How to vary crystal frequency

[demetal]

Is there any possible method by which we can vary frequency of a crystal to few range.... for example.... can we generate 28.322Mhz from a 28 Mhz crystal by any additional circuit.... :roll:


Thanks

 

[prestonee]

You can apply a capacitor across the crystal, this will change its frequency and is commonly used.
-Pb

 

[betwixt]

Or an inductor will work but the amount by which you can 'pull' it is very small, probably no more than around 0.5% of it's fundamental frequency so you would be very unlikely to manage 322KHz from 28MHz (1.15%). You also lose some stability as you move further away form fundamental.

Brian.

 

[FvM]

The pulling range of usual crystals is below 1000 ppm respectively 0.1 %.

 

[mtwieg]

There's basically a direct inverse relationship between the stability/precision of a resonant element and its tuning range. Very high Q devices like crystals can only be pulled a tiny bit (hundreds of ppm, maybe 1000ppm if you're careful). Lower Q devices like ceramic resonators can be pulled a percent or so.

- - - Updated - - -

There's basically a direct inverse relationship between the stability/precision of a resonant element and its tuning range. Very high Q devices like crystals can only be pulled a tiny bit (hundreds of ppm, maybe 1000ppm if you're careful). Lower Q devices like ceramic resonators can be pulled a percent or so.

 

[demetal]

Thanks all... If it is possible to vary the frequency at least 0.5% by external capacitor or inductor.... How to calculate the value of those passive components for a particular frequency ,say for 0.5% increment of 28Mhz...