Colpitts Oscillator

197

04:39:55

Colpitts Oscillator sourced from Wikipedia at en.wikipedia.org/wiki/Electronic_oscillator

Copied circuit into EveryCircuit but it will not oscillate.

Any hints on what im missing?

published 7 years ago

hurz

7 years ago

Your link does show a "A popular op-amp relaxation oscillator." Nothing about Colpitts. Anyway, Colpitts oscillators easily run within everycircuit

hurz

7 years ago

Check this http://everycircuit.com/circuit/5439082254827520

Stiofan

7 years ago

Thanks very much for your input hurz, I appreciate you taking your time to reply. The link has my colpitts example under harmonic oscillators beside a Hartley oscillator example. The figures I got from an example on the Colpitts Oscillator entry also on wikipedia

Stiofan

7 years ago

If I'm reading your example correctly, my figures were off by a factor of 1x10^3?

hurz

7 years ago

Right, only the choke coil was wrong, beside the simulator setup which must be much slower. Keep it up!

Stiofan

7 years ago

Thanks again hurz

Stiofan

7 years ago

I have changed the figures to match your circuit hurz, still no oscillations though.

hurz

7 years ago

You missed the point simulation speed. Set it to 10ns/s and it does oscillated

Stiofan

7 years ago

Lol my scaling seems to be way off, I had lowered the time scale from 5s to 1ms and was still 1x10^6 too fast. Is that due to the MHz frequency range?

hurz

7 years ago

Its oscillating at 67.4MHz, which is a periode of 14.8ns. To have at least two calculations within this periode of time everycircuit needs a simspeed of 148ns/s!!! But this is only for two lousy points in time. Set simspeed to 10ns/s gives something of every 500ps/s a sample to calculate and comes close to what it is in reality.

Stiofan

7 years ago

Ok, thanks. I think i have misunderstood the chokes role in the system

Stiofan

7 years ago

Im trying to design, build and test a wireless low power transmission device, for personal/educational purposes, I have an old cell phone receiver unit to test it. Would you advise i use diodes to protect against spikes from the inductors?

hurz

7 years ago

Good colpitts oscillators do not have spikes at inductors. Its not a joule thief, which is working in switched mode. Colpitts oscillators are so called harmonic oscillators were only a little amount of energy suppose to be overtone energy. But as low as possible.

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