Compatibility of Automatic Electric Model 40 phones with 555 switchboard

[martyspaulding]

Hello all.

I am planning a system using a 555 cordboard I recently purchased. I plan about a dozen extensions.

Using it in an old Inn property in Manistee MI.

I have located some Automatic Electric Model AE-40 phones ... and I'm wondering if anyone is certain if they'll interface properly.

They're 3 wire and all have ringers.

Any odd things I might need to do to make them work ?

[AE_Collector]

The phones will be just fine with the 555. But, you need to check the ringers in the AE40's as they could be a combination of different frequencies and SL ringers. If you can choose the phones you get open them up to check the ringers. You need them all to be the same and preferably all Straight Line ringers.

You will also have to connect them so that the ringers are wired across the line (Bridged). You will get help with that here.

I sold my original 555 board and a bunch of 40's to be used in a bed and breakfast.

Terry

[martyspaulding]

They're being purchased from an assortment of sources (on eBay) so it's unlikely they'll be the same.

How critical is that ? Is it that they'll just ring at different "sounds" because of differences ? Or won't some work at all ? I'm uncertain why they'd need to be identical. Can you explain that ?

Sounds like it might be a real difficult thing to find a dozen that match ... 

[unbeldi]

They're being purchased from an assortment of sources (on eBay) so it's unlikely they'll be the same.

How critical is that ? Is it that they'll just ring at different "sounds" because of differences ? Or won't some work at all ? I'm uncertain why they'd need to be identical. Can you explain that ?

Sounds like it might be a real difficult thing to find a dozen that match ...

It used to be common practice to connect more than one subscriber station to a single telephone line. Such a line was called a "party line".  On party lines the need arose to signal (ring) an individual party without disturbing any others.   One method for this was to design the ringers in such a way that a ringer would only respond to one specific (within a very narrow range) frequency of alternating current.  This made it possible to selectively ring stations by using four or five differently tuned frequency ringers on the line by sending ringing current of different frequencies out to the line.  It is very common to find telephone sets with such frequency ringers.  However, party lines where almost never used for business applications, in which a PBX was used.  Each PBX station used a private pair of wires to the PBX and all ringers were the same.  Typically they all ring at a range between 20 and 30 hertz.  This is called a straight-line ringer, and it is the type that is still used on today's lines.

So, for your PBX you want telephones with straight-line ringers.

[martyspaulding]

Gotcha.

Well hopefully they're all standard, non-party line units. Given that they're AE and not WE, I think it's more probable that they were either commercially installed PBX or other custom units ...

I'd imagine most of the party line folks used what Ma Bell sent them ... which was their own hardware. I guess I'll, find out by process of elimination.

Thanks for the explanation. Makes perfect sense.

[unbeldi]

Party lines were commonly used in Bell territories as well as in independent areas.   The Bell System actually used frequency ringing only until the 1920s, and they did not invest in improvements of frequency-selective systems at all after the 1910s.  They used other methods of selective ringing.  It was the independents that used it until just a few decades ago, and therefore the chance to get a frequency ringer on AE telephones is very high.

[martyspaulding]

Well crud.

Okay. So how can I tell at a glance if a phone is straight line or frequency selective ? And is there a way to correct that issue without having to go through the buy-and-resell process ? Any modification to a filter or component ? Or is it the bell windings themselves ?

[AE_Collector]

No easy modifications or adapters. If you get a frequency ringer the phone will work but won't ring. You need to get phones with Straight Line ringers in them.

Independent telcos used AE equipment (and other brands) and independent companies likely had many more party lines and larger party lines than Bell had. Thus, as Unbeldi said, you are going to have numerous frequency ringers in you phones if you just buy a dozen AE40's.

A good picture of the ringer will quickly tell if it is SL or a frequency ringer. If you don't get pictures, don't buy it! Markings in the base will tell what ringer was originally in it but the ringer may have been changed as party lines were reconfigured.

Terry

[jsowers]

Some ringer identification tips..

AE straight line ringers will usually have SL on the label, if present, and a bias spring near the clapper. The clapper will be permanently affixed to the stem without a setscrew. The clapper will also be on the small side and at the very tip of the stem. Some early ones looked like a hammer or a capsule shape. The SL ringer's clapper will move freely with little effort in a pivoting motion between the bells and I remember them being much nicer to the ears than any of the frequency ringers, which were harsh.

AE frequency ringers will usually have the frequency listed on the label, as in ~33 or ~66 and their clapper mechanisms will be stiffer. Some will have thicker clappers that look like brass cylinders and other metal pieces are attached to tune the ringer for that frequency. They almost always have setscrews in the clapper so it can be adjusted for the frequency. They don't have bias springs.

Two pictures I got from another thread and annotated are posted below FYI. The first shows the difference between the armature of a straight line ringer and a frequency ringer.

The second shows a bias spring--a hallmark of a straight line ringer.

Straight line ringers in AE40s and 50s didn't have an adjustment wheel, like the AE80s did. As Terry said, you stand a very good chance of finding a frequency ringer inside an AE40. It was simply because back then about half the people using an independent Telco had party lines. We didn't have a private line until about 1988, when the phone company did away with party lines.

I'm sure others will have more tips for identifying them. Or you can ask kleptomaniac Claude Cooper and his clean copper clappers.    One of my favorite Tonight Show sketches.

https://www.youtube.com/watch?v=sKGtb1t9iVw

[martyspaulding]

Thanks guys. A learning curve going on here.

Is it possible to reset the frequency of a variable unit so that it operates as a fixed ringer ? Or are they just simply never going to ring on standard 20-30 hz signal ?

 

[AE_Collector]

Some have had some luck with detuning ringers of certain frequencies to the point where they can get a bit of a ring out of them. But not generally the way they should ring. AE40's with SL ringers aren't highly difficult to find, there are lots of them out there. Most likely well over half the 40's you would stumble on have SL ringers in them already. We just want you to know how to avoid the frequency ringers to save yourself the headache since you want to be able to use the phones and have them ring.

Terry

[martyspaulding]

I think I'm clear on the difference, and how to tell them apart now.

Thanks, guys.

I'm sure I'll have more questions as I muddle through this. Once upon a time I had a FCC Second Class radiotelephone license and am currently Ham Technician class. So I'm fairly literate in the electronic discussions. Just theory on how things were done sometimes is outside my bailiwick. I've had a party line (once) but I guess I never gave a thought to the fact that which one rang was phone dependent ... I always assumed it was configured solely at the other end. I do remember that a neighbors phone and ours would sometimes (but not always) ring for each others calls. Such was the 70's.


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