I bought some ‘high current’ chokes from Jameco, P/N 642855, which are 390 uH. They’re bigger than average, and mount axially; in other words the leads are at opposite ends of the cylindrical package. They are made by winding relatively heavy copper wire onto a ferrite bobbin. The bobbin is then covered by a piece
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I bought some Jameco inductors, among them was Jameco Part No. 371215, which was a closeout sale of $.49 each. Their picture shows it as uncovered wire, but all of the ones I got had a black heat shrink tubing around the circumference. The wire diameter was 24 mils, or about 23 AWG when the
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Using a resistor in series with the LED or supply The reason for using the 1 ohm current sensing resistor between the LED cathode and negative is that it has lower resistance than the meter. The meter’s internal resistance varies depending on the range setting so one can’t depend on getting consistent readings between ranges.
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Quantsuff sent me a link to a short video of a toroid being wound using the cheating method. The toroid is broken in half, the turns are wound on and the two halves glued back together. Quite some time ago I participated in a discussion about doing this or a similar method and I’m not
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I received an email from Paul, with some good questions about the Joule Thief, particularly about the coil. He’s given me permission to use them in this blog. Here is his intro and first question: Imagine 1st an average JT circuit just as frequently made. 1 transistor, 1 white LED, 1 resistor, 1 battery at
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I built this coil, modeled somewhat after the coil I saw in this Youtube video. It uses 24 AWG solid telephone wire, and the winding color indicates the number of the winding according to the resistor color code: 1 (brown) through 0 (black). The first and last windings are 5 turns each. The windings in
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I received a Google Alert for a Youtube video from Mongrel Shark showing Joule Thiefs with his version of Tesla’s Pancake coils. He refers to and gives the number of the patent Tesla had on this pancake coil (I haven’t read it yet). He used two coils, each with its own Joule Thief. For some
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I wanted to get some 100 microhenry chokes to experiment with, so I ordered a bunch from BG Micro. Also, I found they had some Steward 2B0686-100 EMI Suppression Filter, which once I cut through all the gobbledygook, came down to toroid cores. So I ordered a dozen or so of those. Then I found
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Well, I saw this way of emulating a coil in the Wikipedia entry for Joule Thief. I said to myself, this is really Mickey Mouse, and it would never withstand the scrutiny of an engineer or designer if they saw it. It’s just not the way a circuit should be designed. But I did it
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A picture of my Supercharged Joule Thiefs and some coils I wound. I noticed that the LED in the center has a big bubble in the lens. I got some LEDs with bubbles in them from a seller on eBay, and I had to send them back to get a refund. I think this must
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