Colpitts Oscillator - not working

139

02:46:49

Why doesn't this appear to be working?  

This should be a copy of the "Practical Example" in the Wikipedia article.

https://en.m.wikipedia.org/wiki/Colpitts_oscillator (Overview fig.3)

published 10 years ago

jason9

10 years ago

Three problems: 1: the LED is a very bad idea that may the oscillator from working, and it will not work at the 50MHz of the colpitts oscillator. 2: in between the two caps there's a wire which you need to connect to the terminal of the transistor with the arrow. 3: when you press the clock button a knob will show up and you will need to turn it counter-clockwise until it says 100nS/S before you start the simulation. Hope this helps. :)

jason9

10 years ago

Fix: the LED is a very bad idea that may -stop- the oscillator from working etc.

jason9

10 years ago

Oh, and the circuit isn't properly grounded. That's another reason it doesn't work.

jason9

10 years ago

Actually, you can't do step three without starting the sim. So, start the sim, do step three, stop the sim, start the sim, and watch it work. It's important that after you do step three you stop then start the sim. Otherwise the oscilloscope won't work properly.

escriblings

10 years ago

1). Removed LED. 2). Added wire (can't believe I missed that). 3). Adjusted simulation speed, stopped and started, still didn't already to be working. Thoughts?

escriblings

10 years ago

Not properly grounded??? Where should the grounds be placed?

Tigozawr

10 years ago

Just make the capacitance of the EC cap different for a sec and then make it right again

hurz

10 years ago

and shake to start http://everycircuit.com/circuit/4800469210234880

escriblings

10 years ago

OK didn't know about the shake thing - strange. I noticed the adjust and adjust back, that's odd too. - what's bugging me now is that with all the values power the Wiki it's supposed to have a frequency of ~50MHz, and its not happening.

jacyhenry

10 years ago

There is nothing wrong with your circuit. I have use very similar circuits in real life and have a lot of success with them. I believe that it is the transistor model in this program that is the problem.

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