I bought a Joule Thief at the store today. Well actually there’s more to it than just that. Yesterday I stopped by Harbor Freight and bought a heat gun (that’s another story) and I saw something that caught my interest. It was a battery tester for $2.50 that had three LEDs. It tested two kinds
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I was observing this video, and I saw that the 2N3904’s collector was connected to the negative and LED cathode, and the emitter was connected to the coil winding and LED anode. But I was surprised that when he connected it up, the LED lit up. Weird. But when he tried it with the 2n2222A
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I received a Google Alert with a link to this Instructable. The author uses the two transistor, single winding voltage booster, often incorrectly called a Joule Thief, because he wanted to avoid having to wind the two winding coil. The Joule Thief name was given to the single transistor, single resistor, two winding coil version.
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A few years ago I made a LED tester that used a 9V wall wart, a 5V zener for a shunt regulator, and three 100 ohm resistors to limit the LED current – one resistor for each LED socket. The problem with this was that it was plugged in all the time and since it
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Here is my latest germanium Joule Thief, shown squeezing the last few hundred millivolts out of the Energizer Bunny (“It just keep going and going…”). This is a real Zombie Battery Killer – that last half volt left after the regular silicon JT has given up is now sucked out, down to less than0.2V.
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In an earlier blog a commenter asked asked a question about how much inductance a Joule Thief should have; is there too much or too little. Well, I assembled and experimented with this Joule Thief to find out how little was too little. I cut of two 16 inch (40 cm) lengths of 30 AWG
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The photo is of one of my Supercharged Joule Thief circuits that I built a few years ago (see link at the end). This one has a supply current of 70 mA at 1.5V and a LED current of 25 mA at 3.3V (actually 25 millivolts measured across the 1 ohm [2 resistors] in series
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I found this picture of a Joule Thief on this forum, but it requires login, so I’m going to post it here. This sure won’t take a prize for beauty, to put it mildly, but if it works, that’s what counts. I’m wondering how that coil can work with all those weird wires around it.
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Reasons to not use a 2N3904 in a Joule Thief or other high current circuit I’ve said this more than just a few times before: when used in a Joule Thief circuit, the 2N3904 is pushed beyond its ratings and gives below standard performance. The maximum ratings for the 2N3904 are 200 milliamps collector current,
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I did this a few years ago and blogged it in my watsonseblog, now gone for more than a year. I guess it’s about time I did it again. The circuit is the two transistor circuit with a 2SD639 high current transistor for the output – it’s the same circuit I used in the flashlight
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