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Author Topic: XTAL Oscillator  (Read 22466 times)
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Posts: 337
GL,

I retract what I said before, now that I'm looking at your scope shots.

You have a beautiful and pure frequency!  I don't see any harmonics!  The last graph is so common to see with digital scopes when it's zoomed out, so there is no 5 hz modulating frequency.  That patern you're seeing is the beat frequency between your digital display and your pure signal.

Good job, you had it working all along!

EM

EM,

I'm used to use analog scopes.

Are you saying that this digital scope is just fooling me?

I will dig out my old 20MHz analog scope and check the oscillator, later on.

Thanks for the help. :-)

GL.
   

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It's not as complicated as it may seem...
I concur with EM.
   

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Wow i have learnt something as well   8) explains why the cap did not work then.
   
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All,

I went to my lab and did dig out the old 20MHz analog o-scope.
I saw a beautiful clean sinus at 77.5KHz on the scope. :-)

So I did learn something new today, read the digital scope manual. LOL

Thank you all for the help in this matter. :-)

GL.
   
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   Guess I had better apologize  for my comment. Using a 4069 it would seem to me
you should get harmonics. Guess not. 

   On the other hand, looks like I dont want one of the new scopes either. Have 3
older ones and think I will stay with them. The Tek needs a bit of work but think
now its worth it.

   To top all that, looks like I found the perfect osc for my little project as well. Thanks
all for putting up with me.

thay
   
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  Guess I had better apologize  for my comment. Using a 4069 it would seem to me
you should get harmonics. Guess not.  

   On the other hand, looks like I dont want one of the new scopes either. Have 3
older ones and think I will stay with them. The Tek needs a bit of work but think
now its worth it.

   To top all that, looks like I found the perfect osc for my little project as well. Thanks
all for putting up with me.

thay


Thay,

No problem. :-)

Well now I can move on with the rest of my project.
Currently writing firmware for my new circuit.
Attached is a look at my new board. :-)

GL.
   

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The third scope shot in Groundloop's reply #22 is similar
to the classic Supressed Carrier DSB waveform.  The
envelope peaks are rounded and the nulls are very sharp.
This is characteristic of two equal amplitude signals which
are close to the same frequency.  In Single Sideband tests
signals of 1.0 KHz and 3.0 KHz are used to evaluate the
Balanced Modulator for carrier leakage.  With no carrier
present the waveforms are exactly as depicted in the shot.

What is it about the Digital Scope which produces such a
spurious display?


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Mainstream establishment orthodoxy is essentially a religion, as fake and power-serving as any other, and if you want to work in mainstream politics or media you need to demonstrate that you are a member of that religion.  - Caitlin Johnstone
   

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What are you building GL not sure i have read that yet? maybe i missed it
Looks good as usual  O0
   
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What are you building GL not sure i have read that yet? maybe i missed it
Looks good as usual  O0

Peter,

I'm building a DCF77 simulator. The unit uses a GPS to get date and time
and has a built in modulator to make the same AM modulated 1 bit / Sec
data stream, transmitting on 77.5KHz, as the original atomic clock in Germany.
My unit has a VERY low power and the DCF77 clock must be within 10cm of the
antenna. Has not got my firmware to run OK yet, but is working on that. I will
not put this project on the net. But you can find others that have built similar
projects by Google it. My unit is special because of the small size.

GL.
   

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I see  O0 quiet handy if you have a time switched tarriff electricity meter then  C.C
   
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I see  O0 quiet handy if you have a time switched tarriff electricity meter then  C.C

Peter,

I do not think that electricity meters use DCF77 because of limited RF coverage.
The one I have seen uses the Internet via RF to connect to the power suppliers.

My unit may become handy in areas where the DCF77 has no radio coverage
and people have clocks that uses the DCF77 to get the correct time. The DCF77
transmitter in Germany has a RF coverage of approx. 2000Km. So if you have
a unit that relay on the DCF77 time signal, and your are outside of that coverage,
then you have to provide that signal yourself. :-)

GL.

 
   

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must be different to the UK system then, they use it here to sync the meter's and clocks, Ive never really looked into it but i think theres a big transmitter somewhere that sends out the time signal.
   
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