Western Electric Coin chute/ mech.

[sjt1803]

Can someone explain exactly what the devices are that are employed in a we 233 payphone coin track to detect coin tones.  Are these inductive, or are they transducers?
Exactly what are they, and how do they function?
I just don't recall ever seeing such a device employed in other products.
There is also a condenser and a solenoid on that assy, for what purpose.

If there is a document on the coin chute/mech assy that details it's operation and has a parts breakdown please share it.  I haven't been able to find anything on it.

Thanks

[G-Man]

Can someone explain exactly what the devices are that are employed to "listen" to the coins falling through A WE 233 payphone coin track.

If there is a document on the coin chute/mech assy . . .

It is a mechanically-coupled carbon button microphone that senses the sound of the coin signals (not the sound of the coins themselves) on payphones equipped with handsets and prior to that, paystations with separate transmitters and receivers the transmitter itself transmitted these signals via mechanical coupling.

The TCI Library has probably over a hundred coin telephone related documents.

[G-Man]

Try downloading this Bell System Practice for an explanation of how a 200-series coin telephone works-

Coin Collectors General Information Method Of Operation-


EDIT: shortened link

[sjt1803]

Thank You, that is exactly the document I was looking for and could not find!

[sjt1803]

Is it fair to say:
These carbon based transducers (microphones or signal transmitters) attached to the coin chute in 2 locations on the payphone coin chute assy. are strictly to pickup coin signal tones and to be carried over the voice path.
They are apparently sensitive enough in their placement to allow for the determination of the coin denomination and the number of coins deposited.

So without the central office's participation in the operation of one of these payphones, the coin chute circuitry, including the nickel electromagnet really have no need for connection in the phone.
These parts on the coin chute assy provide cosmetic authenticity, and should be retained as to not devalue the phone.

[G-Man]

"These non used parts on the coin chute assy provide cosmetic authenticity but nothing else."

Well in general terms there is another reason to retain them, in most cases the more complete the payphone is, the more value it retains as a collectable and is likely to appreciate in value.

Not to be a stickler but once again the intent of the signals transmitter(s) was not "strictly to pickup sound, any mechanical sound on the coin chute"   but of the tones generated (and number of times) when they struck the gongs and not to hear the actual coins.

That is the reason damped mountings were used in order that any extraneous sounds such as the mechanical vibrations of a passing train, traffic or of a customer drumming his fingers against the instrument would not be heard by the operator or person at the other end, or at least for it to be greatly diminished. 

Since has been roughly thirty-plus years (+/-) central offices had equipment to supervise calls from 3-slot payphones it is no surprise to experienced collectors that they can only be used as standard telephones unless an outboard controller is installed for demonstration purposes.

[sjt1803]

I wasn't suggesting anyone remove those parts.
I was just pointing out for those of us "new" to collecting payphones it just an interesting fact.

I understand that the intent was to hear specific sounds to make payment determinations, but I put those pickups in circuit and connected them to my scope and a external amplifier as well as to a headset.  Any mechanical sound on that chassis could be heard. Obviously the sound produced by the coins striking the bell and gong would be louder than the movement through the mechanism. And yes your right, I see every effort was made to isolate them from the rest of the chassis, but they are sensitive enough to pickup sound other then just the intended ones. Of course this would all depend on the gain employed.
And of course the operator could care less about the extraneous sounds just those that effected payment.
What all this information does for us I don't know, but it is interesting.
Thanks for your insight,  and information

[G-Man]

The reason I expanded on some of your comments is because this list is used by those who are also new to telephone collecting to further their own knowledge. If they receive the impression that it is ok to dispose of these "excess parts" they may regret it years later when they want to sell or trade their payphone.

"These carbon based transducers (microphones or signal transmitters) attached to the coin chute in 2 locations on the payphone coin chute assy. are strictly to pickup sound, any mechanical sound on the coin chute while they are connected to the talking circuit."

This statement is incorrect and may lead other who search these post in the future to misunderstand the true intent was to pick-up the sounds of the gongs and any residual noise was at least damped if not eliminated completely, depending upon the intensity of the extraneous sounds.

And you are correct in that I also doubt there is much value in these revelations since almost anyone who has ever placed a call on one of these payhones and inserted coins would have also heard the extraneous sounds but most likely never paid much attention to them.

It is always beneficial to ask questions and since you are on the road to gaining a better understanding of their operation, if you have further interest there are additional documents available that provide insight on how the central office handled calls placed from coin telephones.

[sjt1803]

I modified the offending statement in the earlier message to correct what was considered inaccurate.
The intent was to give a generalization of what was going on in laymen s terms.

Only because I found it very interesting.

Not being familiar with the design, I simply thought the operator heard the exterior sound as we did as a customer.

You missed the point,  that was the revelation, not the extraneous sounds.

Hopefully others reading this exchange may find it interesting as well, and not fear asking questions or sharing their discoveries, though maybe only new to them.

Again for the laymen -Some of the telephone terminology such as "Coin Signal Tones" "picked up by two signal transmitters" needs a bit of demystifying, simplified it  becomes a  pair of microphones picking up the sounds of  coins striking a bell or gong and adding it to the voice path.

Lets see how that one fly's

[G-Man]

That makes things clearer for all who may end up reading this in the future.

Also, if you have an interest to do so, an outboard controller can be purchased to simulate the manner in which it originally functioned, included the collection or refunding of coins depending whether the call was answered or a busy signal was returned on local calls.

If you would like to pursue using one, then Dave Hunter (PEI) is our resident controller guru who could assist you.

[sjt1803]

You bring up an interesting point on the use of a payphone controller. There may be a reason to assure those coin chute microphones are connected and in working order. In Prepay operation for example, before the dial tone was established , were the coin tones muted by the phone?
If not, then it will add to the feel of realism for them to be in circuit when connected to a controller.

[G-Man]

Actually for prepay operation the signal transmitter(s) were only used during operator assisted calls.
If a long distance call was being placed she would tell you how much to deposit and then listen for which gongs were being struck by the coins.

Local calls were flat-rate, either a nickel or 10-cents and once the correct amount was deposited the caller could place their call without the assistance of the operator.

The outboard coin controllers for hobby use only supervises whether coins are deposited and once they are either local or long distance calls can be made. The controllers are for demonstration purposes only and are typically used with coin telephones installed in one's den or workshop for the showcasing it when family friends and buddies come-over and visit. It's sorta like having a slot-machine in your den, everybody wants to put in a coin to see if it works.

[poplar1]

You bring up an interesting point on the use of a payphone controller. There may be a reason to assure those coin chute microphones are connected and in working order. In Prepay operation for example, before the dial tone was established , were the coin tones muted by the phone?
If not, then it will add to the feel of realism for them to be in circuit when connected to a controller.

WE prepay phones used special lines that were also ground start: there was no dial tone until the trigger activated by a dime or 2 nickels provided a path to ground to signal the c. o. to return dial tone. So the transmitters could not transmit in the absence of battery. Once you deposited 10c, got dial tone, and dialed the operator, the deposit would be returned as soon as she answered. Once you gave her the number you wanted her to dial, she would then ask you to deposit the appropriate local (10c) or long distance amount. She had C and R keys  to collect or refund your deposit.

Even without a controller, it is still interesting to leave the coin signal transmitters and the electromagnet connected. On a POTS or VOIP line, you can then hear any coins deposited and also hear the electromagnet operate as each number is dialed.

[sjt1803]

Thanks

You bring up an interesting point on the use of a payphone controller. There may be a reason to assure those coin chute microphones are connected and in working order. In Prepay operation for example, before the dial tone was established , were the coin tones muted by the phone?
If not, then it will add to the feel of realism for them to be in circuit when connected to a controller.

WE prepay phones used special lines that were also ground start: there was no dial tone until the trigger activated by a dime or 2 nickels provided a path to ground to signal the c. o. to return dial tone. So the transmitters could not transmit in the absence of battery. Once you deposited 10c, got dial tone, and dialed the operator, the deposit would be returned as soon as she answered. Once you gave her the number you wanted her to dial, she would then ask you to deposit the appropriate local (10c) or long distance amount. She had C and R keys  to collect or refund your deposit.

Even without a controller, it is still interesting to leave the coin signal transmitters and the electromagnet connected. On a POTS or VOIP line, you can then hear any coins deposited and also hear the electromagnet operate as each number is dialed.

Thank You, settled , that is actually what I wanted to know , they will be connected!

[sjt1803]

Update--
With a little help from poplar1, I straighten out the wiring on my 236G  replacement  coin chute.
The 236G and coin chute now wired correctly, definitely adds a plus to the payphone operation.
You can clearly hear the coin tones in the receiver.