LED schematics
I went to led.linear1.org/led.wiz and was looking at the layout given to my specifications, and it was 15 LEDs, but im making an LED bar, and the schematics showed that i needed 120ohms resistors per 3 LEDs, but I dont want to have to run a line for 5 different segments, what type of resistor would I use for all 15 instead of one for each each 3. (would I just add 120X5 to get my answer, or does it not work that way?)
ill be using a 12v battery.
ill be using a 12v battery.
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- Stephen
I dont have any data on the LEDs I was able to scrap some off of some solar yard lights my parents had given me, (no labels) the solar lights used 1 AA battery (1.2v 400mAH rechargeable NiCd) with a circuit board, silicon diodes (2), a capacitor and thats it.
Post Edited (JR_301) : 6/22/2009 3:12:32 AM GMT
Post Edited (JR_301) : 6/22/2009 3:35:16 AM GMT
A regular red led might have a voltage drop of anywhere from 1.7 to 2.3 volts, for example. So if you put 5v in one side, you get 3.3v out the other. The resistor just limits the CURRENT so the LED doesn't burn out (and/or to limit the current being used by a microcontroller pin so it doesn't burn out).
So you can calculate current for a series string of LEDs easily enough, BUT you must also take into account voltage drop. If the drop is 1.7v, you can't power three LEDs from 3.3v (the total drop would be 5.1v, more than you started with). With 12v, you can perhaps do 4 or 5 LEDs.
This calculator may help:
www.theledlight.com/resistancecalculator.html
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When the going gets weird, the weird turn pro. -- HST
1uffakind.com/robots/povBitMapBuilder.php
1uffakind.com/robots/resistorLadder.php
WOW! that was a breath of fresh air, I was so confused on that, THANK YOU!