Low-noise oscillator - diyAudio
Go Back   Home > Forums > Source & Line > Digital Source

Digital Source Digital Players and Recorders: CD , SACD , Tape, Memory Card, etc.

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 21st September 2002, 03:45 AM   #1
Banned
 
Join Date: Feb 2002
Location: As far from the NOSsers as possible
Default Low-noise oscillator

I think there was a thread about this some time ago.......just can't find it. Anyway, it is probably too old for any of us to remember what we were arguing, er, ah, discussing.

Anyway......here is a slightly different version. The idea was inspired (or ripped off.....) from yet another ham radio book. The change is that it uses a common-base stage (Elso.....are you reading this......?) at Q2; instead of a 22 ohm resistor to pick off the crystal current. The input Z of this stage is around 5 ohms, so there is somewhat less Q degradation.

Jocko
Attached Images
File Type: gif osc3.gif (6.0 KB, 6012 views)
  Reply With Quote
Old 21st September 2002, 03:59 AM   #2
Banned
 
Join Date: Feb 2002
Location: Dallas,Texas
Default Cool man but..... or unsolicitated design review

Doesn't C8 go to the emmiter and not the collector of Q3?

H.H.
  Reply With Quote
Old 21st September 2002, 04:00 AM   #3
Banned
 
Join Date: Feb 2002
Location: As far from the NOSsers as possible
Default Spec'ing crystals

I know that sooner or later, some wiseguy will fuss about a capacitor in series with the crystal. So for those of you who are new at this.....and for those that ought to know better, but don't.......

This circuit operates in the series-resonant mode. When ordering a crystal, you can either specify series-resonant frequency, or a parallel-resonant one.

Both cases refer to the frequency at which the crystal exhibits a series resonant frequency, usually in the range of tens of ohms. This is not the anti-resonant frequency, which is the equivalent of a parallel tuned circuit, and therefore in the range of many kilohms.

For a crystal spec'ed for series resonance, they measure the resonant frequency with only a resistive load, usually 50 ohms. The only capacitance is the stray holder capacitance, etc., usually around 6 pF.

When you spec for "parallel resonant", they measure the series resonant point using the specified load capacitance in parallel with the crystal. Typical values are 20 and 32 pF. This frequency is a few kilohertz higher when measured this way.

Most crystals you see in parts catalogs are spec'ed for parallel resonance, as the most common clock circuit around uses that type. It might be easier to order a crystal that way, because it will work in any circuit. In the case of a Butler oscillator, you can simply put a capacitor of the proper value in series with the crystal. The circuit will work just as well.

Jocko
  Reply With Quote
Old 21st September 2002, 04:02 AM   #4
Banned
 
Join Date: Feb 2002
Location: As far from the NOSsers as possible
Default Doesn't C8 go to the emmiter and not the collector of Q3?

YES!
  Reply With Quote
Old 21st September 2002, 04:03 AM   #5
Banned
 
Join Date: Feb 2002
Location: Dallas,Texas
Talking Yes!

Do I win a prize or anything?

H.H.
  Reply With Quote
Old 21st September 2002, 04:08 AM   #6
Banned
 
Join Date: Feb 2002
Location: As far from the NOSsers as possible
Default NO!!!!!!!

You might want to help me complain how many times I tried uploading the correct version.

Oh well, it is not my server that will be clogged up.
Attached Images
File Type: gif osc3.gif (6.0 KB, 5456 views)
  Reply With Quote
Old 31st October 2002, 10:05 PM   #7
Banned
 
Join Date: Feb 2002
Location: As far from the NOSsers as possible
Default A slightly different version....

The common-base stage runs at around 50 mA. (Are you reading this, Elso?)

So........is anyone going to try to build this? I know what it sounds like, but what do I know.

Jocko
Attached Images
File Type: gif osc.gif (7.8 KB, 5571 views)
  Reply With Quote
Old 31st October 2002, 11:02 PM   #8
diyAudio Member
 
mrfeedback's Avatar
 
Join Date: Feb 2002
Location: Perth, Australia.
Jocko, I believe you that this circuit sounds good.
Q - the output is sinewave ?
If so, is it better to feed your oscillator output into a squaring circuit first before feeding into the oscillator pin of DSP/DAC to avoid internal sqaring/timing error ?.

Eric.
  Reply With Quote
Old 1st November 2002, 01:37 AM   #9
Banned
 
Join Date: Feb 2002
Location: As far from the NOSsers as possible
Default Sine wave......

And low harmonics too. That way you can put it outside of your player, feed it in at a low level without radiating crap all over the place. Then square it up once inside.

Also will let you feed it into a D/A box using.....say....a DIR1703 to sync up things.

Jocko
  Reply With Quote
Old 2nd November 2002, 11:50 AM   #10
diyAudio Member
 
mrfeedback's Avatar
 
Join Date: Feb 2002
Location: Perth, Australia.
Default Then square it up once inside.

Reciever info recieved and thankyou.
If using your oscillator circuit inside a one box cd machine (CD-94), would you square the sinewave before feeding the DSP/DAC osc input pin, and if so how ?. (some kind of data slicer/schmitt/74HCT etc or something or discrete ? - keeping in mind your previous snippets/advice of some gate devices causing zero/little backfeeding - can you remember ?).
A two box CD player is on the future wish list - I have various and plenty standard mechanisms and servo/dsp/system junked machines to play with and experiment with.
On this subject, I reckon different Laser pickups cause different sounds.

Eric.
  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
Use of a Ribidum Oscillator as refrence oscillator in a DAC Mark A. Gulbrandsen Digital Line Level 18 2nd January 2009 09:57 PM
10 MHz oscillator possible to use ? Bernhard Digital Source 7 28th August 2007 09:07 PM
Look at this 42V/20A max PSU, and at this low THD oscillator. rephil Everything Else 3 6th August 2006 08:04 PM


New To Site? Need Help?

All times are GMT. The time now is 04:13 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