I got some SMT power inductors from dipmicro.com because I read that they were only 0.18 ohm and could handle almost 2 amps. The winding is on a ferrite bobbin and that is covered by a ferrite sleeve to give it a better magnetic path. But there is still an air gap between the bobbin
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I had no problems getting the 2SK170 JFETs from Futurlec. They were on tape. I don’t know what manufacturer, but they are not Toshiba. Right now, I think a lot of the major semi makers are abandoning through hole parts, and going to surface mount only. To get a through hole part, one may have
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My first ULVJT which used four JFETs in parallel was a success in that it put out light at supply voltages as low as 34 millivolts. But it put out only a minuscule amount of light, and needed to be increased. The next one I built had six 2SK170 JFETs in parallel. It used a
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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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I’ve been interested in very low voltage converters for quite a while. I blogged this document several years ago in my late great watsonseblog. Almost a month ago I was commenting on a circuit, often called a Joule Thief, that was powered at 27 millivolts by a Peltier junction and the heat from a guy’s
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I was watching a Youtube video of Xee2vid’s no toroid Joule Thief 4, which is a conventional JT that uses a Radio Shack 273-1380 audio output transformer (Xee2 doesn’t allow comments). The ad doesn’t say what the specs are but IIRC, it’s a 1000 ohm center tapped primary and an 8 ohm secondary. The small
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The typical JT coil is wound bifilar, two windings at the same time. Winding the wire at the same time makes it easier, and it’s electrically the same as if two separate windings were wound. I often use 24 AWG wire and wind the coil bifilar. But I also wind it using four pieces of
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I have built a number of the two transistor “Joule Thief type” V boost circuits, and they work okay. I am comparing the two typical types: the PNP – NPN and the NPN – NPN types. The common one is the PNP – NPN type which uses a PNP transistor for the first transistor and
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I built this up – tack soldered it together – before I drew the schematic. My intention was to make a circuit that was very low on power when the light deactivated it, and to use parts that the neophyte experimenter would already have. I wasn’t concerned about complexity or cost, but the three extra
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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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