About Crystals in microcontroller......

[ujjval rathod]

I have a question that if we use external quartz crystal in Microcontroller and connect it to battery... Crystal gives regular and very accurate electrical frequency... But it should get mechanical vibration from somewhere to give electrical pulses... From where it receives mechanical vibrations?

 

[Nidum]

https://en.wikipedia.org/wiki/Crystal_oscillator

 

[Runei]

The crystal does not do anything by itself.

The quartz-crystal is a piezoelectric material, and you can apply a voltage across it. The crystal, when it is connected the microcontroller, becomes part of an internal oscillator circuit.

There are different ways to make an oscillator circuit. Try reading through the following link:

http://www.electronics-tutorials.ws/oscillator/crystal.html

So just to summarize: The crystal does not output an electrical frequency.

 

[meBigGuy]

The quartz crystal essentially behaves like a high Q LC circuit tuned to the specified frequency. Put it in the proper oscillator circuit and load it correctly and it will cause the circuit to oscillate at the correct frequency.

Back in the olden days we could change crystal frequencies slightly by sanding the quartz or scribbling on it with pencil lead.