S
Spehro Pefhany
I need to project the beam a considerable distance. Hence the
high peak current. It's also why I want to have the option of
increasing the peak current above 250mA. Most 5mm IR LEDs I've
seen are rated for 1A peak, 100mA continuous.
Well, possibly the most elegant circuit would be a CMOS 555 driving a
P-channel MOSFET gate directly, assuming a reasonable supply voltage
so as not to be too close to the maximum Vgs.
Eg. http://www.diodes.com/datasheets/ds31125.pdf
http://www.nxp.com/documents/data_sheet/ICM7555.pdf
Total cost about 30 cents in 1K, even from Digikey, and it could
switch as much as a couple of amperes with 20% duty cycle, and the 555
won't need any extra bits to get 20% on-time.
Of course if it's a school project you may have to use the parts in
the parts crib, eh?