# 10 led circuit help(white and red)

Discussion in 'LEDs and Optoelectronics' started by sage2605, Feb 17, 2013.

1. ### sage2605

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Feb 9, 2013
Hi.i have a project that has 35 leds (in all) a mix of 16 red-10 white-9 rbg (i have a seperate post for RBG)..so to start the leds are red-2.0-2.2v 20ma..white-3.2-3.4v 20ma..what is the best way to power this many at once without a huge power supply.thank you

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Aug 13, 2011
Last edited: Feb 19, 2013
3. ### sage2605

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Feb 9, 2013
well some of the lights will not be on all the time. the white lights will come on when I flip a switch along with the others. what I have to make a different circuit to compensate for some of the lights not being on all of the time. reds and whites come on separately

4. ### sage2605

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Feb 9, 2013
Can someone help me with rhe circuit.what resistors capacitors to use and such?

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6. ### ICGengineerTech

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Aug 15, 2012
Last edited: Feb 20, 2013
7. ### sage2605

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Feb 9, 2013
Thank you .ive tried it and it says 12v isent enough for just 10 leds 3v 20ma. what am I doing doing wrong?

8. ### ICGengineerTech

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Aug 15, 2012
I tried and...

I gave it a try and put in your numbers:

Source Voltage: 12
Diode forward voltage: 3
Diode forward current (mA): 20
Number of LEDs in your array: 10

What I got was a few options for arrays. I might not be understanding the whole problem here. Do you have to have each diode capable of turning on and off independently of each other?

~Bill

9. ### duke37

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Jan 9, 2011
With 3V/led, three leds = 9V To get 20mA and a voltage drop of the extra 3V, a series resistor R = V/I = 3/0.02 = 150 ohm. The three leds should be connected in series with the resistor.
Three strings will allow nine leds and the current drain will be 3 * 20mA = 60mA

You can work out the resistor if you want to add the odd led.

10. ### sage2605

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Feb 9, 2013
all 10 white leds turn on together but I can cut that to 9 and just add the last one with its own resistor.the RGB leds (9) will all be on at the same time but different colors (no mixes,just basic RGB).The reds (16) will be on only when switched but all wil be on..thank you

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Feb 9, 2013
Thankyou