I want to create a flash ring for my camera using an led array and have a few questions. My first one is going to be super simple so here goes.
Plan is 9v supply, with a simple on off switch, 20 white LEDs in parallel with 450 ohm resistors, using this method i calculate that 1/4 watts of heat dissipation should be ample for a 0.02 ma led
Q1. Does anyone see a problem with this method?
Q2. Is there another method that doesn't require massive heat sink resistors?
I want to create a flash ring for my camera using an led array and have a few questions. My first one is going to be super simple so here goes.
Plan is 9v supply, with a simple on off switch, 20 white LEDs in parallel with 450 ohm resistors, using this method i calculate that 1/4 watts of heat dissipation should be ample for a 0.02 ma led
I was thinking chains of 4 with a 1.7v forward voltage drop but if my calculation is right I would need 5 x 0.75watt heat sink resistors. At 0.02 amps x 4 x 9 = 0.72 and to change resistor values to 112.5(I'll go to the next value above to be on the safe side)
I could run 5 LEDs but that wouldn't leave much spare voltage for led5 after Vd has been taken into account. I was thinking of adding a 4.4mf (approx) cap to give me 2 seconds to charge for final focusing before taking any photograph as its for macro photography