https://web.archive.org/web/20130326223836/http://www.quantsuff.com/ https://web.archive.org/web/20130326223836im_/http://www.quantsuff.com/images/Boost%20Basic1.jpg  It uses a BC337 to power the light while a BC327 PNP transistor is used as a timing switch. The coil can be any value from 20uH to 500uH, and choose a capacitor with a value of 5-10pF per uH of inductance (e.g. 100pF to 200pF for a 20uH coil). A resistor of 100K will drive the LED at 20mA. Lowering the value of R will drive the LED with more current. With a high-gain BC337 (the BC337-40), this circuit will work for up to 80mA. https://web.archive.org/web/20130903075123/http://quantsuff.com:80/LED2.htm https://web.archive.org/web/20130903075123im_/http://quantsuff.com:80/images/SJTx2%2025mA-c.gif  The 2-transistor 1-cell boost circuit can also be 'supercharged' for increased output. The parts shown here will allow a 1.2v rechargeable cell to light a 25mA white LED, change R1 to 68k and the LED will run at its absolute maximum. Care must be given because the power is delivered as a sequence of pulses, some as high as 100mA, but averages to 25mA. As a result, the light will seem brighter and more blue to the eyes. The circuit will accept coils from a few uH to 3mH; C1 should be 5-10pF per uH of inductance, up to 0.05uF for 1mH and larger. In general, larger inductances will supply LESS current. R1 adjusts the brightness, and can be 22M-ohm down to 33K, which in this circuit will light 100mA and 1-watt LEDs. - 2N869 http://pdf.datasheetcatalog.com/datasheets/15/487156_DS.pdf - 2N869A http://www.datasheetspdf.com/pdf/1119783/Motorola/2N869A/1 - 2N4401 http://www.farnell.com/datasheets/661741.pdf