Quartz Kitchen Clock Movement

Sidereal Clock

Brooke Clarke 2007

Quartz Kitchen Clock
          Movement
Sidereal Clock




Quartz Movement
Sidereal Clock

Quartz Movement

Background

I have an idea for an improved clock and wanted to see how they are now made.  One side of the crystal has a trace that has 4 solder bridges which must terminate in capacitors on the IC under the epoxy blob.  Most likely in a binary weighting.  In the manufacturing process the free running frequency of the mechanism could be measured with a counter and then using a look up table the operator puts solder bridges on the proper pads.  In my case from top to bottom it's closed, closed, open, closed.

The impedance of watch crystals is extremely high so you can not probe the crystal circuit to measure the actual oscillation frequency.  What was done here is to use a pair of pogp probes to measure the coil drive pulse per second.  The length of that time interval should be exactly one second.

Drive

A positive pulse of 1.37 volts lasting 46 ms is followed 1 second later with a negative pulse of 1.37 volts lasting 46 ms.  This means that the IC uses a full H bridge circuit in order to get the bi polar drive from a single 1.5 volt AA cell.

Marking

On back of clock: Spartus, Quartz, Made in U.S.A.
On printed Circuit Board: 239/1-1,  Spartus, 57 11103 90

Disassemble

In order to use the movement when driven from a more precise time base than the on board crystal this movement was removed from an old kitchen clock.  This was done by prying the clear cover tabs and pushing so the clear cover could be removed.  Then the tabs paper dial and hands were removed.  Finally the movement was pushed out the front after the tabs on the frame were held back.

Spartus Quartz Clock
          Movement out of boxA number of plastic hooks hold the mechanism into the movement box.  All but one of these can be seen and with a small screwdriver pried enough to lift the mechanism up a little.  But the one under the printed circuit board seemed impossible to get to, so I cut a hole in the box.  Here a bottom view.  Note that three gears and a flat spring dropped off and have been reassembled for this photo.

The small white plastic circle at the 10 o'clock position of the leftmost gear is the armature.





Spartus Quartz Clock
          some gears removed




Here the three loose gears have been taken back out to show the metal magnetic path and the armature.  The armature is made from a permanent magnet, but I don't yet understand how it works.







Patents

2457637 ELECTRICAL MOTOR, Harrison D. Brailsford, Dec 28 1948, 310/46 ; 310/40MM; 310/40R - self starting (offset magnetics) pulsing clock drive motor, very low power
Fig 4 shows the structure
References:
362322 ELECTRIC MOTOR, EOBEET J. SHBBHY, May 3, 1887, 310/46 - 4 coil looks like start stop stock ticker drive
1367982 MOTOR, QTTSTAVE Lidseen, Feb 8, 1921, - AC/DC armature has teeth instead of windings
2185990 INDUCTION MOTOR, self starting
2214850 SELF-STARTING SYNCHRONOUS MOTOR, GE 1939 - uses permanent magnet for rotor
References:
1497394  Alternating Current Motor, Henry E. Warren (Warren Clock Co), Jun 10 1924, 310/163 ; 310/126 - self starting AC synchronous
3969642 Step motor for electronic timepiece

Sidereal Clock

In 2014 there was some interest in "Crazy Clocks" where the time would stop and then run fast.  To make these a small printed circuit board was put on the market with a number of different versions of the Crazy Clock and one of those versions was for a clock that tells sidereal time (Wiki).

To be useful a sidereal clock needs to tell Local Sidereal Time (LST) not some universal sidereal time, i.e. to take into account your longitude offset from the center of your time zone.  That way if you know the Right Ascension (Wiki) of a star that's the sidereal time when the star crosses your local North - South meridian.

To make this clock I started with a "10" Zulu Time 24 Hour Wall Clock" from eBay seller pilotmallaviationsuperstore and a "Crazy Clock" PCB with the Sidereal option.

Fig 1 Remove the clear plastic clock bezel by pressing the 3
fingers on the back in and out using a screw driver and remove.
Note the hands are all at midnight.
Pull off the second hand.
Remove the nut and minute hand.
Pull off the hour hand.
Remove the nut and washer and remove the Quartex 24h movement.
The instructions on how to open the Quartex are on the Crazy Clock web page.
Cut the two battery traces and the two motor traces as
shown below and solder wires as shown below.
Cut notches in the plastic cover to clear the wires.
Place "SIDEREAL" label over Zulu Time.
Solder red wire to Batt+ and black wire to Batt-.
I don't think it matters which motor wire goes to which terminal.
Sidereal
                  Clock
Fig 2  Crazy Clock board installed in clock.
Sidereal
                  Clock
Fig 3
Sidereal
                  Clock

To set the clock you can use the USNO LST web page: Compute Local Apparent Sidereal Time
PS. Since the clock comes with all three hands pointing to midnight, it makes is much easier to start up the clock at midnight LST or shortly thereafter.  That way you do not need to rotate the time setting dial a million turns.

Links

Low Power Time-base -

Lavet type stepping motor -


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