January 2015 Arduino-based Master Clock

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IBMJunkman
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January 2015 Arduino-based Master Clock

Post by IBMJunkman » Mon Jan 05, 2015 9:21 am

The article is great for the old IBM clocks running on 24VDC. Now we need an article on building a controller that injects signals onto the AC line for the clock shown below. I can't put my finger on the info as to what frequency the signals need to be. I have a book that shows the old tube circuit that does the injection.
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AviatorFJ
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Re: January 2015 Arduino-based Master Clock

Post by AviatorFJ » Mon Jan 05, 2015 9:29 am

I second that. I have a collection of Simplex/IBM clocks running 3-wire off a 6400 master and would love to figure out how to overlay the (approx) 3500 Hz carrier onto a 115VAC household circuit.

The idea of plugging any clock into any circuit without hard wiring is beyond a dream.

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Lenp
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Re: January 2015 Arduino-based Master Clock

Post by Lenp » Thu Jan 08, 2015 9:02 am

I worked on these systems years ago for a large school district. Yes many of them used a transmitter with parallel push pull 6L6's as outputs. Some of the newer systems had a motor generator unit with several generators, one for each frequency.
The master clock started the motor and keyed the selected generator through an exciter winding. The output was
coupled to the line with capacitors. Capacitors were also used for coupling across phases, or transformer windings.
We had a rather crude signal meter that measured the voltage of the control signals on the power line.

The early receivers, as shown in the picture, used tuned coils and a thyratron but newer receivers were all solid state.
I don't know if Simplex ever produced a solid state transmitter. I would think that other data transmission techniques has made these systems
obsolete, but, parts are still available from American Time and Signal.

They also made a coded bell system that was used on both the wired and wireless systems. It had a 1 RPM motor with a cup like
affair that relied on getting a pulse to start the motor and cup that rotated. Another pulse sometime within a 1 minute period
was needed to 'capture' an arm that operated the signal contacts at the end of the rotation. If the timing did not match the
cup settings, the contacts did not close. The bell time would need to be set on the master clock 1 minute ahead of the scheduled
bell to allow for the motor and cup to cycle. The same scheme was used to control contractors for HVAC control.

As a footnote, I have a quantity of used Italian Flip-Flap style clocks, branded ICON 30. They are 24 VDC impulse clocks with hourly correction,
and should work on the clock system described in the original article. Here is a YouTube (not mine) on the same clock. https://www.youtube.com/watch?v=2IRkG5m9b_Y
PM me if you are interested in these
Len

“To invent, you need a good imagination and a big pile of junk.” (T. Edison)
"I must be on the way to success since I already have the junk". (Me)

marc4g
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Re: January 2015 Arduino-based Master Clock

Post by marc4g » Tue Jan 20, 2015 11:55 am

According to my 1953 Sylvania Tube manual, the 6L6 is a Power Pentode.

Are there any schematics actually showing how the 6L6 is used?

The attached schematic seems to show a gas filed full wave rectifier of some type. (Similar to a 6X6 ?)

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Lenp
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Re: January 2015 Arduino-based Master Clock

Post by Lenp » Tue Jan 20, 2015 1:02 pm

Hi Marc,
The 6L6's were used in the transmitter, not, the receiver. They were the output tubes.
The receiver did use the gas filled thyratron.
Len

“To invent, you need a good imagination and a big pile of junk.” (T. Edison)
"I must be on the way to success since I already have the junk". (Me)

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Re: January 2015 Arduino-based Master Clock

Post by marc4g » Tue Jan 20, 2015 5:50 pm

Len:

Wow,

Do you happen to know the PN for these old time 'SCRs' ?

Do you have any more details on how the system worked?

The detail on the attachment was too pixelated for me to make out a lot of the detail in the schematic.

Before I retired, I worked at the University of Washington in Seattle as a control tech. I worked mostly on the fire alarm systems (Simplex), but also we maintained the clock and class bell system for the campus. (>620 Acres) and the Hospital Complex (Used to have the longest hallway in the world (guinness).

The hospital had a clock system that sounds like the one discussed in this thread, but it was replaced before I started working there with a Simplex system.

Marc

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Re: January 2015 Arduino-based Master Clock

Post by marc4g » Tue Jan 20, 2015 10:49 pm

These clocks are starting to make sense to me now.

They look like older versions of the Simplex Analog Clock with the solenoid control (red wire).

It looks like they are still around. Instead of a control input on the 'red' wire. (The other 2 are 120v (Black) and Neutral (White)) you inject a signal of 2Khz to 19Khz into the 120v line for the standard time 2 sec every 59th min, 8 seconds for the hourly correction, and 14 seconds for the 12 hour reset.

I do not know exactly you go about injecting the control signal into the 120v line and what the code aspects are, but I imagine that in a 60Hz world, injecting 2-19Khz signal would be a fairly easy thing to do. (Kinda like X10?)

See model 45012 on the site.
http://www.kennyco.net/PDF's/4000/CCT%2 ... tion-4.pdf
And here is an article from a 1960 issue of Popular Electronics
http://www.rfcafe.com/references/popula ... ronics.htm

Marc

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Lenp
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Re: January 2015 Arduino-based Master Clock

Post by Lenp » Wed Jan 21, 2015 6:13 am

Ah yes. Carl & Jerry, old friends indeed!
Yes the carrier control signal fires the thyratron that operates the correction solenoid and the rest is the same as a wired clock. We used to add the receiver bracket assembly to the standard clock when needed.

If I remember correctly for clock control it was a single burst of tone for about 2 seconds long that operated the correction solenoids. Once the cam latched the correction process continued. As mentioned previously the carrier controlled bells required a timed sequence of two signals to operate. The first started all the code motors and the second, with critical timing l
atched an arm so the bell would ring at the end of the cycle. Even those could be controlled in a fully wired system with the right master clock setup. American Time and Signal has more lnformation.
I can check with some past associates to see if anything remains from years long ago.
Len

“To invent, you need a good imagination and a big pile of junk.” (T. Edison)
"I must be on the way to success since I already have the junk". (Me)

IBMJunkman
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Re: January 2015 Arduino-based Master Clock

Post by IBMJunkman » Wed Jan 21, 2015 11:45 am

Large images of the clock backs.

http://www.myimagecollection.com/clocks/

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Lenp
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Re: January 2015 Arduino-based Master Clock

Post by Lenp » Wed Jan 21, 2015 1:37 pm

In a nutshell the coil and cap across the power line is a series resonant circuit and the other coil is parallel resonant at the signal frequency. The bendable bracket allows coupling changes between the coils. When both coils are in resonance coil 2 developed a voltage that triggers the thyratron, which conducts, and energized the correction solenoid.
See... Microprocessors are not always needed! :shock:
Len

“To invent, you need a good imagination and a big pile of junk.” (T. Edison)
"I must be on the way to success since I already have the junk". (Me)

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Re: January 2015 Arduino-based Master Clock

Post by marc4g » Wed Jan 21, 2015 3:23 pm

I have a 1940 RCA tube manual and one of the 1st tubes in the thing is a 0A4-G gas triode. Looks like it basically a neon bulb with a control grid! The idea was to bring the 'starter anode' just up to the 'required breakdown' voltage. A voltage divider of 10k/(15k+10K) *117vac would give 46Vrms (66v Pk). Looking at the "Typical Breakdown Characteristics" it looks like the breakdown was a little over 80v.
I did notice that the "Outline' drawing was much larger for this tube that what was in the one in the clock.
I have not been able to find the one installed in the picture of the clock (miniature) on the 'web' though.



I did find an application for the OA4-G in the June 1940 issue of this publication:

http://www.americanradiohistory.com/Arc ... 940-06.pdf


(I guess back in the '40's the 'official power voltage was 117 rather than 120... probably a story here..)

I would think that you could retrofit one of these things with an optically coupled SCR driver. Or just use a modern sync pulse of 120v half wave rectified and attach to clutch solenoid.
d

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Re: January 2015 Arduino-based Master Clock

Post by marc4g » Wed Jan 21, 2015 3:26 pm

IBMJunkman wrote:Large images of the clock backs.

http://www.myimagecollection.com/clocks/
Thanks, this image makes it all clear!

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