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-   -   The Well Tempered Master Clock - Building a low phase noise/jitter crystal oscillator (https://www.diyaudio.com/forums/digital-line-level/261651-tempered-master-clock-building-low-phase-noise-jitter-crystal-oscillator.html)

Herbert Rutgers 27th March 2016 04:51 PM

Quote:

Originally Posted by stormsonic (https://www.diyaudio.com/forums/digital-line-level/261651-tempered-master-clock-building-low-phase-noise-jitter-crystal-oscillator-post4662638.html#post4662638)
why are you using 74HC04 and not 74HCU04 ?

The 74HC04 gives larger delay which is helpful for the isolation of the 'world behind' the oscillator and the oscillator. I mean the buffer function. The oscillator does not see its load and the other disturbing digital signals like audio related data.....
This works best with three stages 74HC04. The last stage with three in parallel is only for the low output impedance. With 30 ohm (I think by hart) in series the output impedance is 50 ohm, and with 6.5V power supply the output voltage is nearly 5 volt.
Cheers,
Herbert.

Herbert Rutgers 27th March 2016 04:55 PM

[QUOTE=gentlevoice;4662698 the general guidelines for good HF design (and leaving out the ground plane in certain areas - right ... ?) ...

Cheers,

Jesper[/QUOTE]

Absolutely right!
H.

1audio 27th March 2016 08:43 PM

My understanding was that faster gates would have more reverse isolation than slower gates. With the shorter transition times the link from out to in would be smaller. Am I mistaken? The higher drive makes good sense.

miklos 28th March 2016 07:35 AM

Hello Andrea,
I sent you €38.85 on 02/03/2016, but still no trace of the crystal.
Can you please look in to this matter?
Thanks.

Herbert Rutgers 28th March 2016 08:19 AM

Quote:

Originally Posted by 1audio (https://www.diyaudio.com/forums/digital-line-level/261651-tempered-master-clock-building-low-phase-noise-jitter-crystal-oscillator-post4663019.html#post4663019)
With the shorter transition times the link from out to in would be smaller. Am I mistaken?

Exept when the 'transmition times' of the gates in series do have so much delay that they do not overlap each other.
H.

HpW 28th March 2016 09:48 AM

Quote:

Originally Posted by Herbert Rutgers (https://www.diyaudio.com/forums/digital-line-level/261651-tempered-master-clock-building-low-phase-noise-jitter-crystal-oscillator-post4662827.html#post4662827)
The 74HC04 gives larger delay which is helpful for the isolation of the 'world behind' the oscillator and the oscillator.

Basically there are 3 parts: Oscillator, Level Converter (Amplifier) & Output Level driver. Each part should be isolated power wise do the noise introduced. Also using an Amplifier chip & buffer should be avoided do the internal chip bonding wire wires.

Means for the Amplifier:

- All HC logic user guides simple do not recommend to use a HC04 inverter, while simple this has an output buffer where the HCU04 has not and is the chip to use as an Amplifier.

- Also the HCU04 requires a certain operation point at the input.

- Currently there are also single chip HCU04 available for simple use and
lower internal chip bonding wires

- This DC base should not catch up any noise form the power while this gets amplified too!

- At the old days, there was a simple self base circuit given for this

PHP Code:

   In               Out
   
-  + - -
           

           C
           
          Gnd 

Just my :cheers:

Hp

QSerraTico_Tico 28th March 2016 12:08 PM

Jitter is confused here with propagation delay.
It's not the same spec.

andrea_mori 28th March 2016 12:44 PM

Quote:

Originally Posted by miklos (https://www.diyaudio.com/forums/digital-line-level/261651-tempered-master-clock-building-low-phase-noise-jitter-crystal-oscillator-post4663487.html#post4663487)
Hello Andrea,
I sent you 38.85 on 02/03/2016, but still no trace of the crystal.
Can you please look in to this matter?
Thanks.

The crystals have been ordered to Laptech (and paid in advance) but they have not yet told me the date of delivery.
I expect to receive the crystals within the end of April. Then I will ship them to all the members.

miklos 29th March 2016 06:21 AM

Thanks

Herbert Rutgers 29th March 2016 06:58 AM

Andrea,
which types of Xtals did you order with Laptech? Is it a good idea to order for:

HC 37/U because Q>2.10^6 and little microphonics because of 4 point mounting,
or
HC 47/U, Q>2.10^6 larger and cheaper ?

Which type from Laptech did you send me for measurements way back then?

Cheers,
Herbert.


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