On 4/4/2010 Jim Brown wrote:
> Studying the schematic showed that the existing bulb is driven from
> regulated 12VDC. On my workbench, I tried 5 LEDs in series on my
> regulated and current limited HP supply. That wasn't enough to
> overcome their barrier voltage, so I dropped down to 4 bulbs. That's
> quite nice, draws less than 5 mA from 12V, and puts out a lot of
> light.
IF you are dealing with a variable voltage (unregulated) power source, and want
to feed an LED (which are current devices), you can use an LM-117
http://cache.national.com/ds/LM/LM117.pdf
scroll down to page 18 or so, where there is an example of a 1A constant
current regulator - if you change R1 to say 62 Ohms (nominal), you'll have a
20ma constant current source, which is right for most LEDS, and you won't fry
them as voltage changes
--
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pursuing invariably the same Object evinces
a design to reduce them under absolute Despotism,
it is their right, it is their duty, to throw off such Government,
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