One Joule Thief I have not built (at least not in the same JT) is the low power JT with the CdS photocell. Almost all of my JTs with daylight shutoff used a LED as a light sensing diode, and then most were flashers. I have a bunch of CdS photocells but I haven’t really
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Paul discussed buying LEDs and I decided to write about some of my experiences with buying LEDs in this blog. I bought some LED assortments from an eBay seller, I think he’s from Canada. He’s still selling stuff. Most of the LEDs had bubbles in them. I dealt with him through email, and I said
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I went to my computer club meeting this Sunday and they had a really good deal on the consignment table that I just couldn’t pass up: three 21 LED panels for five bucks apiece. They’re built very sturdy, with a body of extruded aluminum and screws holding the end covers in place. The ‘handles’ on
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The LED flashlights I bought in March from Amazon (but shipped from Hong Kong) arrived recently and I’ve had a chance to use them a bit. I paid $5.49 apiece, with free shipping, but I see that the price (as of June 8) has gone down to $4.30, These have a Cree Q5 emitter, and
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This is an old schematic that I drew in Apr of 2005 using SwitcherCAD III (now LTspice). It is taken from the board I built and put in service for several years as a LED test jig for testing the lifetimes of various white LEDs. Needless to say, most of the white LEDs lasted less
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This is from the 1980s, it’s all red LED segments or dots. I tried to find an angle where the ceiling light would not show, but because it’s a bubble lens, just about any angle had that white reflection. The specifications are available on the ‘net. The box outlined in red is one of the
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Paul emailed and said he has built his 12th Joule Thief. Man, this guy is Helen Wheels – an even dozen in a matter of a fortnight (or week or two, I forget which). I’ve been puttering with the TE Flashers. I made most of them on small pieces of “Woodsie” wood that I got
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I found this LED website in Germany, I like it because it’s LEDs, LEDs, and more LEDs, and not an electronics parts distributor. The LEDs are broken down into various types, standard, high power, etc., etc., etc. I’m looking for a similar website of a store in the U.S. I figure it would be best
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I have built several of the “Single Cell Flasher With Two Year Battery Life” flashers found at Pigeonsnest.co.uk and they flash for what seems like eternity – they’re real misers when it comes to battery current. But the flash is somewhat anemic and I had never tried this type flasher with any color LED other
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If you open up a cheapo 9 LED flashlight you will find that they put 9 LEDs all on the same PC board and they are all connected in parallel. How do they do this without having the LEDs burn out? For decades, the engineers have warned us that you should never connect LEDs in
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