Voltage booster - need help with project please

I am new to electronics as a hobby, and I have really tried to get this to work (for weeks) without asking for help. But now I am at a standstill and would appreciate any help you may give.

What I want to do is take 1.2 - 1.5 V DC and boost to 4V+ DC and around 25-30mA and run an LED with approx 3.6 forward voltage drop.

I found a voltage boost circuit on the web (might have even been here). I have modified it somewhat and put it in a simulator (Switcher CAD) - it apparently should work, see the attached schematic and two graph plots from the 1.2v input. One plot shows the voltage going into the LED, and the other shows the current across the LED from the simulation.

Ok, so far so good. According to the simulation this should work. Sure, the LED will oscillate, but it should be too fast for humans to notice.

But, I built it on the breadboard and it does not work. On the breadboard, with 1.2v or 1.5v supply, I show very lom mV measure (like 30 mV) going into the LED with the DMM.

I have attached a picture of my breadboarded circuit also, with annotations of the components. Will someone please take a look at the attached schematic, graph plots, and breadboard pic and let me know what I have done wrong?

I think I have all the nodes correct on the breadboard, but I just can't make this work.

Any help will be appreciated.

Thanks!

I don't see why you're having a problem.

Have you checked the battery voltage and that all the connections are good?

Note that even though you might have pluged the right bits in the right holes and the correct way round, bread board has a nasty habit of not making very good connections. I'd check the connections between all the components with a multimeter.

There are other much simpler circuits that can power white LEDs from single AA cells.

**broken link removed**
http://www.joulethief.com/kit.php

Help - Thanks!

Thanks everyone for mentioning Joule Thief. That is what I needed!

Didn't I answer this on another website?
The voltage divider of R1, R4 and R3 assures that Q1 will never turn on.
The LED should go to ground instead of to the positive supply then the boost doesn't need to be so high.

I found this on my hard drive: