Author Topic: led calculations  (Read 800 times)

Offline atomicareprise

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led calculations
« on: June 18, 2009, 02:22:44 AM »
i use this link http://ledcalc.com/

supply voltage:i did the direct contacts in the speaker so i'm supposing 3.6v..
                      5v if i use lm386...is this correct

voltage drop across led: 3.3(blue)

desired led current: 20mA...is this correct

how many leds: 12

18 ohms is what comes out...

just need your opinion guys if i'm heading on the right track...
« Last Edit: June 18, 2009, 03:51:35 AM by atomicareprise »
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Offline Max_Kreeger

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Re: led calculations
« Reply #1 on: June 18, 2009, 02:42:19 AM »
Or you could use this formula V=I.R

V= Volts
I = Current (amps)
R =  Resist (Ohms)

So e.g.:

3.6= 20.R
R= 3.6/20
R= .18

So yeah looks right. I'm just not sure about the desired led current.
Sorry.
« Last Edit: June 18, 2009, 02:47:08 AM by Max_Kreeger »

 

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