Duplex Electric Company Burglar Alarm System

[Dave Coatsworth]

This is a "Local Burglar Alarm System" manufactured by the Duplex Electric Company. The serial number on the Illinois movement that drives it places its manufacture in 1924. It is driven by a 15 Jewel Illinois movement. A rather large mainspring (see below) allows it to run for 120 hours so that it can run unattended over a weekend that may include a bank holiday on a Friday or Monday. The system uses dry cells for electrical power. (One of these days, I hope to get all of the electrical system working. The Illinois watch movement and the Seth Thomas movement that times the alarm are currently working.)

The case is 24 inches high by 18 inches wide. Depth is 13 inches. It weighs about 80 pounds. (The backboard that the instruments and switches are mounted to is a 1 inch thick slab of marble!)



Upper name plate...



Bottom name plate. Patent dates run from 1910 to 1916.



An inside view of the center of the control panel. The dial in the lower middle allows the bank to set the time that the alarm will run in the case of a break-in. Up to one hour is possible. The timer movement is in the upper center. The main electrical switch is in the upper right. The "Alarm Test" pushbutton in the upper left allows the alarm to be tested without actually setting off the alarm. There is one amp meter for "dry" batteries and one for "wet" batteries.



Top set of knife switches allowing various functions to be set. Note the "Hold Up" switch on the right!



The main switch...



One of the amp meters...



The case opens like a clamshell exposing the wiring on the back of the marble slab and the alarm timer box.



A close-up of the wiring...



The alarm timer box. Inside this box is a Seth Thomas #10 clock movement. When triggered, it runs for the amount of time previously set on the front dial and allows power to go to the alarm.



The "heart" of the system. The winding square is just below the dial. It runs for up to 120 hours as indicated on the dial.



The Illinois 15 Jewel movement. In the place of the mainspring barrel, there is a heavy steel gear which engages the large brass mainspring gear (see movement housing photos below).



Pillar plate...



A mainspring that's just a bit bigger than your average watch mainspring. It sits below the movement. (See the movement block photo below.) The spring is so powerful that the Illinois movement will self-start with only 1/4 turn of the winding key.



The solid steel block that houses the Illinois movement and mainspring.



The front of the movement block showing the electrical contacts. The "Hold to Left While Winding" lever has a piece of insulating material at the top that isolates the electrical contacts while the movement is being wound.



Another view of the movement block. Note that the 4 mounting screws do not screw down tight and have springs around them to isolate the movement from vibration.



Dial close-up...



The plate behind the timer block.



When I bought the timer, this envelope from the Provident Savings Bank and Trust Co. in Cincinnati, Ohio was inside.



It contained these handwritten instructions on setting the alarm system.

[Peter S. Balkan]

I think that's cool Dave. Have you actually had it in operation.

I'm wonder if there was any provision for winding it electrically?

In the watch-shop, there's a Western Union clock that winds itself, from time to time, from a dry-cell battery. It was some time before house current and electrical motors were accurate enough to be run from AC. So... basically, they used mechanical clocks for the timekeeping and used electricity to keep the mainspring wound.

I would also guess that a burglar alarm had to be independent because their would have been no way to secure the AC supply.

p

[Dave Coatsworth]

No self-winding mechanisms on this one. Both the Illinois watch movement and the Seth Thomas #10 clock movement must be wound by hand. The entire thing is in 'unrestored' condition at the moment although both movements are in running condition. Once I restore it, I will add to this story. The first job will be to check the integrity of the wiring and, I hope, to reverse-engineer the electrical schematic. The cloth insulation on the wiring does seem to be in good condition, but I want to make sure there are no hidden shorts before connecting batteries to it. There is no provision for connecting AC - just wet-cell or dry-cell batteries, which makes sense for exactly the reason you state.

[veritas]

This has nothing to do with this topic.
I just dont know where to ask this.
Anyone know if Dave Coatsworth is on vacation?
I have sent several emails in the last few weeks and he had not answered them.
Just wondered if anyone knows.
Thanks.