2011-04-18 2011 Apr 18 JT Transistor Switch … I thought that it would be a really great idea to put several transistors on a switch so that I could switch between transistors and compare their performance. I only have to connect the base and collector leads to the switch. The emitter lead is almost always
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Two years ago I decided that I wanted to get a light meter. I had two old light meters for setting a camera, one was a Weston and the other a G.E. Both were not sensitive enought to give an accurate reading of a LED. I had some other choices, one was to use a
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I got an email from QS showing how he put the buck DC-DC downconverter right at the point where it plugs into the proto board. This is really the way to go to eliminate any IR drops from the resistance of the leads. There are two items which I am concerned about, one being
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Well, it’s Friday the 13th. We just had a Friday the 13th just 13 weeks ago, and we will have another one in 13 weeks. Wow! That’s almost spooky! Friday really was Friday the 13th for me and my co-workers. We had several network problems, one which required me to run from one building to
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I got a link from Quantsuff, about making jewelry out of Nixie tubes. Bill ‘Botronics‘ Sherman replied that Nixie tubes need 140 to 170 volts at 2 milliamps. Meanwhile, I’ve got ten thousand or more of the Dionics DTN-205 transistors in my parts bins that were made for driving Nixies and VFDs. I liked Bill’s
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I made this and I used an old HP 721 power supply set at 31 volts to power the LEDs. The 8 LEDs on each side of the middle are in series and add up to about 25 volts. The two sides are then connected in parallel. The 721 PS is set for 30 mA
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This is a photo of an ancient Dressen Barnes power supply from the 1950s. It uses germanium transistors throughout. Some of them are located on the other side of the board, and the only thing that can be seen are the nuts holding them down and the two holes where the leads pass through. Some
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This is a picture of an almost dead white three chip LED. The white phosphor has mostly disappeared, leaving the blue LED chips showing through. This has thousands of hours on it, but nowhere near the 100,000 hours that they are claiming LEDs last. I have tested a few dozen white LEDs and all of
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In the world of Electronics, as in the Real World, there are those who try to manipulate the truth to take advantage of those who have a limited understanding of its underlying principles. We will call these manipulators scammers. One scam that I often see is when an experimenter tries to get a LED circuit
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I blogged this a long time ago, but my old blog is gone, so here it is again. I unsoldered a large number of these 600 ohm hybrid transformers from PBX boards. Each transformer has four 600 ohm windings, and is used to interface to the PSTN (telephone central office). Notice that there is a
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