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How to make a constant 5v power supply from 12v battery for 3 no. of 1watt smd led lights? Answered

I have lm7805 voltage regulator,
3 nos. of 1 watt smd led 3 to 3.7v 320ma power of each led.
I want to use these 3 led in a parallel circuit.
so please tell me the resistor value and capacitor value for making this circuit.


2 Replies

steveastrouk (author)2014-01-03

You can't. These LEDs will be destroyed in milliseconds if you wire them in parallel.

Put three in series, and try a 10 Ohm resistor

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rickharris (author)2014-01-03

What you need is a constant current supply.

Having the LEds in parallel isn't such a good idea as if one blows the other 2 get the "benefit" of the extra voltage.

Either each should have a suitable dropper resistor to limit the current or they should be in series.

Will do the calculation for you

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