Calculation of Load Capacitance of A Quartz Crystal

[faisal]

Hi,
I have a Quartz crystal (GSCX-39) of Golledge Electronics Ltd.
It has the frequency range of 3.579~70 MHz.
I want to use it in a fixed oscillator of 68.75 MHz.
What load capacitance should be used for this purpose.
Please post a complete circuit diagram if possibe alongwith all
the component values.
With Regards.

 

[Borber]

What do you mean by 3.579~70 MHz. Is your crystal made of elastic rubber?
Crystals are made for single, discrete frequency which can be pulled some few 10 ppm.

 

[faisal]

Perhaps yes the crystal is made up super elastic.
If you don't believe it find the data sheet and look for your self the
unbelievable super rubber crystal.
Best of Luck.


**broken link removed**

 

[Borber]

This type of crystal can be produced within the frequency range of 3.579~70 MHz, but only for specified frequency in this range.

 

[faisal]

You mean that I have to place the order of 68.75MHz.

 

[Borber]

Yes, all crystals are single frequency devices there exists no "elastic" type.

 

[faisal]

You mean that I have to place the order of 68.75MHz.

 

[brmadhukar]

Hi,
You chose your load capacitances while designing the oscillator inside the IC and once it is done you chose the crystal and the corresponding capacitors. If you can give that load capacitance we can match it.

B R
Madhukar

You may search for this in some of the crystal manufacturers web sites and find and AN

 

[biff44]

The dynamic range of the engineering skill level on this board has to be around 90 dB!