30th April 2008 04:24 PM
AVR Micro running off a Joule Thief!
Last night, I was messing around with a Joule Thief, and wanted to get a flashing-type LED to work. The joule thief produces AC, around 100 kHz (if I measured correctly, so a little noisey. Most of what I tried, would stop the oscillation.
Anyway, I replaced the LED with a 1N914 (still got about a thousand of them after almost 5 years...), put another from the positive side to the positive of a 10 uf capacitor, negative of the capacitor to the common ground. Put the flashing LED in parallel with the capacitor, and it flashed. Replaced the LED with an RGB fader board I had handy, but on the red lit up. Scrounged up a simulated flame board, work perfectly. Still going, about 12 hours later, off a rechargeable AA, which I took out of my camera to be recharged. So, pretty excited. Will try a freshly charged battery, and see if I can get the RGB to work, but suspect I'm loosing too much across the 1N914s or maybe the 78L05 on the micro board. Least I know the joule thief can do more then just light an LED. Also means, I can modify some solar yard lights that were too noisey to run a micro off...
That is a very good idea, but the voltage drop over that diode is only 1V spesefied in the datasheet.Try useing a 5V zenner as the diode but thurned the wrong way around.Or if you dont have one handy just use 5 of those diodes in series
2nd May 2008 09:54 PM
Have no idea where I put my zenners, almost never use them. Will keep it mind, I have to find some parts for a couple of other projects.
I found that a diode across the emitter and collector wasn't needed. Used just one off the collector to the positive side of the capacitor. Pulled the Attiny13 off its board, and used it without the regulator. With a freshly charged AA, got all three colors, but the blue didn't last for long. The red and green are still going, two days later... I've got some RGB LEDs, with the built in flash/fade, but need to hunt for them. It's still good that I can get the AVR to run though.
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