Unknown (to me) Stromberg Carlson wall phone

[Smitty]

When I was at the estate sale where I bought the subset that I posted about a few days ago, I also saw a metal wall phone that had no receiver.  The only marking I could see was on the back of the transmitter cup, which identified it as a Stromberg Carlson.  They had priced it at $25.  I didn't buy it because I was unfamiliar with that type phone, it was incomplete, and mostly because I'm a newbie and had no idea if it was worth that or not.  I decided to go back on Sunday, the last day of the sale.  It was still there and they came down to $8.00, so I bought it.  After buying it I started researching to try to identify it, and I think it is the same type phone that Nick in Manitou recently wrote about in his thread titled "Big Load of Parts - What Are They?" (sorry I can't figure out how to insert it as a hyperlink).  Mine appears to be the same as his, except for having a different transmitter cup and having the transmitter and gongs.  Nick believes his is a Model 1130, and the few pictures of that model on the internet make me think he's correct.  Here are some photos.  Please excuse the filthy condition - I have done nothing to clean it.

[19and41]

Looks like there is something good under the dirt.

[Nick in Manitou]

Smitty,

Thanks for posting this.  It sure does look like the same model that I have.  There does not seem to be a lot of information about these easily found on the internet.

I will be watching to see if folks post some information about these!   

Nick

[unbeldi]

I think we can date this from the materials used and the style of some parts, e.g. the transmitter.

In general, steel housings started to appear in the mid 1910s, increasingly displacing wood housings for subscriber sets. WECo lead the change, I believe, so the independents were a little slower and lagging.

Almost simultaneously, the gongs migrated inside, probably because the thin metal had a much lower tendency to absorb sound than a wood enclosure. Yours still has them outside, which is the progression that was typical, same as WECo.

The size of capacitors alone is an indication of time, and these types as shown, are also from the 1910s.  This looks like it is not a ringing capacitor, to block DC from the ringer, but what S-C and other companies called a "Sure-Ring" capacitor, that prevented the line from being unusable when someone left the receiver off-hook.  Yours has a capacitance of 2 µF, which is rather large for just being a ringing capacitor, but just right for preventing shunting the line when off-hook.  However, it is still possible that this set was used for common-battery service, and the capacitor performs a dual-function, just like in WECo 534A subscriber sets, which used 1 µF caps, but it is known that before WW-I their CB sets also used a 2 µF value.

The transmitter appears to have been added perhaps starting in the middle 1930s, when distinct transmitter elements and receiver elements became fashionable.  These were more efficient and didn't require the narrow mouth piece that was common previously to focus the sound onto the diaphragm.  Compare it to those made by AE and of course the even wider bull-dog transmitter by WECo.


So with some measurements on the induction coil, you should be able to determine whether this is a common-battery subscriber set, which I suspect it is.
It should be fairly easy to rewire correctly.   I would look at the diagram for the 1155 Wall Telephone, which is the 1930s version of this, which had the gongs inside of course. The condenser had moved from being on the side of the ringer, to the yoke end of the ringer, increasing the size of the box slightly more, than just as needed for the internal gongs.  Pics attached.  Your transmitter is probably from the late 30 or even 1940s.  What's inside the transmitter cup?

Are there any numbers on the induction coil?

[Smitty]

Thanks for the replies!  Unbeldi, I looked at the induction coil and could not see any markings anywhere on it.  Only after I put it all back together did I realize that I hadn't taken a photo of it.  I am not at all a technically-oriented person, so this is probably a dumb beginner's question, but by measurements do you mean just the physical dimensions? If so, the coil (excluding the blocks on the ends) is 3.5 inches long and 1 inch in diameter.

I did manage to open up the transmitter cup and take the picture below.  Does this tell anything about the date of the transmitter?

[unbeldi]

Thanks for the replies!  Unbeldi, I looked at the induction coil and could not see any markings anywhere on it.  Only after I put it all back together did I realize that I hadn't taken a photo of it.  I am not at all a technically-oriented person, so this is probably a dumb beginner's question, but by measurements do you mean just the physical dimensions? If so, the coil (excluding the blocks on the ends) is 3.5 inches long and 1 inch in diameter.

I did manage to open up the transmitter cup and take the picture below.  Does this tell anything about the date of the transmitter?

With the part number  P-26791 on that transmitter assembly, I found a reference in a catalog dated 1942, that shows exactly that part being used on the 1155 wall set.
So, the estimate of late 1930s to 1940s is correct.
The transmitter itself is a Type 20 transmitter.  I'll see whether I can found some more info on it.

With 'measurement' I mean to measure the electrical resistance of the coils.  The induction coil has two windings of wire, called the primary and the secondary winding, just like a transformer.  The primary winding connects to the transmitter which is the source of the speech signal, whence 'primary'.
In local-battery telephones the electrical resistance of the primary winding is very low, typically just a few ohms, while in a common battery telephone, which is powered from the line, the resistance is much higher, perhaps even 10 times as much.  This doesn't always work out that way, but is a guide line.

PS: I don't have any other info on that transmitter.  It was also used on the desk stands that were still listed in the 1942 catalog.

[Smitty]

With 'measurement' I mean to measure the electrical resistance of the coils.

I was afraid of that!  Now I'll have to learn a new skill, but that's a good thing!  Thanks for confirming the date on the transmitter.  One of the few photos of the model 1130 I could find was in a catalog printed in 1919 to promote the products that were produced in Rochester.  It's at http://www.libraryweb.org/~digitized/books/Book_of_Industrial_Rochester.pdf . The Stromberg Carlson products are on page 58 (of 97 total).  This 1919 date would confirm your comment that the rest of the phone is from the 1910s.  By the way, for anyone who has a little spare time, this catalog makes for some interesting browsing.

P.S. - I just noticed that the model 1130 in the S-C ad is shown under the heading "Common Battery Telephone Equipment."

[unbeldi]

I was afraid of that!  Now I'll have to learn a new skill, but that's a good thing!  Thanks for confirming the date on the transmitter.  One of the few photos of the model 1130 I could find was in a catalog printed in 1919 to promote the products that were produced in Rochester.  It's at http://www.libraryweb.org/~digitized/books/Book_of_Industrial_Rochester.pdf . The Stromberg Carlson products are on page 58 (of 97 total).  This 1919 date would confirm your comment that the rest of the phone is from the 1910s.  By the way, for anyone who has a little spare time, this catalog makes for some interesting browsing.

Good find. It's the closest match so far, and I would think it is the right one.  That box seems to be a metal housing, although it is hard to tell.

P.S. - I just noticed that the model 1130 in the S-C ad is shown under the heading "Common Battery Telephone Equipment."

I was just about to tell you that too.  I looked up that book and indeed interesting stuff.  The library also has another one from 1934, but S-C only has some radio or audio system in there.

For posterity here is a copy of the CB sets.  The 986 desk stand seems to have been created about that time too, not before 1917 or 18, and was made into the 1920s, I have magazine ads for that dated 1921.