32.768kHz Crystal - Polarity?

Thread Starter

demonGeek

Joined Feb 27, 2009
7
I'm about to solder up a PCB containing this 32.768kHz Crystal and there's a square pad on one of the legs which is used elsewhere on the board to indicate polarity.

Is the crystal is polarized and, if so, how do I tell?

Many thanks.

- Adam
 

Wendy

Joined Mar 24, 2008
21,840
I've never heard of a crystal having polarity, so I'm going to go out on a limb and say they aren't.
 

Thread Starter

demonGeek

Joined Feb 27, 2009
7
Thanks Bill - I didn't think it was polarized but it's the first time I've used one and I didn't want to guess wrong!

- Adam
 

wr8y

Joined Sep 16, 2008
232
I'v soldered a lot of crystals in place since 1980 and the only ones that are (sometimes) polarized are those in crystal filter circuits - but even then, they will have three legs! (There will usually be a dot or dimple at one end, this indicates polarity.) But these are not crystals to be used in an oscillator - they are being used as filters.
 

steveb

Joined Jul 3, 2008
2,431
If you hook a watch crystal up with reverse polarity, time will run backwards. :p
 
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