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.
Exept when the 'transmition times' of the gates in series do have so much delay that they do not overlap each other.
H.
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:
In Out
- R - + - R -
¦
C
¦
GndJust my
Hp
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.
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.
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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Hi Herbert,
I ordered HC-43/U cold welded, the same I did send you for mesurement.
HC-47/U are more expensive.
Audio-distortion by clock jitter.
Gentlemen,
Because of this forum I thought over the distortion caused by clock jitter and updated the next document:
https://www.by-rutgers.nl/PDFiles/Audio Jitter.pdf
Perhaps this is helpful.
Cheers,
Herbert.
Gentlemen,
Because of this forum I thought over the distortion caused by clock jitter and updated the next document:
https://www.by-rutgers.nl/PDFiles/Audio Jitter.pdf
Perhaps this is helpful.
Cheers,
Herbert.
artikles in Dutch...
There are also a number of articles in Dutch about the subject on: by-rutgers.nl
Groet,
Herbert.
Edwin,
There are also a number of articles in Dutch about the subject on: by-rutgers.nl
Groet,
Herbert.
Well, This is a correct and valid statement.
However, it is very much common knowledge - nowadays, at least.
Due to their internal structure, JFETs have much less close in phase-noise than their countreparts.
Cheers..
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Hmmm, I am not sure abut this Herbert...
The way a 74HC04 buffer is designed internally leads to poor isolation, since it was not designed
to provide or be used as such (isolator).
There are things a designer can do to improve the inport to outport isolation of a 74HC04 based
buffer a little bit, but not by much.
Remember, a 74HC04 contains 3 inverters, not one.
Imho, it is not a suitable component for use in precision oscillators.
Cheers
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According to the datasheet it's a Hex-inverter... so 6 inverters.
...My dear, wonderful, fellow diy:ers, please do some CAREFULL research before you write...
Each gain block of a 74HC04 inverter (six of these inside a 74HC04 chip) contains three series-coupled
inverters: one inverter in the middle, sandwitched between two, so-called ”buffers”..
In contrast, each gain-block of a 74HCU04 inverter (six of these inside a 74HCU04 chip) contains only ONE inverter.
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What's wrong with my interpretation of this datasheet? http://www.onsemi.com/pub_link/Collateral/74HC04.REV1.PDF
It says hex-inverter, the datasheet shows 6 inverters.... how come, that suddenly would be quite different? I think "if it sounds like a duck and looks like a duck, it probably is a duck..." So, why would reality be different from what the datasheet says?
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