RE: LED rules of thumb

["Bricknell, Tony" <tony.bricknell@xxxxxxx>]

An easy solution would be to do this (time for bad ASCII art)

--------------------------- 12V
               
  -      -   
-    - 
           
R          
           
  -      -   
-    -
               
---    ---  ---  ---
\ /LED \ /  \ /  \ / etc, etc.
---    ---  ---  ---
               
---------------------------- 0V

Following this example, 20 LED's are going to draw 20mA each - total
current
demand from 12V supply = 20 * 0.02 = 0.4  Therefore make sure
wall-wart can
provide 400mA at 12V.

LED wants 20mA at 2.1V (again, all made-up figures - you'll need to
substitute your values from the  manufacturers data sheet)

R = V / I = 9.9 / 0.02 = 495 ohms (use nearest higher value, 560 ohms)

HTH
Tony


-----Original Message-----
From: Stu Worrall [mailto:stuart@xxxxxxx]
Sent: 17 September, 2002 14:55
To: ukha_d@xxxxxxx
Subject: RE: [ukha_d] LED rules of thumb


Complete electronics thicko here im afraid but what if I wanted to put
20 in a line to go down the garden?  Im assuming I will need a
resistor
for each LED and a 12V supply.  So the big question for me is do they
go
in parallel or series and can I get away with this many on one line?

Thanks

Stu Worrall

<snip>

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