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

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.

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
rickharris3 years ago
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.
http://led.linear1.org/1led.wiz

Will do the calculation for you