Prepay how did it actually work?

[dsk]

If I understand this, you have to insert money to call, but the coin was not collected before you went on hook?
Could that be right? Couldn't you just press the coin return knob before hung up?
Or was it just collecting on polarity reversal, and the transmitter remained unblocked. Collecting more money was manually controlled by the operator listening to the bell sound of collecting?

Really confusing for me, The Norwegian payphones was simpler post pay like variants.

dsk

[Phonesrfun]

The coin passed through the hopper to a switch that gave dial tone which allowed for the placement of the call.  Once the coin got to that point, the coin return button would not return the coin.  The only way the coin was returned at that point was if the central office sent a voltage to the coin relay to tip the coin into the return chute.

The coin return button was pretty much only a bent coin return button, and only functioned in the upper portion of the coin track.  So, if you got dial tone, the only way to get your money back was to hang up before the call was answered or by dialing the operator or 911, or have a busy or non-existent number.

[ESalter]

A good explanation of the coin return lever is exactly how it's marked on the phone.  It isn't a "Coin Return", it's a "Coin Release" and it does just that, it opens up the validator  to release whatever may have gotten stuck in the validator(knockout slugs, pennies, foreign coins, etc) and not made it down to the coin relay.

---Eric

[dsk]

Thank you!
dsk

[poplar1]

Western Electric prepay: originally (before DTF Dial Tone First):

Going off-hook, you did not have dial tone. These were Ground Start Coin Lines similar to GS PBX trunks. Once the coin(s) traveled through the coin chute, it activated a switch in the hopper which completed a path from one side of the line through the coin relay to ground, which signaled the central office to return dial tone.

If you called the operator, the coin was returned right away--as soon as she answered if I recall correctly. Otherwise, the coin stayed in the hopper until several seconds after you hung up. If you didn't finish dialing the complete number, or if the line called was busy or didn't answer, then there was no polarity reversal, and the coin deposit was returned. Otherwise, the money went into the coin vault, except on "free" calls where there was no reverse battery supervision (calls to 411, intercepted numbers, etc.)

As far as I know, the transmitters weren't blocked in WE prepay multi-slot phones. Some had "Dial-Shorting Relays" to prevent dialing out even if you were able to draw dial tone (by, for example, grounding a conductor inside the handset cord or the transmitter). Still, if you were clever enough to get a free dial tone, you probably knew how to dial with the switch hook.

Years later, many were converted to "dial tone first" which allowed calls to Operator, 911 (Emergency), etc., to be completed even if you didn't deposit any coins. The central office equipment had to be modified not only to send dial tone right away but also to screen the numbers dialed. If you dialed a regular 7-digit number without first depositing 10 cents, then the call was diverted to a recorded announcement telling you to hang up, deposit 10c, then dial the number.

In other words, it became more and more complex to allow "free" calls to emergency numbers, even though semi-postpay (AE)/postpay (WE/NE) phones had allowed this all along.

[dsk]

Thank you again, this seems interesting, I remember I had polarity reversal at my first extention, something I measured, but did not understand at that time.

The PAP2T adapter has the possibility of reverse polarity, but its only 24V. It could probably be used.
I, m still confused of how the different relays and coils are operated to switch between coin collect or coin return.
polarity sensitive relay? dual coil relay? ...

I have looked at different payphone controller projects, non of those are polarity controlled etc.

When polarity reversal disappeared we (Norway) started with 16 kilohertz pulses when the coin should be collected, this also opened for collecting coins e.g. every 3 minutes for local calls, and shorter interval's  for long distance. (Same system as Germany)  We never got any recorded voice messages.


dsk


PS
I actually did want  an old payphone, just for the know-how, until I realized the high costs, not far from $100 for a complete, but ugly 3-slot'er, and about $ 150 for shipping. If the customs officer are in a bad mode he adds about 30% in vat and fees on the total.  It may end up with $350. This will be an expensive learning, so I try to learn from you for free 
DS

[poplar1]

Here is an explanation of the different types by GG---has anyone heard from GG?

http://www.classicrotaryphones.com/forum/index.php?topic=5864.0


See reply #7

[dsk]

Again, thank you.
That explanation is really informative.

A little off topic, enclosed the name on a local road. Could probably be translated to something like "Nickel Trail"
dsk