There is a video on Youtube in which the vlogger who calls himself Chilliqueen(some number) calls a two transistor circuit a Super Joule Thief. I don’t agree, a conventional Joule Thief circuit has only a single transistor. Then he claims that the capacitor and inductor is “an RLC resonant circuit”. I again disagree. The capacitor does not resonate with the inductor. The capacitor blocks the DC and couples the AC back to the input to keep the circuit oscillating. Even if the capacitor, resistor and inductor were not connected to anything, the 100k resistor would be so much greater than the reactances of the inductor and capacitor that it would be difficult if not impossible to tell what its resonant frequency was. Connecting these in the circuit loads down the inductor and it can’t be resonating with anything. Its job in a Joule Thief is to store and release energy; it does the same thing here.
He goes on to say that the circuit will work from “20 microhenrys to 1000 microhenrys.” Then he demonstrates that it will work “with one turn.” A single turn of wire is a lot less than 20 microhenrys; actually I measured it at about 100 times less.
There are other suspicious things about the circuit. The resistor doesn’t look like a 100k resistor. Why are there holes in the paper, where the wires go through and connect somewhere else underneath? Is he trying to hide something from us? I have also seen other of his videos with similar errors.
In another of his videos, he claims that an oscillator made up of a transistor uses the “Esaki Effect” or tunnel diode effect. The Esaki or Tunnel Diode (you can read about its operation in this Wikipedia article) is forward biased and oscillates at a fraction of a volt; his transistor is reverse biased and must have 10 or more volts to operate. The transistor is operating in breakdown mode much like a Zener diode works. It is definitely not a tunnel diode.
In another video, he tells how to use two diodes and two capacitors to make a “charge pump”. The schematic he shows is simply a voltage doubler, not a charge pump. A charge pump uses switched capacitors to multiply the voltage.
All together, I believe the information he has presented was misinformation and he really doesn’t know what he is talking about.
Update Jan 9, 2012 I saw another video by this guy. He made a LED blinker using a 555 chip, without any resistors. Other people commented and pointed out that the LED had no current limiting resistor and could burn out. Also, the speed of the capacitor charge and discharge is determined by the leakage of the chip itself, and this would be unpredictable and unstable. I pointed out that this won’t work with a CMOS 555 because they don’t have leakage. This guy has again proven that he really doesn’t know what he is doing. I also dislike that he is misleading other experimenters into thinking that the circuit will work properly, when it was never meant to be used in this manner and will likely not work.