Author Topic: Field Trial 500? F-51674-R Discussion  (Read 7478 times)

unbeldi

  • Guest
Re: Field Trial 500? F-51674-R Discussion
« Reply #30 on: June 02, 2016, 08:58:31 AM »
The reason that the set does not have a dial is that the Crystal Lake trial was not a full electronic office. It only tested some subsystems, particularly the tone ringer.  The set probably does not have the ANI circuitry yet for station identification.

Bell Laboratories Record, March 1956, p 116.

unbeldi

  • Guest
Re: Field Trial 500? F-51674-R Discussion
« Reply #31 on: June 02, 2016, 09:05:20 AM »
Here are some new auction pictures not previously seen.

Offline poplar1

  • Hero Member
  • *****
  • Posts: 5866
  • 102C-6 = "Old Brass" Hand Telephone Set
Re: Field Trial 500? F-51674-R Discussion
« Reply #32 on: June 02, 2016, 09:30:12 AM »
The reason that the set does not have a dial is that the Crystal Lake trial was not a full electronic office. It only tested some subsystems, particularly the tone ringer.  The set probably does not have the ANI circuitry yet for station identification.

Bell Laboratories Record, March 1956, p 116.

It has only red and green conductors in the mounting cord, and hex nuts rather than screws blocking the G (ground) terminal on the network. So this set was apparently not for party lines.

Were other sets with tone ringer equipped for tip party ID? If so, did they have to add an inductor, rather than use the tone ringer to detect high resistance to ground when off-hook?
"C'est pas une restauration, c'est une rénovation."--François Martin.

unbeldi

  • Guest
Re: Field Trial 500? F-51674-R Discussion
« Reply #33 on: June 02, 2016, 10:05:42 AM »
It has only red and green conductors in the mounting cord, and hex nuts rather than screws blocking the G (ground) terminal on the network. So this set was apparently not for party lines.

Were other sets with tone ringer equipped for tip party ID? If so, did they have to add an inductor, rather than use the tone ringer to detect high resistance to ground when off-hook?

Party line service worked differently in the Electronic Office than in the traditional plant.  Selective ringing did not require the ground connection, and therefore a two-conductor mounting cord was good enough.
The tone ringer used audible frequencies for ringing at a power level comparable to speech. The telephone set amplified this signal for the tone ringer with a transistor.  Different subscribers on the same line were signaled with different sets of frequency. Selective ringing was achieved by strapping each set on the large connection plate to be responsive only to the frequency assigned for the station.  This was achieved by a resonant  L-C circuit with a set of selectable inductances and two or three capacitances.

This is very similar actually to the principles of the touch tone dial, only in the opposite direction of signaling. Party id generation worked similarly, only in the reverse direction, almost like the TT dial.  However, I don't know whether this was developed already in 1956.

PS: The BLR document that I just posted explains that the indeed the trial involved subscribers on up to eight-party lines.  This was fully-selective ringing even for eight parties. I will try to find out how ANI worked in these cases, but given that the instrument does not have a dial, indicates that placing a call, probably involved the operator anyways.


The paper also states that only ca. 100 lines participated in the trial, yet some 300 telephone sets were involved.
I also seem to remember that the trial participants also still had a traditional line, the test line did not replace the existing service, but I don't remember the source of that statement. I am also wondering whether Crystal Lake was not still a manual exchange anyways at the time, as was the case for Morris, IL. where the full system had its debut.

PS 2:  In my dual line statement, I think I am confusing it with the Morris trial.  In Morris, Western Electric actually built two switches in parallel, one was a crossbar, and the second was the ECO.  The crossbar was finished well ahead of the electronic switch.  Previously, Morris was all manual.

So, I do suspect that Crystal Lake was also manual, obviating the need for dials, and simplifying the testing of tone-ringing telephone sets.  At the exchange, only the outward signaling equipment needed to be replaced by the tone generation system.
« Last Edit: June 02, 2016, 01:30:13 PM by unbeldi »

unbeldi

  • Guest
Re: Field Trial 500? F-51674-R Discussion
« Reply #34 on: June 02, 2016, 10:12:36 AM »
Here is the announcement of the Crystal Lake trial in the BLR:

Offline andre_janew

  • Hero Member
  • *****
  • Posts: 1429
Re: Field Trial 500? F-51674-R Discussion
« Reply #35 on: June 02, 2016, 10:52:27 AM »
It seems to be an attempt at an electronic ringer or what my dad would call a "tweety bird" ringer.  I had no idea they started working on such a ringer so early, but I imagine it had to start sometime.  I have no idea when the first mass produced electronic ringer first appeared, but I think it was a lot later than 1956!

unbeldi

  • Guest
Re: Field Trial 500? F-51674-R Discussion
« Reply #36 on: June 02, 2016, 11:05:34 AM »
It seems to be an attempt at an electronic ringer or what my dad would call a "tweety bird" ringer.  I had no idea they started working on such a ringer so early, but I imagine it had to start sometime.  I have no idea when the first mass produced electronic ringer first appeared, but I think it was a lot later than 1956!

This type of tone ringer was never mass-produced.  It was only used in production once at Morris, IL, for about a year and a half.  For the No. 1 Electronic Switching System (1ESS), which debuted in Succasunna NJ in 1965, they went back to a conventional local loop design.

What Western Electric later called a tone ringer, for example the S1 Tone Ringer, is somewhat different in that it rings from the same high-voltage ringing current that any other telephone uses.  Its transducer however is an electronic ringer amplifying an internally generated dual-frequency signal (~750 and ~1500 Hz) to drive the tweeter.  The high-voltage ringing signal from the line was reduced with a transformer in the ringer set to trigger the oscillator.


PS:  BSP 501-260-100
« Last Edit: June 02, 2016, 11:10:18 AM by unbeldi »

unbeldi

  • Guest
Re: Field Trial 500? F-51674-R Discussion
« Reply #37 on: June 02, 2016, 11:17:11 AM »
What is very unfortunate for the finder, but more so for the buyer of this set, is that the actual ringer appears to have been removed from the set.

Perhaps the seller was actually wise to take whatever private offer (s)he received to cancel the auction.
I can't imagine the set being worth $600 without its most-prized component.


Offline Jim S.

  • Hero Member
  • *****
  • Posts: 3322
Re: Field Trial 500? F-51674-R Discussion
« Reply #38 on: June 02, 2016, 03:10:06 PM »
I have a "bell chime" (style)  ringer that is  a tone ringer.  I think that was the only production model of tone ringers. I have never opened or tested it.

Jim S.
You live, You learn,
You die, you forget it all.

Offline AE_Collector

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 7445
  • AE 2 - AECo's 1st Self Contained Desk Phone 1925
Re: Field Trial 500? F-51674-R Discussion
« Reply #39 on: June 02, 2016, 03:45:04 PM »
The paper also states that only ca. 100 lines participated in the trial, yet some 300 telephone sets were involved.

From the BLR article then all subscribers participated. There were 300 customers on 100 lines due to the party lines.

It seems to be an attempt at an electronic ringer or what my dad would call a "tweety bird" ringer.  I had no idea they started working on such a ringer so early, but I imagine it had to start sometime.  I have no idea when the first mass produced electronic ringer first appeared, but I think it was a lot later than 1956!

Refresh our memory...the desire for a new type of ringer was in conjunction with the development of electronic switching. Either technology didn't exist initially in electronic format to Inexpensively or reliably superimpose the 90 VAC ringing onto the 48VDC lines for ringing OR it was seen as a potential cost saving to go with a newer type of ringing.

The conversion to new CO equipment was the opportunity to make this change to the ringing format. Tone ringing was being designed to meet a need in electronic switching or cost control rather than as a novelty.

Terry
« Last Edit: June 02, 2016, 03:52:24 PM by AE_Collector »

unbeldi

  • Guest
Re: Field Trial 500? F-51674-R Discussion
« Reply #40 on: June 02, 2016, 03:52:50 PM »
I have a "bell chime" (style)  ringer that is  a tone ringer.  I think that was the only production model of tone ringers. I have never opened or tested it.

Jim S.

Are you talking about the F1A BellChime ?
It has a two gongs.

unbeldi

  • Guest
Re: Field Trial 500? F-51674-R Discussion
« Reply #41 on: June 02, 2016, 04:29:21 PM »
From the BLR article then all subscribers participated. There were 300 customers on 100 lines due to the party lines.

Refresh our memory...the desire for a new type of ringer was in conjunction with the development of electronic switching. Either technology didn't exist initially in electronic format to Inexpensively or reliably superimpose the 90 VAC ringing onto the 48VDC lines for ringing OR it was seen as a potential cost saving to go with a newer type of ringing.

The conversion to new CO equipment was the opportunity to make this change to the ringing format. Tone ringing was being designed to meet a need in electronic switching or cost control rather than as a novelty.

Terry

Yes it was solely developed for electronic switching.
In the Morris-type electronic switching system that was already in the design stage in the early 1950s, the signal switching network, which supplies ringing and other tones is also constructed from gas-filled diode cross-point elements, and these could not operate at the high-current (10 mA) and high-voltage (90 V) of traditional ringing with high-impedance C-type ringers, and therefore the ringers had to be redesigned for much less power transmitted through the signal network.  As a result the ringing signal was on the order of less than 1 V to max of 2 volts.   Also, the local loop did not operate at 48 V, but only at ca. 20 V.

Offline poplar1

  • Hero Member
  • *****
  • Posts: 5866
  • 102C-6 = "Old Brass" Hand Telephone Set
Re: Field Trial 500? F-51674-R Discussion
« Reply #42 on: June 02, 2016, 04:44:22 PM »
Are you talking about the F1A BellChime ?
It has a two gongs.

I believe he is talking about the S1A that you mentioned earlier. It has the same cover as the F1A Bell Chime.
"C'est pas une restauration, c'est une rénovation."--François Martin.

Offline Jim S.

  • Hero Member
  • *****
  • Posts: 3322
Re: Field Trial 500? F-51674-R Discussion
« Reply #43 on: June 02, 2016, 04:46:25 PM »
I believe he is talking about the S1A that you mentioned earlier. It has the same cover as the F1A Bell Chime.

That's what I am talking about. 
Jim S.
You live, You learn,
You die, you forget it all.

Offline poplar1

  • Hero Member
  • *****
  • Posts: 5866
  • 102C-6 = "Old Brass" Hand Telephone Set
Re: Field Trial 500? F-51674-R Discussion
« Reply #44 on: June 02, 2016, 04:48:36 PM »
What year did Stromberg-Carlson start using tone ringers in their Petite (?) (Princess Style) sets?
And what about the Ericofons, whether Ericsson or North Electric?
2500DMGB and 2500MMGB sets made by WE/AT&T Technologies?
"C'est pas une restauration, c'est une rénovation."--François Martin.