crystal osc

[be80be]

I look and haven't found any thing on here about having to ground your crystal osc. I have three 20Mhz crystals with just two wires to hook them up
with. They will not Oscillate if I don't ground the case. Ground the case and they work fine. Is this normal ?

 

[Hero999]

The case is normally connected to the 0V pin so if you don't connect it, it obviously won't work.

 

[be80be]

I ordered some of these Microprocessor, HC49SLF Crystal; 20MHz; +/- 30 ppm @ +25C; 20; 30 Ohms (Max.) Max. ESR they work with out grounding. There low profile Thru-Hole Crystals. They just got here to day. But the old ones I have, have to be grounded. What gets me is one did work but it stopped. And every thing I have seen has no ground on the crystal.

 

[Mr RB]

Re the old ones, did you put 22pF caps from each pin to ground?

 

[be80be]

Yes I did use capacitors on All of them I just want to no if any one grounds the case. I use CERAMIC RESONATOR most of the time but I was building a junebug and it uses a 20 mhz crystal oscillator. I have some like this
**broken link removed** there no place to ground it I ordered some like this
**broken link removed**
But a 20mhz and it worked. I was just wanting to no if there where xtals that didn't need the case grounded

 

[felis]

I don't ground HC-49 cases and crystals work just fine. I don't do anything special to them either. Are you trying to run your circuit off a battery by any chance?

 

[Nigel Goodwin]

Yes I did use capacitors on All of them I just want to no if any one grounds the case. I use CERAMIC RESONATOR most of the time but I was building a junebug and it uses a 20 mhz crystal oscillator. I have some like this
**broken link removed** there no place to ground it I ordered some like this
**broken link removed**
But a 20mhz and it worked. I was just wanting to no if there where xtals that didn't need the case grounded

There's no need to ground the case of a crystal, bear in mind you need to be ordering crystals for micro-controller applications - ones intended for RF use may be overtone crystals.

 

[be80be]

Thanks I use a lot of parts out of junk I find and I have a bunch of old nic cards that just happen to have 20 mhz crystals in them. I put together a a board last winter and it worked the oscillator ran at 20 mhz. I was testing some code for it and loaded it to the chip and it didn't work now, so I got to looking at the nic cards and the chips where laying flat on the pcb and a pad about the size of the chip. I solder a wire to the top of one and grounded it and it fired of and ran a 20 mhz. I ordered some just for

micro-controller applications

they work fine with no ground to the case.
I mostly use CERAMIC RESONATORS
I found a a easy way to to test them with a led and a delay time the blink and a little math works good Lol