3 pin crystal?

[adamdb]

I am trying to make an AVR USB programmer out of scavenged parts and need a 12mHz crystal. I found one, but instead of just the normal 2 pins it has a 3rd wire that is soldered to the case. Do I hook this up like a normal crystal like this:

GND-->20ish pf cap-->crystal leg one-->AVR XTAL1 pin
GND-->20ish pf cap-->crystal leg two-->AVR XTAL2 pin

Or do I need to do something with that third wire? Connect it to ground?

Wasn't sure where else to ask this, but knew someone here would know.

By the way it is a Crystek, 12mHz, 9331TT if that means anything to anyone.

Of course, I could just order one, but why order one if I can make this work!

Thanks,
Adam

[jeffs555]

Just connect the 3rd wire to ground, or leave it unconnected. It is just for shielding purposes.

[Matt Edwards]

Have a look at the bottom of the Crystal. the middle pin will appear to be connected to the case. add this pin to ground or as already stated, leave it floating.

[adamdb]

Thanks! Just what I was hoping to hear.

Adam