On Sat, 19 May 2012 14:31:48 -0500, Jim Yanik
wrote:

Jeff Liebermann wrote in
I once modified a vacuum fluorescent alarm clock to keep accurate
time. I opened the device, figured out what chip was used, looked at
the data sheet, and replaced the crappy RC oscillator with a 32KHz
clock crystal. When the AC power disappears, the display goes blank
and the internal 9v battery runs the clock. The problem is that the
battery drain was so high that it would kill the 9V battery in about 6
hrs. There was also no charging circuit. So, I replaced the 9V
battery with 4ea AA NiCd batteries (the clock chip would still run on
about 6VDC), and added a crude trickle charger.

was that a 32KHz crystal,or a 32KHz ceramic resonator?

Neither. It was a junk RC oscillator. Just a resistor and capacitor.
There was a reference designator on the PCB showing a ceramic
resonator, but what was installed was a resistor and a capacitor. My
replacement was a common 32KHz crystal that I found in my junk box.

I suspect it's the latter.that would explain the poor freq.stability.
You can trim up an XTAL oscillator.

Ceramic resonators aren't all that horrible and can also be tuned.
I've used plenty (usually Murata) for IF filters in radio designs at
455KHz and 10.7MHz. I will admit to matching them by frequency (bin
test) rather than deal with tuning and tweaking.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558