Forrest W Christian email (remove spam text)
I seem to quite often need to run a "voltage present" LED on a very wide
range of voltages... For instance, in one case the input voltage can
run from 5 to 60VDC, or more.
I need to power this LED from the power source, but need to regulate the
current so that the LED is pretty much constant output across the
I'm aware of the standard schematic using a PNP, a Zener, and a couple
of resistors, but would prefer something with lower part count.
I'm also aware of the LM317HV, but the cost there is prohibitive (I
would need the HV becuase of the higher voltage range input).
Of course there's always the option of putting a regular voltage
regulator and resistor in, but again, that gets somewhat costly.
I'm hoping I can find something just marginally more expensive than
putting a current limiting resistor in place. Is there some magic
circuit I've missed...
See also: www.piclist.com/techref/displays.htm?key=led
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