Sloppy more or less always working 1 transistor oscillator that can work for HV etc. demo/schematic

Please read the description/textbox first. About this video: the most basic 1 transistor coil oscillator is showed (schematic/demo/practice), how it works and why it more or less always works.

Of course in electronics nothing is sure, but this setup of a coil/radio oscillator, also usable to make high voltages, has a high success ratio. That is why I show the principles, perhaps another demo will come.

Very important: reverse the electrodes of the output coil (the secondary coil) to the coupling capacitor (first idea 50 N-100, depends on the frequency) when it does not want to oscillate. Has to do with the right phase of the back coupled signal; it must be right to give oscillation. More info in the video.

And: also very important: use a transistor (or a Darlington) with a high current amplification.

More or less everything is told in the video:

* basic biasing via one resistor in the 47 K range
* better and more precise biasing, via that 22 K potentiometer and a protective resistor to limit the base current to a safe value for the transistor or the Darlington
* the phase issue (reversing a-b electrodes of the secondary coil, necessary for oscillation)
* something about the frequency that you can expect (depending on the coil inductance, don’t worry, this circuit almost always works)
* the supply voltage where it can work; with no resistor in the emitter lead even on 0,75 – 0,8 Volt, when you use a (NPN) transistor with a Hfe of say 300 etc.
*when you use a Darlington (say 2 x BD 139 or 1 x BD139 and a 2N3055), the bias resistor (to the base of the Driver transistor, that is the first transistor in the Darlington) must be in the 100 K-1M range.

Corrections to the video: on 3.03 I say that “the core is going into oscillation”, but of course I mean the coil (combined with the e.m. properties of the core) gets into oscillation.

On 10.22 I talk about a more precise biasing of the oscillation transistor, via that 22 K potentiometer.

In such cases you can get a much better waveform (say a pure sinus) on higher voltages (=everything higher than 1 Volt, normal voltages, say 9-12 Volt) when you mount a resistor in the 27 Ohm to 100 Ohm range in the emitter lead of the transistor. Bridge it with a capacitor between 220 pF and 1 NF (=1000 pF) to take out the purest sine wave.

Study all these things via an oscilloscope to get the best results. And very important: experiment with bridging the primary coil with a capacitor (1N-100N). It helps/can help the oscillation + gives better sine wave like waveforms.

Experiment! Study everything with the oscilloscope.

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I keep all my YT videos constant actual, so the original video’s with the most recent information are always on YouTube. Search there, and avoid my circuits that are republished, re-arranged, re-edited on other websites, giving not probable re-wiring, etc. Some persons try to find gold via my circuits. I take distance from all these fake claims. I cannot help that these things happen. Upload 6 june 2022.