One of the earliest germanium transistors was the 2N404. It became a popular transistor for use in projects after the demand for germanium transistors fell when Texas Instruments and other companies started selling silicon transistors (for more transistor history see here). I recently bought some germanium transistors labeled 2N404, but they seem to have much
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I had these pics of my JTs from 2009, both conventional and supercharged JTs. The conventional JT is lucky if it can be 50 percent efficient. My Supercharged JT will do upwards of 80 percent easily, using much less battery current while giving the same amount of light output. I believe I have seen only
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I was reading a post from a school teacher about wanting a subject for the class project. Bingo, I thought of something that had not really come up before: “How much does it cost to make a Joule Thief?” I guess it would be best to start with a BOM, or Bill of Materials. The
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Another pic from the past – Apr 2009. The 10 Farad supercapacitor powers the flasher brightly for 1 hour and dims for another 3 hours. The circuit consists of an astable multivibrator with unequal resistors to make it put out a short pulse every second or so. This is the three transistors to the left
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The 2N2222 and 2N2222A comes in, and has always come in a metal can package. The manufacturers came out with an equivalent that was much cheaper because it does not have the metal package, it’s a regular TO-92 epoxy package. The 2N2222 and 2N2222A specifications require a metal can package, so the manufacturers named the
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These tiny T231212T toroids from Surplussales.com are high permeability so it doesn’t take much wire to make a good Joule Thief coil. The core is less than a quarter inch diameter (here is a data sheet in .PDF.). Six inches of 30 AWG magnet wire trifilar wound, with two of the windings connected in parallel
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It will work with a few hundred millivolts.DAMASCHKE-064a-97ia-jmd
This piece of oak serves as a quick way to swap parts for a Joule Thief. I have an air core coil connected to it, and a 3mm white LED which is tired from being used for a few hundred hours. The plus and minus wires are each wrapped around a steel screw and the
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Most people with some exposure to technology have heard of Moore’s Law. Well, I for one had never heard of Haitz’s Law. It is basically similar to Moore’s Law but applied to LEDs. I read the Wikipedia article in the above link and learned about not only Haitz’s Law, but that the luminous efficacy of
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Here’s a screenshot of my DSO with the scope probes across the LED. The pic on the bottom is the actual Joule Thief. The capacitor that is half hidden at the bottom is a 10 uF bypass capacitor.
