thatonejohn wrote:I picked it up, sitting in the garage currently. Haven't had time to look at the C250 database to figure out what numbers and such to grab off of it yet. It's in pretty rough shape (water damage, and no veneer on the back), but the motor appears good, and the reproducer is decent, played the record it came with. Still have to figure out how the Duncan stop is supposed to be wired, and how it functions.
Hello thatonejohn,
I wrote an extensive article on the Edison
Electric Automatic Stop (AKA the "Duncan Stop") for the Antique Phonograph Society; you can read it on their website, here:
http://www.antiquephono.org/edison-auto ... tric-stop/.
I explain the history and theory behind its function, and with photographs of the various components of the system I explain how the system was designed to work.
Originally, all of the circuit contact points were nicely gold plated, and as is with all electrical circuits,
corrosion is the enemy, so you need to make sure all the contact points are clean. Also, a specifically modified
EAS Reproducer is necessary, so make sure you have the right one.
In my article, I show the proper EAS Reproducer, break it down into it's individual electrical parts, and explain how it was designed to functioned.
The battery that was most likely used (the literature was not as specific as we might like) was the "No.6 Ignition Cell" which would have put out around 1.5V, and it's amperage probably varied greatly with the manufacturer. It's my understanding that some folks have successfully used variable DC output power supplies like you might find used for small scale train setups of the appropriate output voltage -- even so-called "wall-warts" could be used. The trouble with these would be that pesky cord.

Alternatively, 4 "D" cells in a
parallel configuration, might provide enough current to energize the EAS, to make it reliably function.
After cleaning and checking the components, you would likely need to do a little experimentation with the actual voltage and amperage to get the system to function properly. My assumption is that 2-4VDC at about 1-2 amps should be more than sufficient. I've gotten the solenoid to close with a single standard modern "D" cell, but I haven't tried this "in circuit" installed on a Phonograph, and I doubt it would provide enough current to reliably function.
I'd love to have a rational detailed discussion on the electric automatic stop observed, to see what works in the real world.
If you wish to restore yours to working order, my guide can certainly help you on your way.
Since the writing of the article, I've taken several improved photos of the Reproducer electrical contact points, but I haven't submitted them to George Paul yet to "upgrade" the article on the website. Below are a couple of the photos of the reproducer from the article along with three new photos.
If you haven't recently been to the
http://www.antiquephono.org/ webpage, I urge you to check it out! It's a great source of information that has grown quickly with new and highly informative articles appearing frequently.
Oh, and if you haven't already; become a member of the
Antique Phonograph Society, the dues are a small price to pay for the volume
and value of information the group provides us with.
Best,
Fran

- Rear of reproducer2.JPG (291.32 KiB) Viewed 2624 times

- Limit pin and loop - end play2.JPG (365.52 KiB) Viewed 2626 times

- Limit pin and loop - end play.JPG (353.52 KiB) Viewed 2626 times