Hi Manu,

I have long suspected that the reasons certain types of crystals and resona=
tors don't work in every application are the amount of phase shift or else =
the impedance, so it all ends up being too lossy to oscillate. But if you a=
dd more capacitance to push the phase, then you need more gain, which you m=
ay not have had enough to begin with.

By using multiple gates in series, you get both more gain and more phase sh=
ift, and it may work perfectly.

Cheerful regards, Bob

________________________________________
From: piclist-bounces@mit.edu <piclist-bounces@mit.edu> on behalf of Manu A=
braham=20
Sent: Friday, September 21, 2018 10:42 AM
To: Microcontroller discussion list - Public.
Subject: Re: [EE] testing a crystal

Hi Bob,

Thanks for the quick reply. I was wondering something like that,
but could not really get a foot on the topic where to start looking.

Why would it need more gates ? Larger delay ?

Additionally, I tried another 12MHz crystal with the 4060, that does appear
to work. NX5032GA-12MHZ-STD-CSK-4

http://www.ndk.com/images/products/catalog/c_NX5032GA_e.pdf

But unfortunately, I cannot replace the ABM8G with the NX5032, since it has
a different footprint. Feel really frustrated. :-/

That said, using a Piccolo http://www.ti.com/lit/ds/symlink/tms320f28069m.p=
df

I cannot really add any gates in there as it has a built in oscillator.
Have been trying to debug why the oscillator block wont become alive. :-)

This was the whole scenario, that I've trying to debug with the 4060.

Scratching my head still.

Thanks,

Manu



On Fri, Sep 21, 2018 at 10:53 PM, Bob Blick  wrote:
> Hi Manu,
>
> I did a survey of resonators a few years back, and basically there are so=
me resonator types that require more oscillator gain to operate.
>
> If you need it to work with your 4060 you might need to make a separate o=
scillator using multiple gate sections in series.
>
> Cheerful regards,
>
> Bob
>
> P.S. fixed tag. You need a beginning square bracket.
> ________________________________________
> From: piclist-bounces@mit.edu <piclist-bounces@mit.edu> on behalf of Manu=
 Abraham
> Sent: Friday, September 21, 2018 9:55 AM
> To: Microcontroller discussion list - Public.
> Subject: EE testing a crystal
>
> Hi,
>
> I have the following crystal, with a frequency of 12MHz.
>
> https://abracon.com/Resonators/ABM8G.pdf
>
> Soldered one of these onto the desired PCB, thought of testing the
> crystal using a HEF4060B by connecting between pins 9 and 10, the
> crude test which has worked over the years.
>
> Sadly there were no oscillations at all.
>
> The next thought was to do a dead bug style, the crystal. Did that
> too, but there seems to be no life at all.
>
> As a result, thinking that the crystal could be dead, tried a brand
> new exactly same ABM8G crystal in the dead bug style, which also
> showed no signs of life.
>
> Tried a 7.3728MHx crystal in it's position, that does show a clean
> 7.3728MHz oscillation
>
>
> I am just scratching my head, lost in thoughts.
>
> Any suggestions, anyone ?
>
> Thanks,
>
> Manu

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