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Automatic Electric Type 34A3A Monophone ('easy lift variant')

Started by unbeldi, August 18, 2015, 10:50:05 AM

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unbeldi

Automatic Electric produced a version of the Type 34A3 desk telephone that they advertised as the easy lift variant, type 34A3A. This is supported by only a few sources, but is amply supported by the record of found examples.  The type was advertised in telephony periodicals ca. 1938, e.g. , as reported here and pictured below, and also was mentioned in a remark in a 1939 article in Automatic Electric Review, which introduced the new Type 40. It mentioned that the older models were still going to be available.

Found specimens of this variant have a modified cradle area with a space in the rear that permits insertion of two fingers to lift the telephone set.  These sets had the ordering numbers L–250–A0 and L–253–A0 stamped on the bottom plate of the dial versions. Manual versions with dial blank were labeled –B0.

AE had to literally create the space for this finger hold; therefor they had to lay the ringer flat on the base plate.  Previously it was mounted at an angle towards the rear of the phone completely filling the space underneath the hookswitch.  The condensers, one or two, were place on the sides of the ringer, topped by a four-terminal screw connector plate.

The L-250 was for metallic (bridged) ringing service using a two-conductor mounting cord, while the L-253 variant was for grounded ringing with a three-conductor cord and a separate ringing condenser.

Presented here are circuit and wiring diagrams for these telephones as equipped with a dial.
The circuit diagram in the first exhibit here is drawn according to AE Form number D-53677 Issue 1. The insert in the upper right corner are the changes from Form D-53676 Issue 1 for the modifications for grounded ringing. Both forms are shown in the second and third exhibit, respectively.

The circuit of this phone is identical to the circuit of the standard Type 34A3, but it has additional connection points on the two terminal strips next to the ringer. The standard version only has screw terminals on top of the end blocks of the induction coil. The circuit presented here includes the extra connection points as numbered circles on the traces.

The circuit diagram is drawn in the on-hook state, so that only the ringer is connected to the telephone line which is connected to the L1 and L2 terminal points (in pink).  This is in contrast to the original wiring labels, which presented the switches in the off-hook position, in operating mode.

Circuit diagrams can be drawn in many layouts; this circuit diagram emphasizes the signaling and transmission circuit in a straight line down the center from line connection L1 to L2. To the left is the ringing bridge, and to the right is the handset and reception circuitry.

The hookswitches are labeled by HS followed by a serial number. The hookswitch has essentially two separate switches, a three-terminal switch, and a simple two-terminal switch, both close when operated (off-hook).  HS1a and HS1b are the components of three-terminal switch, which results in connection of all three contacts, and places the transmitter (TX) into the local loop when the dial is not operated.  When dialing, off-normal switch ON1 closes and shunts the transmitter so that the dial pulses from switch DP are sent out to the loop. DP opens the appropriate number of times for each digit dialed.  The pulses traverse the primary winding (P) of the induction coil, which has a DC resistance of 20 Ω.  When dialing, the receiver is also shunted by dial switch ON2, so that the user cannot hear the pulses.

The hookswitch (HS2) also connects the receiver to the secondary winding (S, 30 Ω) of the induction coil. The primary and secondary windings function like a traditional booster circuit.

The anti-sidetone feature of the circuit is implemented by a tertiary winding (T) added to the induction coil. It is wound from wire with inherently higher resistivity, resulting in a total DC resistance of 220 Ω. This resistance functions as the balancing network and is drawn explicitly in my diagram as a resistor (--\/\/\--, above the T winding).

In the version of this telephone type for metallic, line-bridged ringing, the condenser of the circuit is shared between the ringing circuit and the audio circuit. It has a capacitance of 1 µF.  The grounded ringing variant, L-253-A0, uses a separate 1 µF condenser for the ringing circuit. This isolates the audio circuit from ground.

This type of telephone could be equipped with either a straight-line ringer (as indicated in the diagrams), or with a frequency-selective ringer, in which case capacitor C1 would be chosen appropriately for each frequency of ringing current.


Discussions of observations of these AE34 types may be found on this forum:
* http://www.classicrotaryphones.com/forum/index.php?topic=14802
* http://www.classicrotaryphones.com/forum/index.php?topic=13919
* http://www.classicrotaryphones.com/forum/index.php?topic=14369
* http://www.classicrotaryphones.com/forum/index.php?topic=3667

magicbrain

My first phone of the year is a AE 34A3A "Easy Lift" version - it was pricey, but I was glad to get it as they don't show up often.




Bruce

HarrySmith

What is Easy Lift??

I am not seeing all the pictures for some reason?
Harry Smith
ATCA 4434
TCI

"There is no try,
there is only
do or do not"

Doug Rose

Quote from: magicbrain on February 01, 2019, 01:11:02 PM
My first phone of the year is a AE 34A3A "Easy Lift" version - it was pricey, but I was glad to get it as they don't show up often.





really tough phone to get, still looking for mine. It is a beauty....congrats....Doug
Kidphone

HarrySmith

A phone you don't have Doug?? I did not think that was possible!
Harry Smith
ATCA 4434
TCI

"There is no try,
there is only
do or do not"

TelePlay

Quote from: HarrySmith on February 01, 2019, 01:24:50 PM
What is Easy Lift??

I am not seeing all the pictures for some reason?

Looks like a built in, black hand hold. I've never seen one of these, I don't think so. Usually it's a chrome plate from plunger to plunger.

A picture of this with the handset removed would be interesting.

magicbrain

Quote from: TelePlay on February 01, 2019, 02:32:19 PM
Looks like a built in, black hand hold. I've never seen one of these, I don't think so. Usually it's a chrome plate from plunger to plunger.

A picture of this with the handset removed would be interesting.

Those are the auction pictures I put up - I haven't had time lately for our favorite obsession hobby - I'll try to add some of my own pics showing more details.
Bruce

HarrySmith

I did a Google search for Automatic Electric Easy Lift Telephone. It brought me right back here! There was a post about it, a very lengthy post as was the habit of this former member. No pictures but a very detailed explanation about it and an old ad:

http://www.classicrotaryphones.com/forum/index.php?topic=14814.0
Harry Smith
ATCA 4434
TCI

"There is no try,
there is only
do or do not"

Doug Rose

Quote from: HarrySmith on February 01, 2019, 02:24:33 PM
A phone you don't have Doug?? I did not think that was possible!
Harry....it do happen! I have my want list and this is high on it. Funny thing is as soon as you find a phone you really wanted...it is easily replaced by next phone up. I don't think that will ever change. There is always the next must have.  It's what make this hobby fun...Doug
Kidphone

magicbrain

A few more pictures.




Bruce

magicbrain

Any idea what these numbers in red grease pencil might mean?
Bruce

Jim Stettler

Quote from: magicbrain on February 01, 2019, 01:11:02 PM
My first phone of the year is a AE 34A3A "Easy Lift" version - it was pricey, but I was glad to get it as they don't show up often.





Sounds like a find of the month to me.
Jim
You live, You learn,
You die, you forget it all.

wds

Here's a link to a couple other threads of the same phone.  Definitely a rare phone.

easy lift
Dave

Doug Rose

The more I look at is, this cut looks like it is an aftermarket upgrade. It does not look even. What do you think? An exposed plunger.?....Doug
Kidphone

wds

I don't think it's aftermarket.  I believe that AE introduced this model to compete with other phones that had handles, and maybe also to get rid of some left over model 34 shells.
Dave