Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

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

Low-noise oscillator
Low-noise oscillator
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 3rd November 2002, 05:41 AM   #11
Jocko Homo is offline Jocko Homo  United States
Banned
 
Join Date: Feb 2002
Location: As far from the NOSsers as possible
I think it only puts out about 1 V rms or so. (I forget........yet another senior citizen moment.....)

The first go-round uses a '04 inverter set for a gain of 4 to square it up. Maybe next time I'll come up with something more exotic.

Jocko
  Reply With Quote
Old 3rd November 2002, 10:34 AM   #12
mrfeedback is offline mrfeedback  Australia
diyAudio Member
 
mrfeedback's Avatar
 
Join Date: Feb 2002
Location: Perth, Australia.
Thanks.

Eric.
  Reply With Quote
Old 13th November 2002, 08:57 PM   #13
pjkunz is offline pjkunz
diyAudio Member
 
Join Date: Oct 2001
Location: Palo Alto, CA
At what point (if any) would one need to adjust values for higher freq. crystals (~24Mhz) and is this freq. still in a good space for this design? I'm trying to put together a circuit with the CS8420 on the front and the output freq. is a fixed 256Fs. I'd like to be able to 'play' with the higher Fs ranges.

Also, Jocko mentions gain on a 7404, this is something I don't understand? It as simple as adding a R2/R1 input/feedback resistor ratio for an inverting opamp? I thought output level was independent of input level in TTL?

Thank you.
  Reply With Quote
Old 14th November 2002, 02:32 AM   #14
Jocko Homo is offline Jocko Homo  United States
Banned
 
Join Date: Feb 2002
Location: As far from the NOSsers as possible
Default Other frequencies

Scale C1 and C2. For 24 MHz, cut them in half. C3 & C4 are adjusted so that the crystal will resonate into the load it was cut for. You will need to know that.

As for the inverter........yep, you can configure it just like an op-amp. The output level of that circuit is too low to make a square wave without some gain somewhere.

Make sure that whatever you do has a stable PSU, or all that work to get low phase noise will be gobbled up by jitter in that circuit.

Jocko
  Reply With Quote
Old 14th November 2002, 06:20 AM   #15
pjkunz is offline pjkunz
diyAudio Member
 
Join Date: Oct 2001
Location: Palo Alto, CA
Thanks for the reply,

I'll breadboard it up and play with it a bit. Thanks for the circuit and thanks for the help. I'll do a little homework on this before I ask any follow up questions...

-Pete Kunz
  Reply With Quote
Old 14th November 2002, 07:01 AM   #16
pjkunz is offline pjkunz
diyAudio Member
 
Join Date: Oct 2001
Location: Palo Alto, CA
Default Crystal load..

Ah, so this is designed for a parallel res. Xtal?, I was confused when it was described as operating in the series res. mode. I looked closer at your posts a saw where i missed it. Mia Culpa.
  Reply With Quote
Old 16th November 2002, 11:07 AM   #17
Pjotr is offline Pjotr
diyAudio Member
 
Pjotr's Avatar
 
Join Date: Nov 2002
Location: Netherlands
Hi,

Here is some good reading about noise in oscillators.

  Reply With Quote
Old 16th November 2002, 02:17 PM   #18
Jocko Homo is offline Jocko Homo  United States
Banned
 
Join Date: Feb 2002
Location: As far from the NOSsers as possible
Almost all modern circuits place the crystal in the series resonant mode. The confusion arises when you start to specify the frequency.

A crystal that is said to be series resonant has its series resonant mode measured into a resistive load, say 50 ohms.

When you see a crystal with its resonant frequency specified at a parallel load of X pF (usually in the 20 - 32 pF range), the series resonant mode is measured with a load of that specifed capacitance, instead of the resisitive load.

Jocko
  Reply With Quote
Old 25th November 2002, 06:58 PM   #19
jwb is offline jwb  United States
diyAudio Member
 
jwb's Avatar
 
Join Date: Mar 2002
Location: San Francisco, USA
Send a message via AIM to jwb
Default How to squarify?

Hi Jocko. Guess I'm glad you didn't take that 90-year sabbatical, since I'm building your oscillator now. What is the lowest-jitter way to turn this into a square wave? An inverter is pretty simple, but I was thinking of buying some AD8611 for testing.
  Reply With Quote
Old 25th November 2002, 07:25 PM   #20
Jocko Homo is offline Jocko Homo  United States
Banned
 
Join Date: Feb 2002
Location: As far from the NOSsers as possible
Default Best way?

I dunno........soemone send me an expensive 'scope that measures jittter, and I'll tell everyone. (That's life when the lab you used to work in is gone..........)

Your approach is the same as mine. I would imagine a clean supply for the inverter, and not using exotic high-speed logic, would be good starting points.

Jocko
 

Reply


Low-noise oscillatorHide 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

Forum Jump

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 19 2nd November 2014 02:35 AM
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 06:46 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2020 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.00%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2020 DragonByte Technologies Ltd.
Copyright ©1999-2020 diyAudio
Wiki