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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I was watching JonnyDavro’s Joule Thief driving a power transformer, which is used in reverse to step up the voltage to drive a CFL tube. He shows the schematic, and later says that the unlabeled transistor is a BD139. I added a comment, saying “What amazes me is that you’re getting these high voltages at
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The first thing that comes to mind when the experimenter wants to find out how much current is flowing through the LED is to measure it with a DMM set to read milliamps. This works okay if the LED is connected in series with a current limiting resistor. The DMM will add maybe 10 ohms
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Most silicon transistors have an emitter to base reverse voltage rated at 5 volts maximum, with some transistors rated as high as 6 volts. Old germanium transistors were higher than this, but when the manufacturers began to make silicon transistors, they apparently gave up having a higher emitter to base reverse breakdown voltage so they
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I received a message asking several questions about the Joule Thief. The asker asked to be explained in layman’s terms, so I’ll try to keep it understandable. First off, I do not use a Spice program to simulate the circuit. I used LTSpice a few years ago, but not any more. Why should I when
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I often read where people add the rectifier and filter capacitor between the coil/transistor and the LED. They claim that it increases the efficiency. I just want to clarify what I see is happening as the Joule Thief is operating. My observations are based on what I see on an oscilloscope connected to the JT,
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Joule Thief Special There are thousands of different types of transistors, made by hundreds of manufacturers. But it takes a special kind of transistor to give good performance in a Joule Thief. The transistor should have high current gain at high currents and very low collector voltages. A maximum collector current of 500 milliamps
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My watsonseblog dated 2007 Jul 14 Back in the early days of electronics, they would assemble several neon lamps with 1 meg resistors and 1 uf caps in a box, along with a 90V B battery. The lamps would flash in random patterns. These were called a “Do Nothing Box”. I guess this is
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Happy New Year! My watsonseblog dated 2009 Jan 1 Joule Thief, FET Only is the topic. In April 2005 I built a Joule Thief (circuit is in my blog and at the bottom of this webpage) that used both a 2N3904 BJT and a 2N7000 MOSFET, with the 2N3904 starting the circuit and the 2N7000
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My watsonseblog dated 2009 Feb 19 These may be dupes or unfinished. 2009-02-19 Joule Thief, High Efficiency, #01 Supercharged See the schematic and original blog here. I have built several of these high efficiency ‘supercharged’ Joule Thiefs (SJTs) to try to optimize the parts values, especially the coil. I’m posting these SJT blogs to allow
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