Verify screen grab of my VHF Series Resonator Oscillaor

[Xanax]

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!
http://homepage.eircom.net/~doylekevin/SeriesResonatorOsc.JPG


Cheers,
Kevin.

 

[Tim Wescott]

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!
http://homepage.eircom.net/~doylekevin/SeriesResonatorOsc.JPG

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.

 

[John Woodgate]

I read in sci.electronics.design that Xanax <[email protected]>

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!
htt

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.

 

[Scott Stephens]

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!
http://homepage.eircom.net/~doylekevin/SeriesResonatorOsc.JPG

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!
http://home.comcast.net/~scottxs/

POLITICS, n.
A strife of interests masquerading as a contest of principles.
The conduct of public affairs for private advantage. - Ambrose Bierce

**********************************

 

[Rich Grise]

Basically, it's oscillating so hard that one of the active devices (I
can't see the schematic clearly - why the black background?)

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

 

[Kevin]

Thanks people! I try to change it based on your suggestions!!

Cheers,
Kevin.

 

[Scott Stephens]

Thanks people! I try to change it based on your suggestions!!

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!
http://home.comcast.net/~scottxs/

POLITICS, n.
A strife of interests masquerading as a contest of principles.
The conduct of public affairs for private advantage. - Ambrose Bierce

**********************************