If there is such a thing as a common Elgin Electronic calibre, it would be the 725. Watches with this calibre, branded "Lord Elgin Electronic", do turn up our favourite auction site from time-to-time. But as to background information on this calibre, once again I'm indebted to John Runciman, FNAWCC of the Chapter 50 Puget Sound, NAWCC for supplying me with images and information and allowing me to publish them on this web site.

On the 725, John says: They supposedly did a limited test marketing in July 1962 in Chicago. Then from a variety of different sources those watches were all destroyed. The references for the destruction are very reliable but it still leaves us with unanswered questions. The service manual was printed in two versions one for one battery and one for two batteries printed in 1961. In 1962 the stockholders report they show a picture of a different Elgin electronic hinting it's going to be out soon. Then also on February 7, 1963 a rather interesting letter* from Dr.C N Challacombe who at that time was the manager of R&D and product design watches. Unfortunately like all the letters that he's done he's answering somebody but we don't know who it is. This particular letter the wording is somewhat strange in that he says that “the watch is planned to sell”. Which gives the impression to me that it's not out yet. He also gives prices of $89.50 in gold filled and $79.50 in stainless steel. What the ultimate aim of $49.50 retail although he doesn't want to be quoted on that.

*A scan of this letter can be seen on the Literature page.

The 725 and 910 Haul:

It's the first batch of photos that got me started on my Elgin collection. I'd been trying to win an Elgin 725 on eBay for sometime; I hadn't got one of these early movements and it was a bit of a gap in my collection.

On one of the watch forums, someone got in touch and offered me a haul of about 7 or 8 Elgin 725s in various states; some assembled, some dismantled, none running. It was a risk, but a deal was struck and I bought them all.

When they arrived, there was only one Cal. 725, the rest were Cal. 910. Although I'd never heard of an Elgin Cal. 910 before, I wasn't disappointed; the 910 seems to be even rarer than the 725. It was Elgins next evolution of the electronic watch movement but few reached the market place.

Three complete watches; these turned out to be Cal. 910 as well as the majority of the uncased movements.

Looking at the markings revealed most of them to be Cal. 910.

Same white dial on all the watches. All suffer from brown marks due to radium burns where the lumed hands have been left in one position for decades.

Three spare stainles steel cases (style ), 2 battery hatches and a movement ring.

Another photo of the uncased movements together with their movement rings.

The 725 and 910 Calibres:

The research and restoration is underway! First task was to understand the difference between the Cal. 725 and Cal. 910. At first glance, they look the same, but after careful examination, the following differences can be observed (there are probably more):

• 910 has a re-designed, lighter balance but still retains the balance horn of the 725 and the same hacking clip of the 725
• 910 has a re-designed coil with mounting screws at each end; 725 has its two screws on the non-horn end.
• 910 has a re-designed movement plate to support the changed mountings of the coil
• 910 coil has a more prominent horn (similar to Lip R148)
• 910 has two contact wires (similar to Lip R148); 725 has a single contact wire
• 910 has a free-floating diode; 725 has the diode stuck to the coil
• 910 has 14 jewels to the 15 of the 725
• 910 train bridge is reduced around the right hand screw to give additional clearance for new insulated wires

Cal. 725 can be found in both gold and stainless steel case watches. Cal. 910, on the otherhand, has only been found in the stainless steel case.

Cal. 910 is very similar to the LIP R148 movement. This is not surprising bearing in mind that Elgin and LIP worked togther in certain aspects of developing the first electric movement. There is some reference to this partnership in the Literature section.

Left Column: Cal. 725. Middle Column: hybrids?. Right Column: Cal. 910	Group photo of 910 movements.	Left Column: Cal. 725. Middle Column: hybrids?. Right Column: Cal. 910	On the Left: two Cal. 725. Top Right: marked as a Cal. 725 but with Cal. 910 features (coil, balance etc). Bottom Right: Cal. 910	Cal. 725	Cal. 910
Unusual Cal. 725. On this movement, the balance is quite different from a normal Cal. 725 or Cal. 910 balance. Copyright: J. Runciman, FNAWCC	Early Cal. 725 with its Elgin battery. This would have fitted to a case without a battery hatch ;-) Copyright: J. Runciman, FNAWCC

The following are some slightly more detailed photographs of the movements:

Cal. 725 from a case without a battery hatch. The single modern silver oxide battery is being held in place by the clip and a peice of rubber; the latter ensures the battery is pushed up hard against the movement body to complete the +ve side of the circuit. No dial insulator is needed in this configuration and the clip would have originally held two batteries. The movement is running in this photograph.

Close-up of the running balance on a Cal. 725. You can clearly see the glass diode stuck to the side of the coil; on a Cal. 910, this diode is black and free floating.

Cal. 725 with the balance removed. The large vertical purple jewel is known as the Deflecting Jewel and serves to hook the contact wire away from the balance pin on the return swing --- in my view, it is not necessary; the very similar LIP movements did not have this feature. The large slot in the base plate is for adjusting the clearance between the jewel and contact wire (0.0005 inch).

Close-up of the Deflecting Jewel and Contact Wire on a Cal. 725; the Cal. 910 is very similar except there are two contact wires (same as LIP R-148). To complete the circuit to energize the coil, on each anti-clockwise swing of the balance, the wire hits the visible knife edge. The contact wire is made from a platinium-gold alloy and is 0.001 inch in diameter.

Cases, Dials and Batteries:

Cases were either gold or stainless steel. The gold ones come in a variety of styles (see below); some with a battery hatch and some without. The stainless steel cases only seem to be in a single syle and all have a battery hatch. Case style numbers are usually stamped on the inside of the case; serial number are stamped on the inside for stainless steel cases and on the outside for gold cases. In all cases, the movement come out through the crystal.

There seem to be two main dial styles: one for gold cases and one for stainless steel cases. In the case of the latter, the dial was either white or grey with some slight differences: the grey variety has no numerals at the hour markers and has double fluts at 12 oclock. Nearly all my stainless steel case dials show radium burn marks on the dial where the lumed hands have not been moved for decades; sadly, it is impossible to remove these marks. There were also several early prototype dial designs as shown below.

Batteries used were (in chronological order):

1. Elgin battery: Cal. 725 in gold cases with no battery hatch.
2. Two button cell batteries: Cal. 725 in gold cases with no battery hatch.
3. One button cell battery (small): Cal. 725 in gold cases with battery hatch.
4. One button cell battery (large): Cal. 725 and Cal. 910 in stainless steel cases with battery hatch.

In 3) and 4) above, the dials had a half moon shaped piece of plastic glued to their under surface to prevent the -ve terminal of the battery shorting out on the dial surface. In those cases with a hatch, the battery should be placed with the negative terminal towards the dial.

Three gold cases of different designs; the middle lacks a battery hatch and probably took a 725 movement with two batteries. Copyright: J. Runciman, FNAWCC	The same three gold cases but viewed from the front. The middle one showing some unusual milling to the inside of the case and also seems to lack the stem 'O' ring enclosure. The case on the left is the most common of the gold cases. Copyright: J. Runciman, FNAWCC	The most commom Cal. 725 gold case: Style 2051 with battery hatch.	The most commom Cal. 725 gold case: Style 2051 with battery hatch.	The ?only? stainless steel case, used both with Cal. 725 and Cal. 910: Style 2552 with battery hatch.	A Cal. 725 and gold case from the watch with the prototype dial in the next image. This case also has the milling and seems to lack a stem 'O' ring enclosure.
Prototype dial design from the watch in the previous image.	More 725 prototype dial designs for the gold cased watches Copyright: J. Runciman, FNAWCC	Standard Cal. 725 dial design used in the gold cased Elgin Electronics although there is some hand variation when compared with the next photo.	Standard Cal. 725 dial design used in the gold cased Elgin Electronics although there is some hand variation when compared with the previous photo.	Standard Cal. 725 or Cal. 910 grey dial used in the stainless steel cased Elgin Electronics.	Standard Cal. 725 or Cal. 910 white dial used in the stainless steel cased Elgin Electronics.
Some of the 910 dials (from the haul at the top of the page) are not in particulary good shape.	Some of the 910 dials (from the haul at the top of the page) are not in particulary good shape.	Some of the 910 dials (from the haul at the top of the page) are not in particulary good shape.

Restored Watches:

From the collection of parts shown at the beginning of this page, plus the addition of one Cal. 725 in gold case and one Cal. 725 in stainless steel case, I've ended up with the following working watches, all keeping pretty good time. In all cases, the original dials have been used; I picked the best-of-the-bunch but some still show radium burn marks.

• 1 x Cal. 725 in gold case
• 1 x Cal. 725 in stainless steel case
• 3 x Cal. 910 in stainless steel case

Cal. 725 in gold case.	Cal. 725 in gold case.	Cal. 725 in gold case.	1 x Cal. 725 and 3 x Cal. 910...all in stainless steel cases.	1 x Cal. 725 and 3 x Cal. 910...all in stainless steel cases.	1 x Cal. 725 and 3 x Cal. 910...all in stainless steel cases.
1 x Cal. 725 and 3 x Cal. 910...all in stainless steel cases.	1 x Cal. 725 and 3 x Cal. 910...all in stainless steel cases.	1 x Cal. 725 and 3 x Cal. 910...all in stainless steel cases.	Cal. 725 in stainless steel case.	Cal. 725 in stainless steel case.	Cal. 725 in stainless steel case.

It's been an interesting journey and I'm please with the knowledge gained and the watches restored.