LinkBack Thread Tools Search this Thread Display Modes
Prev Previous Post   Next Post Next
  #10   Report Post  
Old January 22nd 07, 12:54 PM posted to rec.radio.amateur.homebrew
external usenet poster
 
First recorded activity by RadioBanter: Jul 2006
Posts: 263
Default Bad Colpitts osc Waveform

amdx wrote:
On another note; I noticed the base waveform is pretty good. Has anyone
seen a design that
lightly couples a signal from the base to maybe a FET and buffers it. Just a
thought!


The collector waveform will always be much richer in harmonics than the
base waveform. If you want to multiply up this is Good. If you see some
random circuit in a handbook keep in mind that they may very well have
intended it to be used for multiplying up 2x, 3x, 4x, etc. so the bias
etc. may have been chosen just to make the waveform at the collector
look un-sine-ish!

There are numerous oscillators that take the output signal from a
tapped-down tank if they want a minimum of harmonic content. Tapping
down helps minimize the effect of loading on the tank Q, but taking the
signal from there will have at least some effect on oscillator
stability. Another place that might like look slightly nicer from a
waveform view (and may be lower impedance) is the emitter. And there
exists oscillators that put a smallish resistor in series with the tank
- the resistor value is chosen small to not degrade the tank Q very
much, and the small voltage across the resistor looks very sine-wavish.

Tim.



 
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules

Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Digital oscilloscopes for FM waveform capture? MRW Antenna 3 November 22nd 06 07:03 PM
WaveForm Generator [email protected] Homebrew 4 December 17th 04 10:05 PM
Extracting the 5th Harmonic Paul Burridge Homebrew 324 March 28th 04 10:34 PM
CW keying waveform ? Thierry Equipment 4 February 29th 04 12:17 PM
CW keying waveform ? Thierry Equipment 0 February 23rd 04 11:19 AM


All times are GMT +1. The time now is 12:33 AM.

Powered by vBulletin® Copyright ©2000 - 2025, Jelsoft Enterprises Ltd.
Copyright ©2004-2025 RadioBanter.
The comments are property of their posters.
 

About Us

"It's about Radio"

 

Copyright © 2017