Hi,
I need to have a regular LED (doesn't need to be anything special like a superbright LED) stay lit as long as possible on either a single D cell or two D cells. D cells are rated for about 20.5A if used down to 0.8V. I'm assuming I would need some sort of regulator to do this... I think a regular LED is 20ma forward voltage 1.9v ?...
Thanks,
SA Dev
You are corect in the forward voltage assumption. Note, however, that different colours have different forward voltages. Most green, red and yellow (amber) LEDs are in the range of 1.6-2V when fully on. If you don't need much current (you don't), you could use a switched capacitor boost driver, or even a flying capacitor device. These things are all over the place - look at Maxim
Cheers PeteS
"SA Development" wrote
You will need two, not one, cell.
Experiment with values of series resistor, and choose the highest value which will give you an acceptable light intensity.
This can be done with one cell if a switched capacitor boost regulator is used. One might even use a low power/low voltage RS232 converter from maxim (output typically +/-5V).
Cheers
PeteS
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