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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This circuit is connected across the phone line, and the pushbutton switch is placed close to the phone. When the pushbutton is pressed, the red LED lights up. The circuit is polarity sensitive so if the LED does not light, then the connections may have to be reversed. Once the LED is lit, the phone
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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 liked this story about the Rockwell 63R calculator – it’s about 2/3rds of the way down on this web page. I still have the one I bought with the help of a Rockwell employee who got me a very good discount. I also have another one that I picked up later. I used mine
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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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DMMs All Over The Place – I have more than a half dozen of those cheapo Cen-Tech DMMs from Harbor Freight laying around my house, and I use them a lot for checking the AA and AAA cells that I’m constantly trying to drain with my germanium Joule Thiefs with their multicolored LEDs, of which
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I was discussing with Aki (theledart.com) his JT blinker, which uses a single winding coil, two transistors for the “JT” V booster, and two transistors in an astable multivibrator to blink the “JT”. He asked me to include the schematic. The first circuit boards that I had made from ExpressPCB.com used an astable multivibrator. I
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A few years ago I saw a video on Youtube for a car wheel light that displayed a message as the wheel rotated. I have seen this same method used on LED lights for bicycle wheels. It was a row of LEDs that were synchronized to the rotation, and as the wheel rotated a
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