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Stromberg-Carlson 1212ADH

Started by Ed Morris, August 04, 2017, 03:28:40 PM

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Alex G. Bell

Quote from: Ed Morris on August 06, 2017, 10:14:17 PM
I found a working 65-C ringer, but I couldn't find any data on it.  I assume it's an SC ringer as it looks exactly like my 59H.  It may possibly be a straight-line ringer, but I'm not sure.  Anyone familiar with it?
Inspecting the way the armature is attached would immediately tell you whether it is SL or not.  Any SL ringer will have a freely pivoting armature with a bias spring to deflect it to one side.  A frequency ringer must be stiffly springy and not pivoting.   

Photos of the front of the ringer may help others to identify which it is if you can't based on this description.

Ed Morris

I think this ringer was used in the SC model 1248, so it may not work in the 1212.  I think I need to find a 57A, 59A or 61A ringer.

Ed

Alex G. Bell

Quote from: Ed Morris on August 06, 2017, 11:27:12 PM
I think this ringer was used in the SC model 1248, so it may not work in the 1212.  I think I need to find a 57A, 59A or 61A ringer.
The leads are in the way of seeing the armature pivot but it looks like it might be a pointed screw and lock nut.  The angle is not good for seeing the things which need to be and the image is a bit blurry.  But I think it might be SL.

Does it fit the 1212 and mount by the existing holes?  Why do you think it might not work?

Ed Morris

I don't have the 65-C in my possession, but certainly looks like the 59-H from what I can see in the photos.  I don't know if it would work because the model 1248 is a magneto powered desk set, and I don't know if it would work in the 1212.
Ed

Alex G. Bell

Quote from: Ed Morris on August 07, 2017, 07:56:21 AM
I don't have the 65-C in my possession, but certainly looks like the 59-H from what I can see in the photos.  I don't know if it would work because the model 1248 is a magneto powered desk set, and I don't know if it would work in the 1212.
The fact that it's from a magneto 1248 set does not necessarily mean it won't work in a CB 1212.  The primary concern is whether it will fit and mount with the existing holes.

Ed Morris

I'm taking a chance on it.  It should be here in a few days.  I will post an update.   
Ed

unbeldi

#21
The 65-C was typically used in 1248-WI, 1258-WI magneto telephones and the 1268-WI desk set box for straight-line, polarized ringing, without bias spring.  They made three varieties of these, -A, -C, and -F, each with a different set of coils, presumably with three different impedances, I think 2040 Ω, 3100 Ω, 4850 Ω, resp.

I think you will be disappointed with it on a common battery line, especially during dialing. For best straight-line ringing today, you probably want a biased high-impedance ringer, such as a 61-S, or 65-S, but hard to find. Usually when someone has adapted these sets, they mount more modern single-gong miniature ringers from the 1970s, such as a SC-P1A or other ITT ringers.

The 57 and 59 series don't have an -A suffix. They are both frequency-tuned ringers, -F through -R.
The corresponding straight-line ringers are 55-A and 56-A types (unbiased and biased), or the 61-A (low impedance).


Ed Morris

Excellent information, unbeldi--thanks!  I will keep searching.  One of the better choices will show up eventually.
Ed

Alex G. Bell

Given the difficulty of finding the correct ringer perhaps he can add a bias spring to this one.  It's certainly more adaptable to the purpose than any frequency ringer would be.

3100 Ω is not a very low resistance (and impedance).  Most 534, 554, 584, 634 and 684 subsets have 1000 Ω ringers.  Even a 500 set is only 3650 Ω.  So the impedance is adequate.
Quote from: unbeldi on August 07, 2017, 10:08:12 AM
The 65-C was typically used in 1248-WI, 1258-WI magneto telephones and the 1268-WI desk set box for straight-line, polarized ringing, without bias spring.  They made three varieties of these, -A, -C, and -F, each with a different set of coils, presumably with three different impedances, I think 2040 Ω, 3100 Ω, 4850 Ω, resp.

I think you will be disappointed with it on a common battery line, especially during dialing. For best straight-line ringing today, you probably want a biased high-impedance ringer, such as a 61-S, or 65-S, but hard to find. Usually when someone has adapted these sets, they mount more modern single-gong miniature ringers from the 1970s, such as a SC-P1A or other ITT ringers.

The 57 and 59 series don't have an -A suffix. They are both frequency-tuned ringers, -F through -R.
The corresponding straight-line ringers are 55-A and 56-A types (unbiased and biased), or the 61-A (low impedance).

unbeldi

#24
Quote from: Alex G. Bell on August 07, 2017, 01:31:20 PM
Given the difficulty of finding the correct ringer perhaps he can add a bias spring to this one.  It's certainly more adaptable to the purpose than any frequency ringer would be.

3100 Ω is not a very low resistance (and impedance).  Most 534, 554, 584, 634 and 684 subsets have 1000 Ω ringers.  Even a 500 set is only 3650 Ω.  So the impedance is adequate.

I did not state that it was "very low resistance".

Ringer impedance cannot readily be inferred from these DC resistance values, other than qualitatively stating that the impedance generally increases with resistance, although that is not always true, as in the following example.

For example, a WECo #8A ringer with a DC resistance of 1400 Ω has an impedance of over 4 kΩ at 20 Hz for its complete ringing bridge with capacitor, while a B1A ringer with over 3x  the DC resistance (4600 Ω) has an impedance only twice as high.  A C4A ringing bridge with only 3650 Ω DC of the C4A, however, has an impedance slight larger than that of the B1A at the same frequency.


Alex G. Bell

#25
Quote from: unbeldi on August 07, 2017, 03:03:20 PM
I did not state that it was "very low resistance".
Didn't say you did, just that it's high enough to not be a concern, so if it fits mechanically and if it is feasible to add a bias spring that might be the most practical solution at least for now, since they are hard to find and he bought it.

Didn't think about it until now but I have a 1248WI here containing a 65-C.  I can inspect it to see whether adding a bias spring would be easy.

unbeldi

#26
Here is a No. 61-A ringer in a 1243 set.

Notice the biasing spring on the left side of the ringer.

Alex G. Bell

Quote from: Ed Morris on August 06, 2017, 11:27:12 PM
I think this ringer was used in the SC model 1248, so it may not work in the 1212.  I think I need to find a 57A, 59A or 61A ringer.
What is the code of the ringer in the photo shown in Reply #17?  Is it the same as the 65-C shown in #15?

Alex G. Bell

Quote from: unbeldi on August 07, 2017, 05:11:02 PM
Here is a No. 61-A ringer in a 1243 set.

Notice the biasing spring on the left side of the ringer.
I can't see how the armature end is attached.  I've seen armatures which were drilled in the edge with the wire loop force-fit into the hole.  So if the 65-C physically fits into the 1212 and mounts with the same holes it's probably feasible to improvise a similar attachment.  The tension screw adjustment would be difficult to duplicate but simpler less adjustable methods should be satisfactory.

The specialty hardware drawers at places like Home Depot, Lowes and Ace hardware stores contain some surprisingly exotic things these days, like an assortment of #0-80 machine screws and nuts and springs.  It may be possible to find a suitable low force spring in one of these places.

Ed Morris

The ringer in post #17 is the same ringer shown in #15.  I have a spring assortment from Harbor Freight, so I probably have one that may be suitable. I may need a couple good close up photos of the 61-A ringer to see how I might fabricate one if possible.
Ed