Low-distortion Audio-range Oscillator - Page 185 - diyAudio
Go Back   Home > Forums > Design & Build > Equipment & Tools

Equipment & Tools From test equipment to hand tools

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 12th March 2013, 03:39 AM   #1841
davada is offline davada  Canada
diyAudio Member
 
Join Date: Jul 2004
Location: Fort St John, BC Canada
Quote:
Originally Posted by RNMarsh View Post
No I have not. Took a detour at the 725D exit off ramp. .
Are you making any headway with that one?
__________________
David.
  Reply With Quote
Old 12th March 2013, 04:38 AM   #1842
RNMarsh is offline RNMarsh  United States
diyAudio Member
 
RNMarsh's Avatar
 
Join Date: May 2012
Location: 2457 Cascade Trail; Cool, CA. 95614
Quote:
Originally Posted by davada View Post
Are you making any headway with that one?
It too has potential because of the older opamps used in many places. But need schematic to know what and where everything of interest might be. I have had no luck in finding a service manual for it. So I have that project on hold until I get a service manual.

_RNM
  Reply With Quote
Old 12th March 2013, 09:54 AM   #1843
RNMarsh is offline RNMarsh  United States
diyAudio Member
 
RNMarsh's Avatar
 
Join Date: May 2012
Location: 2457 Cascade Trail; Cool, CA. 95614
Default A-P opamp?

Quote:
Originally Posted by dimitri View Post
Richard, they specify THD+N in 22kHz bandwidth:
Analog generator residual THD+N At 1 kHz _(0.00025% + 1.0 μV) [–112 dB], 22 kHz BW
Analog analyzer Residual THD+N: At 1 kHz _(0.00025% + 1.0 μV) [–112 dB], 22 kHz BW
Dimitri --- what opamp is used in the A-Precision's oscillator?

Thx - RNMarsh
  Reply With Quote
Old 12th March 2013, 11:41 AM   #1844
dimitri is offline dimitri  United States
diyAudio Member
 
dimitri's Avatar
 
Join Date: Oct 2002
Location: retired
Send a message via ICQ to dimitri
AD797
  Reply With Quote
Old 12th March 2013, 10:17 PM   #1845
RNMarsh is offline RNMarsh  United States
diyAudio Member
 
RNMarsh's Avatar
 
Join Date: May 2012
Location: 2457 Cascade Trail; Cool, CA. 95614
Any tricks/recommendations to using it to full advantage in oscillator app?

Thx-RNMarsh

Last edited by RNMarsh; 12th March 2013 at 10:19 PM. Reason: AD797
  Reply With Quote
Old 12th March 2013, 11:35 PM   #1846
RNMarsh is offline RNMarsh  United States
diyAudio Member
 
RNMarsh's Avatar
 
Join Date: May 2012
Location: 2457 Cascade Trail; Cool, CA. 95614
I mean beyond the literature and good practices. -RNM
  Reply With Quote
Old 13th March 2013, 07:34 AM   #1847
diyAudio Member
 
Join Date: Jun 2005
Location: Zürich
The AD797 is probably not stable when used in a basic inverting integrator (or any other with substantial capacitive feedback) application. Don't know how AP solved this, but I have used a small resistor (150-220 Ohm) in series with the inverting input. If you can't stand the noise penalty, parallel the resistor with a wideband inductor.

Samuel
  Reply With Quote
Old 13th March 2013, 06:55 PM   #1848
RNMarsh is offline RNMarsh  United States
diyAudio Member
 
RNMarsh's Avatar
 
Join Date: May 2012
Location: 2457 Cascade Trail; Cool, CA. 95614
Ok... Thx SG. Thats what I am looking for -- practical app info. Not trade secrets.
I've seen buffers driving osc opamps input -- presumably to provide low source Z on the osc opamp input (?). But a small R ll L is easy to try if I run into trouble.

Thx-RNMarsh

Last edited by RNMarsh; 13th March 2013 at 07:01 PM.
  Reply With Quote
Old 18th March 2013, 07:42 PM   #1849
Ite is offline Ite  Netherlands
diyAudio Member
 
Join Date: Jul 2009
Hi,


Having zero experience with low distortion oscillators, but after reading this thread I was thinking that this could be a candidate for a detector.

Precision Envelope Detector with 0.032% Total Harmonic Distortion

It was mentioned a few years ago on the LTspice forum by Mike Monett


Ite
  Reply With Quote
Old 19th March 2013, 08:46 AM   #1850
RNMarsh is offline RNMarsh  United States
diyAudio Member
 
RNMarsh's Avatar
 
Join Date: May 2012
Location: 2457 Cascade Trail; Cool, CA. 95614
Well I recieved the AD797 today and went direct to the KH4402B and yanked the LT1468 and put the AD in its place as the oscillator. yes, i added the 50pf.

Here is the result in a nut shell --> The noise dropped about 6dB and the THD+N dropped 3-4 dB's from 1KHz to 10Khz. Not a huge change but I'll take it. The oscillator THD+N is .00009- .0001% at 1KHz and .00015% at 10Khz from the direct out from the oscillator port (7v rms). Adjust the 10-turn AVC trim pot (R145) for lowest THD at 10Khz.

The lowered noise floor is now showing me junk I had not seen before (like ps harmonics so i beefed up the filtering on the ps) and allows me to see the individual harmonics better.

Thx-RNMarsh

Last edited by RNMarsh; 19th March 2013 at 08:54 AM.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

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


Similar Threads
Thread Thread Starter Forum Replies Last Post
Radford Low Distortion Oscillator Series 2 audiomik Equipment & Tools 21 19th February 2014 10:46 AM
ultra-low distortion audio oscillator geekysuavo Analog Line Level 16 26th March 2013 03:04 PM
Low distortion oscillator? rjm Equipment & Tools 30 4th May 2011 10:45 PM
Can we improve this low distortion sine oscillator ? gaetan8888 Solid State 22 29th March 2009 12:30 PM
Simple, low distortion 1kHz oscillator jackinnj Solid State 4 6th October 2003 03:58 AM


New To Site? Need Help?

All times are GMT. The time now is 09:11 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright ©1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2