Low Distortion Oscilator schematic anybody? - Page 2 - diyAudio
Go Back   Home > Forums > Amplifiers > Solid State
Home Forums Rules Articles diyAudio Store Gallery Wiki Blogs Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Solid State Talk all about solid state amplification.

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
Thread Tools Search this Thread
Old 9th September 2003, 06:55 PM   #11
diyAudio Member
Pjotr's Avatar
Join Date: Nov 2002
Location: Netherlands
Default Re: Re: Low Distortion Oscilator schematic anybody?

Have you considered an ordninary sound card?

The advantage of this is that you get a distortion profile, not just THD + noise. Here a picture of my 200 bucks 24 bit soundcard in loop through mode, line in connected to line out. Measuring ultra low distortion is not easy. Noise and hum entering through cables and caused by ground loops are not easy to cope with.

Good affordable software for an audio test bench can also be found here:


Attached Images
File Type: gif dist2496.gif (3.8 KB, 424 views)
  Reply With Quote
Old 9th September 2003, 07:07 PM   #12
PMA is online now PMA  Europe
diyAudio Member
PMA's Avatar
Join Date: Apr 2002
Location: Prague
That's perfect. We've always had problems with oscillator implemented in the card, so decided to build an external ..
  Reply With Quote
Old 10th September 2003, 11:17 AM   #13
ALW is offline ALW  United Kingdom
diyAudio Member
Join Date: Jun 2001
Location: UK
The M-Audio Audiphile 24/96 can manage this with ease, and it's not that expensive.

Makes a good basis for a PC-based analyser.

Frequency response (from 40 Hz to 15 kHz), dB: +0.00, -0.00
Noise level, dB (A): -101.4
Dynamic range, dB (A): 101.0
THD, %: 0.0003
IMD, %: 0.0042
Stereo crosstalk, dB: -99.3
Attached Images
File Type: png thd.png (12.6 KB, 339 views)
  Reply With Quote
Old 10th September 2003, 01:54 PM   #14
PMA is online now PMA  Europe
diyAudio Member
PMA's Avatar
Join Date: Apr 2002
Location: Prague
Yes - now you can get valuable results.
  Reply With Quote
Old 11th September 2003, 10:42 PM   #15
diyAudio Member
Join Date: Jul 2001
Location: The Netherlands

First, thanks for or the links. I got around measuring my own sound card in 'loop through' mode, but was a bit dissapointed... I use a asus 8NX-X motherboard with sound-on-board. The specs are not that good.

So I read more about the wien-bridge, I think I understand the principles now...

Got myself a few lamp: I understand now that:
-you need low current draw to make it easy for the opamp to drive
-you need large mass to keep thermal-dissipation time constant large
-all lamps typically have a 1/10th impedance at zero current compared to rated current and you need about 1/10th of the rated current to make some practical use of the possitive themperature thingy...

So a 230Volt / 3Watt lamp would be around 1.2KOhm at zero current and 12KOhm at rated current: perfect, it will draw about 1mA (that's low enough), requires 3k3 feedback resistor (high enough not to stress the opamp), and gives about 3 Volt out.

I got 0.006 % distortion, allmost all second harmonic (????) using a NE5534 opamp. I also used ad797, opa627, opa134, opa228, LT1028, LT1115, op27, op177, u747, lm308, .. alllllllllll my opamp in stock actually .... ne5534 had lowest distortion, which supprissed me... The high speed LT1028, ad797 and LT1115 all needed a output resistor of 470 or higher to drive my coax BNC cable.. the NE5534 worked fine without it.

Then I build a two-opamp inverting mode wien-bridge that help to limmit common-mode distortion... it works! ... 0.0045% using a opa134.. opa132 and LT1113 has slightly higher distortion, but it was difficult to see.

I also used a 6V/50mA lamp (much to fast setteling time, high distortion) and a 230V/15W lamp, which, I think, needed to much current to give low distortion. The 230V/3W lamp seems perfect, time comstant is about 0.8 sec.

Well that it for now .... goodnight
  Reply With Quote
Old 12th September 2003, 05:59 AM   #16
diyAudio Member
Join Date: Jan 2002
Location: Moscow
This scheme from Electronics World & Wireless World 6/98 p.p.485-489
3-thd harm.=0.0004%(-88dB) , 5-th = 0.00007%(-104dB)
Best regards!
Attached Files
File Type: zip gener.zip (13.9 KB, 95 views)
  Reply With Quote
Old 12th September 2003, 06:22 AM   #17
Electrons are yellow and more is better!
diyAudio Member
peranders's Avatar
Join Date: Apr 2002
Location: Göteborg, Sweden
Blog Entries: 4
Alex, you have a couple of zeros too much.

-80 dB = 0.01%
-100 dB = 0.001%
/Per-Anders (my first name) or P-A as my friends call me
PA03 LM4780 amplifier group buy, SIGN UP HERE for the group buy 0 boards left. 118 paid.
  Reply With Quote
Old 12th September 2003, 06:36 AM   #18
PMA is online now PMA  Europe
diyAudio Member
PMA's Avatar
Join Date: Apr 2002
Location: Prague
Per is right.
-88dB = 0.004%
-104dB = 0.0006%
  Reply With Quote
Old 12th September 2003, 07:21 AM   #19
diyAudio Member
Join Date: Jan 2002
Location: Moscow
Sorry, but I have not a original paper, only abstract in other magazine.
  Reply With Quote


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
need schematic for 12au7a distortion overdrive and fuzz prorms Instruments and Amps 4 4th February 2008 05:53 PM
Have anyone a triangle oscilator? Whortless Class D 0 6th June 2006 10:43 AM
CD4001BE Oscilator hayes Digital Source 0 1st May 2004 07:26 PM
not gate oscilator sss Digital Source 6 24th October 2003 08:03 PM
oscilator needed sss Digital Source 5 19th October 2003 02:32 AM

New To Site? Need Help?

All times are GMT. The time now is 08:26 PM.

vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright ©1999-2017 diyAudio

Content Relevant URLs by vBSEO 3.3.2