A friend of mine has taken on the task of finding replacement AC adapters for two laptops, and I thought that I could repair the broken cord on one. But I tried to take the brick apart and damaged it beyond economical repair, so I resorted to the ‘Net to find replacements. He gave me
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Kirk has given me permission to use his picture in this blog. He builds them on Arborite, which is similar to Formica. It looks a lot nicer than the cheap plastic I’ve used. He says: Bottom left is a float charger, top left is a cut out relay circuit, the middle is a battery desulfator,
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Well, the LEDs I ordered more than a month ago have finally arrived. They are 10 Watt(!) 900 lumens from Electronic Goldmine for $6 (USD) apiece (I checked their website and they seem to be sold out). The reason why it took so long was mostly my fault. They were shipped to my previous address,
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Danny left a comment about powering a 12V, 3 Amp LED light with super capacitors. He asked for my thoughts on this. I’ve made higher power Joule Thiefs and I’ve tried to power several things with super capacitors and although my experience with this isn’t as extensive as my experience with JTs, I think I
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When I work on a Joule Thief I need a power supply that will go all the way down to zero volts. Kirk pointed me to a high current power supply (6 to 8 amp) that puts out zero to 30V and uses a LM317. I have built a power supply that uses a LM317
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There seem to be a zillion pitfalls out there just waiting to entrap the unwary buyer. Take for instance my dilemma. The bozo at work borrowed the Brother P-Touch labeler and brought it back without the AC adapter – apparently he lost it. So we put eight AA cells in the battery holder and it
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In an email, Kirk said that he has found that ‘dead’ laptop batteries often have only a single cell that’s bad. I have torn apart some Dell laptop batteries, and found that they have a PC board that has some kind of battery management capability. I also found that the five or six cells
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I had a Joule Thief already assembled, using point-to-point wiring. The transistor was a BC338. The coil was a 3/8″ (9mm) toroid core with a primary winding of about 20 turns of 26 AWG and 666 uH, and a feedback winding of 190 uH. The resistor was 1000 ohms. Modifications I disconnected the feedback (base)
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I originated this in SwitcherCAD III back inApril of 2004, and posted it to my late watsonseblog. The one on the right seems to be more commonly used.
This is the second one I’ve built. The first one I built is in my earlier blog – links to the schematic can be found there. I used the following parts: a 2N3906 for Q1, and PN2222A for both Q2 and Q3. R1 was 470 ohms, R2 was 10k and R3 was 8.2k. Both the
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