Should there really be equal amplitude on both pins? Considering that one
is driving the xtal andthe other is not (only an input), I would naievely
assume that the amplitude on the driving pin should be slightly higher. In
fact, I never have problems with 4MHz,10MHz,or 20MHz xtal startup in my
projects,and my scope usually shows one pin at about 3v p-p and the other
at 4v p-p If I recall correctly. True, my scope probe is not very low cap
(its a 10/1 divider 100MHz probe with about 15pF of capacitance).

Sean

At 03:59 AM 7/1/99 -0700, you wrote:
>THe method I use is to place 2 variables one on either pin and adjust for
>1.correct frequency and 2. equal amplitude on both pins... Requires a VERY
>low cap scope probe and sometimes a buffer amp (for the counter (HP5315A))
>I use a 100/1 divider probe. This is a procedure I do EVERY time I use a
>new type or frequency crystal... seems to be stable...
>It works really well for ceramic resonator types.
>
>                Robert K. Johnson
>                rkj1@ix.netcom.com
>
>At 09:53 PM 6/30/99 -0700, you wrote:
>>Does anyone have a method for finding the specified load capacitance for a
>>given crystal? aside from just using variable capacitors?
>>
>>--------------------------------------------------------------------------
----
>>A member of the PI-100 Club:
>>3.1415926535897932384626433832795028841971693993751
>>058209749445923078164062862089986280348253421170679
>>
>>On Wed, 30 Jun 1999, Dave VanHorn wrote:
>>
>>> > I am using the "usual" oscillator construction with two fixed caps to
>>> > ground, one at each end of the crystal (120pf in this case).
>>>
>>>
>>> Try using the actual value of load capacitance specified for that crystal.
>>> No spec?... Well, buy one with a spec?
>>> They are extremely accurate, in a properly constructed circuit.
>>>
>
|
| Sean Breheny
| Amateur Radio Callsign: KA3YXM
| Electrical Engineering Student
\--------------=----------------
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