplies for lots of purposes.
Michael
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