Author Topic: Location of dial fingerstop  (Read 2139 times)

Offline Bill

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Location of dial fingerstop
« on: November 19, 2011, 12:26:52 PM »
Most WE dials have the fingerstop at about 4 o'clock. Is there one with a fingerstop at 5 o'clock? Thanks

Bill

Offline dsk

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Re: Location of dial fingerstop
« Reply #1 on: November 19, 2011, 01:58:42 PM »
 :) My Siemens modell 1936:
the Norwegian made phones has the fingerstop nearly half past five. ;D
]   

dsk
« Last Edit: September 26, 2017, 02:04:43 PM by dsk »

Offline dsk

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Re: Location of dial fingerstop
« Reply #2 on: November 19, 2011, 02:05:42 PM »
Another interesting thing is the location of the 0 and the angel between the holes. WE AE Siemens EB LME they are all different.

dsk

Offline Phonesrfun

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Re: Location of dial fingerstop
« Reply #3 on: November 19, 2011, 07:57:58 PM »
Most WE dials have the fingerstop at about 4 o'clock. Is there one with a fingerstop at 5 o'clock? Thanks

Bill

All WE dials are in approximately the 4 O'Clock position.  All the independant dials except for ITT went with the 5 O'clock position.  There is actually a valid technical reason for the independants having the finger stop in this position.  Does anyone know why?
-Bill G

Offline AE_Collector

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Re: Location of dial fingerstop
« Reply #4 on: November 19, 2011, 08:36:12 PM »
On some dialss it gives a longer "Inter-Digital Pause" which was a good thing with Strowger switching which more of the Independant companies used where as the Bell system used a lot more Panel and Crossbar which don't need extra "Inter-digital Pause".

Is that what you were going for Bill?

Terry

Offline Phonesrfun

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Re: Location of dial fingerstop
« Reply #5 on: November 19, 2011, 08:43:12 PM »
On some dialss it gives a longer "Inter-Digital Pause" which was a good thing with Strowger switching which more of the Independant companies used where as the Bell system used a lot more Panel and Crossbar which don't need extra "Inter-digital Pause".

Is that what you were going for Bill?

Terry

Bingo!  

For everyone else:  If you look carefully at an AE dial, there is a wider angle between the gap between the 1 and zero holes (compared to the WE),  Just enough inter-digital delay to let the equipment keep up with the faster people.
« Last Edit: November 19, 2011, 08:46:36 PM by Phonesrfun »
-Bill G

Offline AE_Collector

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Re: Location of dial fingerstop
« Reply #6 on: November 19, 2011, 09:06:44 PM »
Just enough inter-digital delay to let the equipment keep up with the faster people.

And here the word digital has similar meaning to when it is used in reference to Prostate Exams IE: nothing to do with 1's and 0's! (sorry!)

Terry

Offline Phonesrfun

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Re: Location of dial fingerstop
« Reply #7 on: November 19, 2011, 09:10:24 PM »
Yikes.  I just had an exam.  Not fun.  (Lets not go there)
-Bill G

Offline dsk

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Re: Location of dial fingerstop
« Reply #8 on: November 20, 2011, 02:39:32 AM »
If you  Google  w48 wahlscheiben you will see the Germans should have real trouble there.    ;D

dsk

Offline GG

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Re: Location of dial fingerstop
« Reply #9 on: November 20, 2011, 04:10:54 AM »


The key factor here is not the location of the fingerstop but the number of finger-holes that would fit into the solid portion of the dial fingerwheel.

Every finger hole represents the distance that the fingerwheel rotates in the return direction to produce a single dial pulse (equivalent in time to 100 milliseconds). 

WE dial fingerwheels have space in the solid portion for two more finger holes: thus their interdigital pause (pause between digits) is at minimum the equivalent of two dial pulses (200 mSec) plus the time it takes for the subscriber to stick his/her finger in the hole for the next digit and pull it around to the fingerstop. 

Other manufacturers didn't make assumptions about the time taken for the subscriber to pull the next digit to the fingerstop: AE, Kellogg, and SC all have enough space on the solid side of the fingerwheel to accommodate three holes, thus an interdigital pause that's the equivalent of three dial pulses (300 mSec), just to be sure there was a long enough pause.  The same case obtains for your EB/Ericsson 1931 desk set (the one that got Western Electric on track to design the 302), and all subsequent Ericsson dials.

However, on your 1936 Siemens phone, the solid space is equivalent to two more holes between the hole for the digit 1 and the fingerstop (200 mSec).  More interestingly, the position of the fingerstop is such that the actual "blank space" between it and the digit 1 hole, is equivalent to about 1-1/4 additional holes (140 mSec). 

A similar case obtains for American 2-1/2" dials such as the AE "Mercedes" dial.  The AE "Sunburst" dial is even more extreme in this regard: there is only ONE space there (100 mSec), and of course that space has a hole in it per the design of that dial:

http://www.classicrotaryphones.com/forum/index.php?topic=5465.0

At the other end of the spectrum, the dials used on the German W-48 and subsequent models, and on GPO telephones, have space for FOUR additional holes in the solid side of the fingerwheel.  The positions of the fingerstops on both those German and English phones, are such as to provide an interdigital pause equivalent in duration to four dial pulses (400 mSec).  Many other foreign dials have a similar construction, regardless of where the fingerstop is located: France, Japan, most of Eastern Europe, etc.

So: why the short interdigital pauses on the 2-1/2" dials?  Probably because the designers didn't anticipate the problem with subscribers dialing too fast.  Once they figured this out, they enlarged the dials and allowed the extra space to prevent wrong numbers when people dialed quickly.   

By the time we get to Germany in the 1930s, that factor would have become known.  So why did Germany stick with a short interdigital pause?  I'm going to guess it had something to do with the response times of the "rotary" switches that were the basis of many German switching systems.  These looked like large single-motion uniselectors rather than the two-motion (up and around) stepping switches as we know them in the US and UK.  I suspect that the design of the switching system was such that control was passed from one such switch to the next in a manner analogous to that of Strowger; *however*, since the equivalent of a "selector" didn't need to make a second motion (sweeping around the contact bank to find a path forward), less interdigital time was needed, and this was reflected in the design of the dials.

Still this leaves us with an anomaly for the W-48 and later German sets: if their switching systems had more rapid action between digits, why did the post-WW2 dial designs allow an interdigital pause equivalent to four dial pulses (400 mSec)?  Or were they looking at export markets where they might sell phones but not switching systems, and wanted to play it safe with the risk of wrong numbers on those systems?

(Quasi-related: occasionally the issue comes up about the "karma" associated with German telephone equipment from the Nazi era.  However as per discussions elsewhere of actual military hardware, one can take an interest in the technology of that era without implying any sympathy for Naziism.  The difference, as with pornography, is the context: a nude isn't porn if it's in an art museum or otherwise not associated with prurient activity.)

Offline dsk

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Re: Location of dial fingerstop
« Reply #10 on: November 20, 2011, 07:11:59 AM »
Nice to know.

Actually one of my favorites from the thirties is the German military Amtsanschliesser 33

Could be translated freely to: "Trunk line phone" or "Trunk unit"  an is actually a rotary dial phone with jack connection for use as a trunk line unit together with a manual field exchange.


http://www.laud.no/ww2/telefon/index.htm


I have one of these tiny little phones includes everything needed, even a buzzer.

I have to take a few pictures together with a WE 500 to compare size.

dsk

Offline GG

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Re: Location of dial fingerstop
« Reply #11 on: November 21, 2011, 04:16:12 AM »


Interesting stuff you have there.  The raised sides and front of the housing of that small German telephone seems designed to protect the edges of the dial while in transit.  The example in mottled brown appears to have been molded from some kind of resin with a lot of wood chips in it, perhaps an adaptation to resource scarcities toward the end of the war?  And very clever of Norway to have double-numbered the dial for both Norwegian and other countries' numbering, after they took over those sets and kept using them. 

I've seen pictures of those before; for some reason I got the impression that they could have a headset plugged into the back of them. 

The switchboard modules for single lines are another clever idea, enabling a small switchboard to be extended indefinitely.  And those backpack cable reels:  I could see those being useful for cable installing crews today.

All of that, including the large site on German radio equipment, adds up to a highly valuable resource for historians. 

There's a link in there to a photography collection: I'm surprised to see that the German military during WW2 had such extensive photography, including the pictures of soldiers using the Enigma machines.  Most of us (Americans) have seen examples of our own WW2 military photography, and we wouldn't expect to see photos of our soldiers using the M-209 cipher machines.  But also, we wouldn't expect to see so much German photography at all, because the impression we have is that the degree of secrecy on the German side was so high that there would be no photography other than things such as photos of various units before they were sent into combat.

Yet in retrospect it makes sense: every wartime government has an interest in keeping up morale at home, and photos from the war are an effective way of doing that.

For that matter, during the Iraq and Afghanistan wars, I was reading a lot of stuff from soldiers at the front, who at that time were allowed and even encouraged (within the limits of operational security) to put up blog sites and include plenty of pictures of themselves and their fellow service members. 

Also I found the link to the Wings For Norway photos of the Norwegian air force during WW2: there's another chunk of WW2 history that most of us (Americans) probably don't know but would be interesting to learn more about.

Offline dsk

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Re: Location of dial fingerstop
« Reply #12 on: November 21, 2011, 05:59:38 AM »
The fingerstop on this is not far away from the 1 digit, i'll guess 150 millisec.
Here are some photos of mine together with a WE 500 to compare the size.

http://smg.photobucket.com/albums/v480/dsk/Telephone/Amtsanschliesser33/?albumview=slideshow

The telephone is molded in something called Presstoff this name has also been used on a leather replica,
but this is more a kind of brown bakelite probably with lots of wood as filler. The handset itselves is heavy black bakelite. Both with nice surface.   The same brown stuff was used as the box on the German field telephone FF33 among many other products.  The Swedish fieldtelephone from 1936 was made in similar stuff.  (The Swedish fieldtelephone was shorted to FELTAPA (Short for field apparatus) but has a double meaning, since APA = monkey in Swedish  :D)

dsk
« Last Edit: November 21, 2011, 03:16:41 PM by d_s_k »

Offline GG

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Re: Location of dial fingerstop
« Reply #13 on: November 29, 2011, 05:08:28 AM »


Hi DSK- Yes, more compact than WE 500 probably due to not having an extended number-ring. 

Presstoff: sounds like a wartime expedient material that turned out to be successful in its own right. 

Field Telephone Apparatus = FelTAPA = Apa >> Ape/monkey: that's funny.  We have some of those kinds of funny name situations here as well.  For example AT&T and NorTel were competing for Worst Brand Name for a while.  AT&T changed their name to Lucent and used a logo that looked like a zero in red pencil that you'd get on a failed test in elementary school: we called that the Lucent Goose-Egg (in the US, a "goose egg" is a zero, and means "no credit for this test" when one fails a test).  Then NorTel changed their branding to Aastra, which sounds like the name of a hemorrhoid remedy:  "Itchy aas? Use Aastra!"  Then AT&T changed yet again, to Avaya, which sounded like "Bye-bye, ya!" as if they were about to exit the market.  Yes we had lots of fun with this from a competitive point of view. 

Funny, I was just writing to Dave about this:-)