Standard Electric 'standard' master clock... '40s?

Discussion in 'Electric Horology' started by bruce linde, Jul 17, 2019.

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  1. bruce linde

    bruce linde Technical Admin
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    Nov 13, 2011
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    just snagged this off of craigslist... listed for $10 but offered $20 if he would deliver it. :cool:

    it runs... haven't had a chance to clean it up or play with it except to note that it seems to trigger a pulse that lasts a couple of seconds and then move the hands when the pulse stops... see red arrow in pic pointing to nylon piece that rotates 360 degrees/minute... the connection is held for a few seconds and then let up.

    any info or insights would be most appreciated, thx.

    IMG_7878.JPG IMG_7881.JPG IMG_7879.JPG IMG_7880.JPG IMG_7883.JPG IMG_7882.JPG IMG_7884.JPG
     
  2. gleber

    gleber Registered User

    Jun 15, 2015
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    Well ain't that cool. Lots of switched to fiddle with.. and blinky lights and a Volt meter too! I have my eye out for a slave clock now that I have a master clock. I saw a slave movement-only on CL listed at $30 and it was snatched right up. My IBM instructions say the contacts should close for 2 seconds (at x:59:58)

    Tom
     
  3. Jim Andrews

    Jim Andrews Registered User
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    the price was right. Nice find!
     
  4. bruce linde

    bruce linde Technical Admin
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    it's kind of hard to find info given the generic name... anybody able to point me toward more docs or info?
     
  5. Jim Andrews

    Jim Andrews Registered User
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    Bruce, there's one on eBay now that you might take a look at. The outside is identical to yours, but the inside is completely different. It appears to me that someone did a major upgrade to your clock at some point. There is some paper documentation with that clock that would give you maybe a few clues as well. good luck
     
  6. novicetimekeeper

    novicetimekeeper Registered User

    Jul 26, 2015
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    Has it had a new movement and power supply? It doesn't all look 1940s.
     
  7. skruft

    skruft Registered User
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    This is very interesting. I believe what someone has done is, removed the original master clock mechanism that was in here, replaced the master clock movement on the front with a Standard "AR3" slave clock movement, and fabricated a new basic clock impulser, using a regular electric clock motor that turns at 1rpm and activates a microswitch every minute. This last is what you see in the metal case in the cabinet. He has installed several circuits instead of only one, probably to run four external slave clocks separately. I made a simpler version of this once.

    What all this lacks is any way to automatically activate the resetting mechanisms in slave clocks, if there is a power failure or some other problem. All it can do is send the routine impulses every minute. I think this is why there are several circuits. This way the owner can control each slave clock separately, by either manually advancing it one minute at a time, or turning it off and letting the master clock catch up.

    From the power supply I assume this sends out 24 volts DC.

    The slave clock installed in the front looks like a Standard AR3, which would usually have three wires running to it, but I see that one has been left unconnected, because it is not needed to just advance the clock once every minute. The loose wire relates to automatic correction of the slave clock.

    So, this should work with any simple "minute impulse" slave clock that runs on 24 volts DC, or else the voltage could be changed or varied without too much trouble. It just will not automatically reset the slave clocks and will not run any slave clock that needs any input other than one impulse a minute. For this purpose, generally the exact duration of the minute impulse does not matter if it is not more than one or two seconds.
     
  8. bruce linde

    bruce linde Technical Admin
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    replaced the microswitch and it's running... i think skruft is spot on. it's pretty easy to lift the left-most ratchet thingey to reset the clock to close to the current time and then manually advance until on the money.
     

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