BJT 100KHz Colpitts Oscillator Using 2N2222

Hello everyone,

I am trying to make a 100KHz Colpitts oscillator circuit using a 2N2222. I am not hung up on the frequency of oscillation or the Q-factor. I am doing this just for the learning purpose. I have looked at several websites and videos , but I did not find them helpful, most probably due to my knowledge shortcomings. So, I want to know how I should go about it? Any help will be appreciated.

I know these conditions for oscillation:

  1. Gain of bigger than 1
  2. Zero degrees phase change between the input and the output

Let me let you know what I have done so far. I made a common-emitter amplifier, also made a feed back circuit feeding back from the output, collector back into the input, base. Then, I feed a 100KHz sine signal into the base, and I look at the output, making sure that the two waveforms align, with the output having a bigger amplitude to it. Then, I disconnect the input, and turn on the amplifier, hoping to see the any kind of oscillation, but I do not see anything on the output. my guess is that eyeballing for zero phase change is not a good idea, but I do not know how else to go about it using an oscilloscope.

Any comments would be greatly appreciated. Thanks everyone in advance.

by tadeh89
December 13, 2019

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