Peter asked a question about why is there a need for two separate power supplies for the same project. I guess it never occurred to me to explain this simply, so everyone can understand it. I have often had to use a separate power supply for one part of a circuit, with a second supply
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There are many circuits that are used infrequently that are powered by the usual 9 volt battery. One of these happens to be a field strength meter (FSM), which is used for detecting the power output of a transmitter such as the one a radio amateur uses. Some FSMs are very simple and use no
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I needed to pick some grapefruit from the tree, and I borrowed the picker pole from a friend. I put it in my Civic and got home, took it out and picked some ruby red grapefruit. Man, were they Delicious! So Monday I got in the car, and CLICK! It wouldn’t start. Then I noticed
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I saw a few items at DX.com that look like they could be very useful. A USB power meter, with even more information in the display, compared to the somewhat lame Practical Power meter. You won’t be caught with a dying cell phone battery with this. It’s a useful addition to your flashlight collection. This
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Earlier this year I bought a cheap cell phone charger for plugging into the car’s cigarette lighter socket. It works, but it’s s-l-o-w. I can drive for a half hour with the cell phone plugged in and it says it’s charging but it only charges a few percent. As a result, I don’t use the
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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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