I built this up to see how well the blue LEDs I got recently would work on the DC output of a JT. I put three pairs of two in series on a perf board and soldered them to the air wired JT. I knew that the Vf of two blue LEDs was going to
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Archive for the ‘Power supplies’ Category:
2013-03-05 1.5V to 9V DC-DC Converter For DMM
I built this 1.5V to 9V DC-DC converter. It’s a modified Tim Williams design. It’s a Joule Thief with the output rectified and filtered, which is compared to the “Vref” zener diode and if the output voltage is too high, it turns off the base bias current to the Q2 driver transistor. The input is
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2013-02-15 Cell Phone Charger, Auto Type
I drew this schematic almost ten years ago, and of course the actual charger is nowhere to be found. I think it may have burned out somehow, and that was why I drew the schematic. Whatever the case, it does have current limiting, which has to be in anything like this that might be used
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2012-12-23 Watson’s Massively Parallel Capacitor Array
I finished gluing the 10 000 uF capacitors down to a piece of wood. I now have a Massively Parallel Capacitor Array (MPCA) Now the hard part comes: connecting all 150 of them up in parallel. I bought a whole box of 250 electrolytic capacitors on tape and fan folded. They were only ten dollars
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2012-09-14 9V Battery Substitute
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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2012-09-01 Question Of The Month
Question Of The Month: Every duplex electrical outlet should come with a 5V USB charging port built into the outlet next to the sockets. [ ] I agree [ ] I disagree Well, I’m afraid that someone has already thought of that*. I was in the Big Box home improvement store this weekend and they’re
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2012-08-27 High Voltage Joule Thief Schematic
High Voltage Joule Thief Schematic – In this Youtube video, we see the circuit connected to and lighting a neon lamp. I corresponded with the author and he gave me permission to post the schematic to my blog. Here is the link (it’s a .PDF). High Voltage Joule Thief The author sent me some closeup
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2012-08-14 Broken Duracell Charger
Not long ago I bought a Duracell charger for my cell phone. It has various adapters to fit the different power connectors, in my case it was the Micro USB. I connected my cell phone to it last night and plugged it into the wall, and this morning I went to unplug it from the
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2012-07-29 V Converter, 1.5V to 9V
I found a Youtube video with a two transistor circuit (some mistakenly call this a Joule Thief) that is used a a voltage booster to give 9V from 1.5V or 3V. He shows the schematic of the circuit at the end. I had a similar circuit in my late great watonseblog. But I think
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2012-06-10 Peter’s Geiger Counter Questions
Peter emailed me with a question about Geiger Counters. With his permission, I’ll quote his questions in the paragraph below and answer them following. it´s Peter again – a few weeks ago I purchased a good, sensitive (and fully functional!!) Geigertube for measuring background radiation – the only problem is that it requires 1000 Volts.
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