I'm not a terrific oscillator expert, but: your oscillator is squegging. This happens when there are two resonant frequency in your network where there is gain. I suspect that the ratio between C1 and the series combination of C2 & C3 is too extreme.
-- Tim Wescott Wescott Design Services
Trying to build a super-regen receiver? Move the junction of R1-R3 to V1-R2, and lose R3 & C4.
Scott
-- ********************************** DIY Piezo-Gyro, PCB Drill Bot & More Soon!
It looks like the OrCAD SDT I had, except I had II, with no simulator. I used to take these same screencaps, load them into Paint Shop Pro and do a negative image. The background turns white and the red lines turn cyan. Then it was easy to edit 4 or so pallette entries and have proper black-on-white.
Cheers! Rich
Hi all, Please look at the screen grab I made below of a circuit simulation in MultiSim2000. Its a series resonator oscillator hooked up to a scope. The Oscillator takes about 3 mins to start up but I was wondering if the output should look like this. I thought I would generate a clean VHF signal (50Mhz) with a constant amplitude.
Any ideas or thoughts welcome!
Cheers, Kevin.
I read in sci.electronics.design that Xanax wrote (in ) about 'Verify screen grab of my VHF Series Resonator Oscillaor', on Fri, 25 Mar 2005:
What a BEAUTIFUL squeg! I bet you could try a dozen oscillator circuits and not get another as classic as that.
Basically, it's oscillating so hard that one of the active devices (I can't see the schematic clearly - why the black background?) is being biassed off, which cause the oscillation to die away. The bias then collapses and the oscillation starts again.
-- Regards, John Woodgate, OOO - Own Opinions Only. There are two sides to every question, except
It may still not work. Try changing R2 to 10 or 100 ohms & put a .1uF at the collector to ground. And put an RF choke or resistor of 1K between the emitter and ground. Then it will look like a typical series-tuned Colpitts or Clap oscillator.
Scott
-- ********************************** DIY Piezo-Gyro, PCB Drill Bot & More Soon!
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