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How to connect a quartz crystal?

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Lac

New Member
I have got one of those small crystals, packed in a silver package, low-profile, two pins. How do I connect it so that I get the output that is printed on it (7,680)?

Cheers!
Lac.
 

stevez

Active Member
It sounds like you are looking for an AC output at the crystal frequency so the crystal is only part of an oscillator. Crystals can also be used in filters.
 

Sebi

Active Member
The simply method to build it with CMOS inverters.
 

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Lac

New Member
w00t!? Don't they need power or anything? Just the crystal, a resistor and an inverter gate, and then I get my square 7,68Khz output?? That looks way too simple and mystic!

Cheers!
Lac.
 

Optikon

New Member
Lac said:
w00t!? Don't they need power or anything? Just the crystal, a resistor and an inverter gate, and then I get my square 7,68Khz output?? That looks way too simple and mystic!

Cheers!
Lac.

What would they need power for? THink of it.. it is just a piece of.. well crystal. There are no active circuits involved inside the crystal. The output power avalilable from the oscillator (not xtal) is from the inverters that sebi has shown.

A crystal by itself is a passive device of sorts. It only reacts to a stimulation input.
 

Nigel Goodwin

Super Moderator
Most Helpful Member
Lac said:
w00t!? Don't they need power or anything? Just the crystal, a resistor and an inverter gate, and then I get my square 7,68Khz output?? That looks way too simple and mystic!

The inverter obviously needs power, it's normal not to show power lines to chips in logic circuits.

Also the crystal is more likely to be 7.68MHz, rather than KHz.
 

Lac

New Member
Hm.. I can't get the crystal to generate any frequency at all. I used the first scematic posted over.

Cheers!
Lac.
 

Lac

New Member
Anyone know why I'm not getting any output? Does the resistor have to be 10M? Thats pretty high.

Cheers!
Lac.
 

udi_hakim

New Member
Try this circuit, if you dont have 74HC14 you can use any inverting HC gate...
 

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Lac

New Member
But doesn't the caps depend on the crystal frequency? I wasn't able to find any datasheets.

Cheers!
Lac.
 

udi_hakim

New Member
It depends but in wont cause the crystal not to vibrate, 1Mhz-40Mhz crystals should work with those capacitors that i gave you.

If you still don't get any frequency chack that you gave the logic gate VCC and GND !! sometimes it is forgotten by beginners.

Your crystal might damaged, try to replace it.
 
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