Jeff Liebermann wrote in message
...
On Sat, 19 May 2012 07:53:46 -0700, "William Sommerwerck"
wrote:

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.

The world's first clock-radio with an all-electronic digital clock -- a
GE,
which I still have, 40 years after I bought it (!!!) -- used a
nicad-powered
oscillator running at ~ 60Hz to keep the timer going. I don't think it
ran
more than about 10 minutes.

I think I remember seeing those. Todays version will last about a
year before something blows or it falls apart. Progress?

Way back in college daze (1960's), one of my friends was trying to
devise a method of running a motor drive electric clock during power
outages. I designed a line sync blocking oscillator, that ran in sync
with the 60Hz power line frequency when that was present, but ran off
battery power at roughly 60Hz when that disappeared. To get
sufficient power to run the clock, it had two 2N3055 transistors
playing push-pull oscillator to a small power transformer. It was
big, noisy, and ugly, but worked quite well. Keeping the wet cell
battery charged was the major challenge. We were thinking of
manufacturing these, but was talked out of the idea by someone with
more marketing sense than us.

The analog wall clocks in high skool were all wired to central time
controller. Curious as to how it worked, I dragged an oscilloscope
into the main hallway to clip onto the only accessible wires I could
find. Every 15 minutes, a sync pulse would appear on the line,
resetting the clocks to the nearest 15 minutes. Every hour, two
pulses would reset the clocks to the nearest hour. At noon and
midnight, 5 pulses would reset the clocks to midnight. Unfortunately,
gathering this intelligence required almost constant monitoring, which
attract too much attention. I was caught before I could make the
clocks run backwards. Not a great start for my first attempt at
hacking.

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



I used to "wind-up" my father by stopping the synchronus-motor clock and
with a bit of backwards pressure on the seconds hand , while turning the
power back on , the clock would go backwards