Replacing laptop cpu

[jdow]

On 2015-05-25 06:18, Tim wrote:
> On Mon, 2015-05-25 at 03:56 -0500, g wrote:
>> would you presume dropping of voltage would cause a great amount of
>> change in a crystal's oscillation?
>
> Seems highly tangental to the prior conversation, but possibly yes.
>
> Essentially, it's a mechanical vibration, even at a very high rate.
>
> If you gently pluck a guitar string while tuning it, it doesn't play the
> same note as if you very harshly pluck the string.  Or, to put in
> another way, you pluck a string and let it ring, the note it plays goes
> slightly flat before it peters out to not vibrating (the frequency
> decreases).
>
> So, I wouldn't be surprised if you kick a crystal with less voltage to
> make it swing than you usually do, it mightn't do it so fast.
>

How far do you expect it to change, Grasshopper? Inquiring and bemused minds 
want to know.



You are right in that in general changing the voltage on a crystal oscillator 
will change the output frequency. Generally this is of concern to people who 
build precision oscillators but not mere mortals such as computer users who are 
bold enough to try to "fix" things inside their computers. We're talking single 
digit parts per million frequency changes until the voltage gets low enough the 
oscillator becomes unstable which may not happen before the oscillator simply stops.

The crystal oscillator frequency will change at PPM levels as voltages get 
higher until one of two things happens, the crystal blank fractures or a 
component in the oscillator fries.

Crystal oscillators bear no more resemblance to a guitar string than a hydra 
bears to a gorilla. In one case both vibrate. In the other case both are living 
creatures using DNA.

I completely fail to see why you might be concerned about the oscillator 
producing a frequency of say 100.000000 MHz or 100.000100 MHz on a computer. The 
oscillator will vary as much as 100 ppm with modern floor sweeping crystals from 
oscillator to oscillator and over a wide temperature swing. The voltage induced 
changes will be small by comparison.

{^_^}	GPS Joanne

{^_^}