here is a simple yet quite effective switching mode voltage booster that you can use to drive LEDs with.

it utilizes two transistors, two resistors, one capacitor (optional) and one inductor. simple enough?

it takes one battery, working down to 1-1.1v, and boost the voltage up to 18-20v, depending on the transistors used. the circuit runs from 20-30k to several hundred khz, based on the parts used.

to92 devices are good up to 3 - 4 LEDs. above that, you want to use larger transistors, like BD or ME parts. Try not to use to220 or bigger parts as they cannot run fast.

you can use it to drive high brightness LEDs, without any problem.

enjoy.

 

the circuit outputs pulsed dc right now. with the addition of a diode and a capacitor, it can output stable dc.

this allows higher brightness with fewer LEDs.

 

Since there doesn't appear to be a question here I think that this belongs in the Projects Collection section.
http://forum.allaboutcircuits.com/forumdisplay.php?f=14

 

My solar garden lights use a similar circuit for their LEDs to glow dimly all night long in summer.