This boost circuit implements current mode control and senses the LED current via resistor R14. The output voltage is boosted to just over 30V to drive 10 LEDs at a regulated current of 0.35A. Often, ...

However, a white LED presents a higher forward-voltage drop than do its colorful counterparts and thus poses problems for operation from a single 1.5V cell. The self-oscillating step-up converter in ...

I remember making a flasher with a LM3909 back in the late 1970s. It was very efficient. In regards to this circuit, I can think of one that is even simpler, although not so stable.

For under $20 you can get a LED tester (look for TV back light tester) that’ll test anything from IR LEDs @ 1.2v up to 300v. Not sure why so high when TV back lights are usually around 100v.

An LED Lamp That Pops Up From A Single Circuit Board. You’ve got to see pictures to appreciate the simple ingenuity behind this lamp, which took three years of research to make.