• Why ?

• Because you can always see how much call credit you have left.

• Because you can even insert 5 Franc coins even after the coins you have already inserted. This allows you to call your friends abroad.

• Because a buzzing tone and flashing lights alert you when you have only 10 seconds of call time left. This allows you to insert more coins at your leisure

• Because you really make use of your money - if you haven't used up all our money yet you can use it on further calls with the simple push of a button.

• The AZ044 presents itself in a shiny chrome-steel casing.

Cashier stations have existed in Switzerland since 1932. They have become indispensable, offering a broad public direct access to the telephone network.

Because call charges and surcharges must be collected immediately, these stations are considerably more complex than a conventional telephone.

The design and functionality of the various cashier station models have therefore always depended heavily on the current state of switching technology, with particular emphasis on the fact that the effort is increasingly shifting from the exchange equipment to the station.

With the Type M (Fig. 1), for example, the inserted amount of money is still checked in the telephone exchange by the exchange equipment. The new model, AZ 44 (Fig. 2),

on the other hand, no longer requires exchange equipment and can be freely connected to any standard connection line.

Electronic controls have also largely replaced the previous, electromechanical functions.

Cashier Station AZ 44

AZ 44 Prepayment Telephone

Peter Guyer, Bern

Summary. The new cashier station was put into operation in 1977. In addition to the most important requirements, the mechanical structure and functionality of the electronically controlled device, which can be used on any standard connection line, are described. The article concludes with a look at the customer-friendly operation and installation of this modernly designed device.

Abstract. The author presents the new prepayment telephone, in service since 1977. In addition to the most important requirements this device must meet, he describes its mechanical construction and electronically controlled operation, noting that it can be connected to any standard connection line. He concludes his article by giving a brief overview of its ease of use by the user as well as the installation of the device, designed according to modern principles.

621.395.663.6

Prepayment device AZ 44

Abstract. The new prepayment device AZ 44 was put into operation in 1977. In addition to the most important requirements, the author describes the mechanical structure and operation of the above-mentioned prepayment device, which is electronically controlled and can be connected to any normal connection line. Furthermore, the author points out how simple and convenient the device is for the subscriber to use and ends his article with a description of the modern system.

1 Introduction

Cashier stations have existed in Switzerland since 1932. They have become indispensable, offering a broad public direct access to the telephone network. Because call charges and surcharges must be collected immediately, these stations are considerably more complicated than a conventional telephone. The structure and functionality of the various cashier station models have therefore always depended heavily on the current state of switching technology, with it being particularly noticeable that the effort is increasingly shifting from the exchange equipment to the station With Type M (Fig. 1), for example, the inserted amount of money is checked in the telephone exchange by the exchange equipment. The new model, AZ 44 (Fig. 2), on the other hand, no longer requires exchange equipment and can be freely connected to any standard connection line. Electronic controls are also largely replacing the previous, electromechanical functions. The impetus for replacing the currently common AZ1 cashier station (Fig. 3) was the standardization of the surcharge to 20 cents per connection. Previously, 10 cents per connection had to be paid for local and short-distance calls, and 20 cents per connection for long-distance calls. Recently, burglary resistance, and since the introduction of international direct dialing, fraud protection, have also left much to be desired.

1 Introduction

In Switzerland, there can no longer be any question of abandoning prepayment telephones, which have provided a large number of people with direct access to the telephone network since 1932. Since call charges and surcharges must be collected immediately, however, these telephones are significantly more complicated than an ordinary telephone. Therefore, the construction and operation of the various models of prepayment telephones have always depended, to a large extent, on

26894

Anyone who intentionally impairs the proper functioning of the coin machine will be prosecuted.

Anyone who intentionally interferes with the operation of the device will be brought to justice

PTT

Anyone who intentionally hinders the proper functioning of the appliance will be prosecuted.

PTT

Fig. 1

2 Task

The specifications require a station with the following key features:

Local, national, continental, and intercontinental traffic. Intercontinental traffic (code numbers 001, 002, 005...009) must be blocked, but it must be possible to unblock it easily.

For business traffic (all numbers beginning with 1), an identification tone must be sent to the central office, which is switched off by the first tax pulse. Normal calls to the cashier station are possible; controlled coin insertion is omitted.

The tax pulse unit is 10 cents. A surcharge of 20 cents is added for each taxable call.

120

Cashier station type M, in the version still found today, in service since 1948 - Cashier station type M, in the version still found today, in service since 1948

Technical Bulletins PTT 3/1977

Microphone hung up.

Fault

FAULT

START

Fault

Microphone hung up

Microphone off-hook

Call ended

Microphone hung up

Call

Microphone off-hook

Call

Coin registered

Coin processed

CALL

COIN VERIFICATION

QUERY

Tax pulse registered

Tax pulse processed

TAXIMPULS

PROCESSING

Redial remaining credit

Warning time expired

DISCONNECT ACCOUNT

Dialing pulse registered

Dialing pulse processed

WAHLIMPULS

Error

Fault

Credit

used up

Error

ELECTION Fault

Fig. 7

Program Distribution - Program Distribution

Microphone on hook - Microphone on hook

Start - Departure

Dérangement disorder

Call Apple

Call ended

Microphone off hook - Microphone off hook

Abfrage Response

Reelection - additional selection

Residual Assets

Cut, cut off, cut off, cut off

Warning time expired - Warning time expired

323 Power supply and credit display

The power supply unit supplies the various modules with the necessary voltages, namely

Microprocessor 15 V

C-MOS-Logic

Display 5 V

Magnet

12 V

24 V

The input voltage is 24 V AC or 24 V DC. All outputs, except for the 24 V output, are short-circuit-proof. Supply voltage failures of up to 1 s are bridged

The power consumption, measured on the primary side (220 V) of the supplying transformer, is

16 VA in idle position

25 VA in operation

(average values)

The four-digit balance display consists of 7-segment gallium phosphide display elements. They ensure good legibility; moreover, these elements have a long service life.

4 Operation

Compared to earlier types, the new AZ 44 cashier station is considerably more user-friendly, mainly thanks to its optimal change return and the redial button. After picking up the microphone, the balance indicator begins to flash to prompt the user to insert money. As soon as the minimum amount (40 centimes) is reached, the balance is continuously displayed.

124

Coin announced - Announced currency

Coin verification - Currency verification

Coin processed - Treated coin

Error Default

Tax impulse announced - Tax impulse announced

Taximpuls processed - Tax impulse processed

Credit used up - Avoir consommé

Selection pulse announced - Selection pulse processed

Selection impulse discrimination

322 Telephone circuit and interface

The basic diagram of this circuit is given in Figure 8. The charge pulse receiver can be exchanged for 12 kHz or 50 Hz. The telephone circuit (2) corresponds to that of the telephone set of the model 70. The call receiver operates at call frequencies of 16% to 50 Hz. A selection pulse counting device (4) is used to block the selection of certain call numbers. A warning signal produced by the generator (5) makes it possible to identify the prepayment station in incoming and outgoing traffic to the service numbers. The warning tone prompts for additional payment when the credit is exhausted. The circuits (6, 7, 9) monitor the change verification units and the flasher (8) controls the optical invitation for additional payment. The WFG relay is responsible for authorizing selection when the minimum amount has been entered. When the asset is fully used or if the voltage fails, the BLR relay automatically interrupts communication.

323 Power supply and display of credit

The power supply device provides the necessary voltages to the different units, namely

to the microprocessor

to 12V C-MOS logic

on display

with magnets

15 V

5 V

24 V

The input voltage is 24 V~ or 24 V =. All outputs outside 24 V are set in a re-

Technical Bulletins PTT 3/1977

Fig. 6

Functional Principle of the Coin Checker and Magazine Unit

1 Coin Checker with Coin Slot and Insertion Blocking Flap

2 Coin Checker - Insertion Control

3 Clamping Station for Deformed Coins - Blocking Device for

4 Minimum mass and alloy testing point

Checking Minimum Dimensions and Alloy

5 Coin Channel Monitoring - Monitoring the Magazine Channel

6 Money store

7 Cash Register

8 Money Return - Return of Money

integrated circuits (IC), great flexibility, higher reliability, simple service (test programs), and low costs for any subsequent modifications. The microprocessor's task is to process all information applied to its inputs according to the programs written specifically for this application and stored in program memories (ROM). Figure 7 shows the division of the individual programs.

322 Speech circuit and interface

Figure 8 shows the block diagram of this circuit. The plug-in tax pulse receiver can be exchanged for 12 kHz or 50 Hz. The speech circuit (2) corresponds to that of the Model 70 telephone. The call receiver responds to ringing voltage frequencies of 163...50 Hz. The dial pulse scanning circuit (4) is used to block call numbers. The warning signal generated by the generator (5) allows the cashier station to recognize incoming calls and outgoing calls to service numbers. When the credit is exhausted, the warning tone acoustically requests additional payment. The circuits (6, 7, 9) monitor the coin validator units, and the indicator (8) activates the optical additional payment request. The WFG relay enables dialing after the minimum amount has been inserted. If the credit is exhausted or the power supply fails, the BLR relay forcibly disconnects the connection

3 Execution

31 Mechanical Part

Figure 2 shows the AZ 44 coin-operated station. The use of a chrome-plated steel housing, equipped with sturdy hinges and locks, has significantly improved burglary resistance. The coin-operated station mounted on the concrete base is able to meet even higher burglary resistance requirements (Fig. 4). In this case, the cash register, which is no longer located in the device but in the base, is connected to the device itself by a channel lined with baffles that prevent access to the cash register when the device is dismantled.

The central part of the device, forming a console, with a call dial and credit balance display, offers good visibility for both short and tall people

Figure 5 illustrates the open device. The cover houses the balance display and a coin checker and magazine unit for each coin denomination. Two printed circuit boards, including the telephone circuit, the interface, and the control device, are mounted on a movable frame. The power supply, forming a compact unit, is housed in the lower part of the housing. All these units are pluggable, which facilitates maintenance work or possible modifications.

Figure 6 shows the operating principle of the coin checker and magazine unit. The maximum dimensions of the coins are checked as they pass through the insertion slot (1). The insertion control (2) announces the presence of a coin and instructs the control to close the open blocking flap The blocking device (3) holds back the deformed coins until the measuring cycle of approximately 1.5 s is complete. These coins then pass directly into the restitution channel, which prevents blockages in the magazine channel. The minimum dimensions and alloy of the coins used are checked at the measuring point (4). Counterfeit coins pass into the restitution channel (8). Genuine coins fall into the magazine (6), from where they are transported by the collection lever into the cash register (7) or by the restitution lever into the restitution channel (8). When the magazines are completely full, the additional money paid in falls into the restitution channel.

32 Electronic Circuits

321 Control

A microprocessor controls the device. Compared to the logic circuits used previously, this solution offers various advantages, such as, for example, a small number of integrated circuits, great flexibility, increased reliability, simple service (test programs), and reduced costs for possible subsequent modifications. The microprocessor's task is to process all the information appearing at its inputs according to programs specially written for this application and stored in the program memories (ROM). Figure 7 shows the distribution of the various programs.

123

2

1

6

8

PTT Technical Bulletin 3/1977

I

wfg

blr

at

Central

Oh

5

2

3

Fig. 8

Block diagram of the telephone circuit and interface. Diagram

1. Taxi pulse receiver - Receiver of the call pulses

2. Telephone circuit - Telephone circuit

4. Selection pulse counting - Counting of the selection pulses

3. Call receiver - Call receiver

5. Acoustic and visual warning signal generator

6 Monitoring of the credit flaps

7 Slot flap monitoring

duction

9 Clock generator for photo scanning

8. Flasher

Photoelectric signal

BLR. Busy relay - Busy relay

WFGW. Selection release relay

Impulskontakt - Impulse contact

Central

and the phone number dialing is enabled. The order in which the coins are inserted is arbitrary. The credit is reduced by surcharges and tax pulses. If the credit is exhausted during the call, a short warning tone is heard in the handset, and the credit display begins to flash as a request to pay more. If no money is inserted, the connection is disconnected after about 10 seconds. However, if there is still credit left after the call (at least 40 cents), this can be used for one or more subsequent calls by pressing the redial key If an incorrect digit was dialed when dialing the number, you can also start dialing again by pressing this button without having to return the money and insert it again. The redial button interrupts the connection without initiating the payment process, as is the case when the microphone is hung up. If there is still credit available when the microphone is hung up, it is optimally returned. This means that the unused amount is refunded, provided the previously inserted coins allow it. For cost and security reasons, the machine is not equipped with a coin changer.

To ensure that the user has a quick overview of the operating procedure, an operating manual is posted in each booth. The essential operations are represented symbolically alongside the text in four languages.

Short-circuit-proof. Failures of the supply voltage of up to 1 second are bridged. The power consumption, measured at the primary of the supply transformer (220 V), is

approximately 16 VA in the idle position

approximately 25 VA in operation

(average values)

The 4-digit credit display consists of 7-segment gallium phosphide elements, which guarantee good readability and a long service life.

4 Operation

Compared to its predecessors, the new prepayment station is more user-friendly, mainly due to the optimal money return and the additional selection key. With the microtelephone raised, the credit indicator begins flashing to prompt the user to insert money. As soon as the minimum amount (currently 40 cents) is reached, the credit is displayed permanently and the call number can be dialed. The order in which the coins are inserted is completely free and left to the customer's discretion When the credit, which is reduced by the surcharge and the charge pulses, is used up during the conversation, a brief warning signal is heard in the earpiece and the display starts flashing as an invitation to make the additional payment. If the user does not insert any more coins, the call is interrupted after about 10 seconds. If, on the other hand, the credit (at least 40 cents) is not used up at the end of the conversation, it can be used for one or more subsequent conversations. To do this, simply press the additional selection key. If a user makes a selection error, he can also start the operation again after pressing this key, without the money having been returned and having to be reintroduced. The additional selection key interrupts the call, without, however, triggering the collection process, as is done when the microtelephone is hung up. In the latter case, any remaining balance is returned in the fairest possible manner; this means that the amount not used is refunded, provided that the coins previously inserted allow it. For reasons of cost and security, the machine is not equipped with a money changer.

The essential operations are, in addition to the explanations given in four languages, also presented in the form of symbols on the operating instructions posted in each booth, so that the user can quickly understand the sequence of operations

5 Installation

The AZ 44 coin-operated station can be mounted in the wall frames previously used for AZ 1 devices. Likewise, the connections remain unchanged; the ~ terminals are used to power the device. Depending on requirements, the coin-operated station can be powered at 24 V~ or 24 V =, which

125

9

BLR

WFG

5 Installation

The AZ 44 payment station can be mounted in the wall frames previously used for the AZ-1 machines

PTT Technical Bulletin 3/1977

Likewise, the connections remain unchanged, with the AC terminals (~) serving to power the device. The station can be powered with 24 V~ or 24 V =, as required. This is usually done by a twilight switch or a 200/24 ​​V~ transformer.

If the concrete base is used, special installation guidelines apply.

6 Conclusions

The AZ 44 cashier station offers both the user and the PTT companies new, advantageous features. Its design, the use of new technologies and materials, and the wide range of adaptability in the event of changes make it a future-proof device.

which is generally done from the twilight switch or a 220/24 V~ transformer.

When the concrete base is used, special installation instructions apply.

6 Conclusions

The AZ 44 prepayment station offers new advantages to both the user and the PTT company. Its shape and construction, the application of new materials and technologies, and its high adaptability during modifications make it a device of the future.

The next issue features, among other things,

You will be able to read in the next issue

K. Waber

Digital concentrator for a PCM switching system Digital concentrator for a PCM switching system

B. Rütter

Computer-controlled measuring station for quality measurements on VHF radio transmitters

Ch. Baumann

New procedure for requesting and commissioning telephone connections

New registration and activation procedure for telephone connections

P. Guyer

126

Prepayment station AZ 44

Technical Bulletins PTT 3/1977

10 20 1.-

90-

Fig. 2

Cashier station AZ 44, in operation since 1977 AZ 44 coin-operated station, in operation since 1977

1 Coin input for 4 coins (10, 20 centimes, 1, 5 francs) - Money input for 4 coins (10, 20 centimes, 1, 5 francs)

2 number switches - dial pad

3 Window with call number and location display with call number and target location designation

4 Cash display - Display of credit note

5 Cash return - Return of money

6 Selection key - Additional selection key

7 Apparateteil - Device part

8 Cash register part

levied. A change option in 10-centimeter increments up to 90 centimeter is to be provided. The selection is only released when the inserted money corresponds to at least two tax pulse units, including the surcharge

(currently 40 centimeter).

The polarity-independent cashier station is operated via a normal exchange line with the criteria of a normal subscriber connection.

The cashier station is powered by 24 V AC or 24 V DC. In the event of a power failure, free telephone calls must not be possible. Money left in storage units must be cashed in once the operating voltage returns.

3 Design

31 Mechanical Part

Figure 2 shows the AZ 44 cashier station. Thanks to a chrome-steel housing with robust hinges and locks, burglar resistance has been significantly improved. The cashier station mounted on the concrete base can meet even higher burglar resistance requirements

PTT Technical Bulletin 3/1977

of the level reached by switching technology, it being understood that it is particularly striking to note that the technological means implemented are transferred to an increasing extent from the equipment at the exchange to the device. If, for example, the amount introduced into the type M prepayment set (Fig. 1) is still controlled by the equipment installed at the telephone exchange, the new AZ 44 model (Fig. 2) no longer requires any exchange equipment and can be connected without any restrictions to any ordinary connecting line. Similarly, electronic controls are increasingly replacing the old electromagnetic functions. The fact of standardizing the surcharge at 20 centimes per call, which previously stood at 10 centimes for local and suburban traffic and 20 centimes for long-distance traffic, has prompted the replacement of the AZ 1 prepayment set (Fig. 3) currently in service While it is true that the tamper-resistance of the devices has left something to be desired in recent times, it must be recognized that, since the introduction of international automatic selection, security against fraud has not been satisfactory either.

2 Imposed tasks

The specifications require a device meeting the following main characteristics:

Possibility of local, national, continental, and intercontinental traffic. If intercontinental traffic is to be blocked

10 50

20

50.00

Fig. 3

Kassierstation AZ 1, since 1966 in Operation AZ 1, in operation since 1966 Prepayment station

121

*

8