American Simplex US Capitol Clock

Jmeechie

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Hi all,
Here’s an interesting clock I’ve been offered and am trying to figure out, what exactly this clock is! I realize it’s a Simplex 110v, but look at all the goodies inside, as well as the lights at the 4, 8, 12, 48, 52, 56 and top of the hour minutes? Supposedly this was in the US Capitol Building chamber and was replaced when they switched to digital clocks. I’m not looking for value, just thought I’d share and see if anyone knows any more history, or thoughts.
Cheers,
James

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flynwill

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"Architect of the Capital, Electronics Engineering Division"... So whatever it is, it was likely made in small quantities probably using an off-the-shelf simplex movement as the basis. From the overall construction techniques and appearance it is no older than the mid 1960s, and more likely 1970s. If you can get a close-up picture of the area of the PCB on the left such that we can read the labels on the integrated circuits we might be able to date it more precisely.

I see 6 copies of what look like tuned receiver circuits that likely translate carrier pules of various frequencies on the mains into contact closures.
 

Jmeechie

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Thanks for the info on the clock flynwill. Goes to show some people can’t function searching the Internet! I was going at it the wrong way!
I’m going to message the owner and see if he can send a picture of the circuit board. I’m presuming it’s the board with 7 black rectangles?
 

flynwill

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Yep that would be the area of interest. Integrated circuits of the era had date codes of the form YYWW YY being the last two digits of the year and WW being the week. Also the part number (and the type of logic circuits) will also give a clue as to the date.
 

flynwill

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The circuits are 4000 series CMOS, Low power and tolerant of a wide range of power supply voltage, so good for this sort of applications. I'm pretty sure the date codes are 1984-1986 -- and I note the PCB itself has the code 8817 which might mean it was assembled in 1988. The web page I linked indicates that this system was in use until the early 2000s, so that would fit as well.

If you choose to buy it I would carefully inspect the electronics before applying power. In particular inspect the electrolytic capacitors, any showing any signs of bulging or distress should be replaced. 30 year old capacitors tend to fail with disastrous consequences.
 
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Jmeechie

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Thanks for all the info flynwill. If I do pick it up, I certainly will inspect all the circuits and capacitors before placing it in service. I’m thinking I’d see if I could bypass everything and hopefully just run the Syncron motor on it’s own.
Cheers,
James
 
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