Magic Oscillator

How is it possible to oscillate between 10 volts and 10 volts? Seems pretty constant to me @10v

You can see that as common base circuit while the emitter as input becomes its voltage from the collector. From Ice (current collector emitter) the emitter is the input of this harmonic oscillator.

Strangely enough, if the AC power supply is binned, the oscillator no longer works. That would appear to be symptomatic of a glitch to me.

Its not a glitch. The Q of the resonator is infinite, plus my explanation before it makes an oscillator

And if you have "banned" the dummy AC you have to go down on simspeed to 10ns/s

@DastardlyD: That's a rounding issue in the display of min and max volts.

@hurz: "Binned" = thrown into the rubbish bin. Possibly a British expression.

@eekee: Correct, common english term. @hurz: yes it does start to oscillate, very slow to build up, any ideas on how the dummy AC helps out.

@BillyT, hmmmm, if a dummy source is present, the simulator seems to work with a three times higher oversampling. This can only be answered by Igor.

@BillyT, hmmmm, if a dummy source is present, the simulator seems to work with a three times higher oversampling. This can only be answered by Igor.

If a dummy source is present, like for example, 1kHz, then it simulates as if it were running at 333uS/S, but can actually be run at 3mS/S, for 9 times oversampling. The same thing is happening with the 100MHz source.

Okok, thats fine. We noticed there is some oversampling which explains the difference in behaviour if AC source is present or not. But this was not the question.

Using current traces on the output components gives an interesting picture.

Umm... Unless im missing something, you have an lc osulating cirrcuit causing voltage flux, then the npn is used to bleed out voltage spikes, dependent on the voltage divider. Am i missing something? I am a bit if a beginner.

You probably are missing something. That something is the miller capacitance. Imagine a 5pF capacitor connected between the emitter and base, and another one connected between the collector and base. Those capacitors are the parasitic capacitance of the transistor. The miller capacitance should change with the voltage at the base, but this simulator doesn’t simulate that. The miller capacitance creates a feedback combined with the RC network at the bottom, and it’s own RC network (the miller capacitance combined with the voltage divider resistors) which creates a net effect of amplifying the oscillations.

Jason you missed something, the miller capacitance is not need here to start an oscillation

? Without miller capacitance, there is no feedback and thus no gain. I don’t understand.