DE1957081A1 - Circuit arrangement equipped with a subscriber switch for evaluating counting pulses of a certain frequency in telephone systems, in particular telephone devices, e.g. Coin telephones or subscriber sets - Google Patents

Description

So holding arrangement equipped with a participant switch for evaluation of counting pulses of a certain frequency in telephone systems, especially in telephone terminal equipment, s.B. Payphones or subscriber apparatus The invention relates to a with a subscriber switch equipped circuit arrangement for evaluating counting pulses certain frequency in telephone systems, especially in telephone terminal equipment, s.B. Pay phones or subscriber sets.

To register or collect the call charge units a Fernspreohendstelle are from the telephone exchange from alternating current counting pulses certain frequency over both speech wires to the terminal.

Alternating voltages with have proven to be particularly suitable for counting pulses Frequensen proven outside the Hdr range, e.g. 16 kHs.

For long-distance calls, the counting pulses are usually generated during the Conversation, transferred after the call for local calls, whereby for local calls only one counting pulse is transmitted, while the counting pulses each on long-distance calls are transmitted at different intervals according to the remote dialing tariff. the end For reasons of transmission technology and economy, counting pulses are proportionate small amplitud. used, which duroh the attenuation of the transmission line still is decreased.

Various approaches are known for evaluating the counting pulses. Tin example, the counting pulse is used directly to control an evaluation device, s.B. a counting relay or a cashier circuit.

The disadvantage here is that only short lines can be used safely Response of the evaluation devices concerned is achieved. To longer lines to be able to bridge, circuit arrangements with transistor amplifiers are known, which are fed from the telephone exchange. To separate the alternating speech voltages and the counting pulse is a subscriber switch connected in front of a transistor provided, which consists of a steepened low-pass half-element and a band-pass half-element with a series capacitor arranged symmetrically in the primary winding of the transformer consists.

The low-pass half-element consists of a capacitor and a transformer with two windings whose selectivity is bridged by one with a capacitor third transformer winding is increased. The bandpass half-member consists of one Balun transformer, two separate coils and two capacitors.

A transistor switching amplifier is connected to the bandpass half-element the external device, see B. a counting relay, connected.

This circuit arrangement has technological disadvantages, in particular in the large number of nine windings for the two transformers and the two Coils are justified.

The number of windows heats up the miniaturization of the holding arrangement and also has a strong influence on efficient production. Furthermore, the production the coils and transformers are relatively time-consuming, which has a negative impact on the flow, production of telephone terminal equipment.

The purpose of the invention is this subscriber line in its structure to simplify and design so that they are suitable for efficient production is.

The invention is based on the object of a circuit arrangement To create the evaluation of counting pulses, the subscriber switch without a bandpass half-member get by and without their function is impaired.

This object is achieved according to the invention in that a third Winding of the transformer of the low-pass half-element is an RC-coupled selective amplifier is switched on, so that the counting pulses are coupled out directly from the low-pass half-element are fed to the evaluation device via the selective amplifier.

For connecting the RC-coupled selective amplifier to the third Winding of the transformer of the low-pass half-element, a voltage divider is provided, one of which is a high resistance resistor in order to flatten the attenuation curve of the low-pass half-element that attenuates the counting pulses in the direction of the subscriber, to avoid. The high-resistance resistor is divided into a fixed resistor and an adjustable one Resistance subdivided, so that it can be adapted to different line lengths and thus a decrease or increase in the bandwidth of the selective amplifier is guaranteed.

Parallel sum input of the selective amplifier and to the other resistor of the voltage divider, an adjustable resistor is switched on, the component of an RC element is so that the selective amplifier on the frequency the counting pulses can be adjusted.

At the output of the selective amplifier a CD element is provided that a conversion of the counting pulses into digital signals of a defined length and amplitude causes.

Based on an embodiment shown in the drawing the invention is explained in more detail.

The between the line connections a / b; a1 / b1 switched on low-pass half-element TP consists of the windings WI; W2 of a transformer U and a capacitor Cl. A parallel resonance circuit is used to steepen the attenuation curve of the low-pass half-element TP, from one winding W1 of the low-pass half-element TP and a capacitor C2 is formed. The parallel resonance circuit Wl / C2 is set to the frequency of the counting pulses, e.g.

16 kHz, tuned. As a result, the counting pulses in the direction of Participants sufficiently attenuated. An additional winding to steepen the This means that there is no damping curve.

A voltage divider is connected to a third winding W3 of the transformer R1; R2 an RC-coupled selective amplifier V is connected. The one resistance R1 of the voltage divider has a high resistance and is divided into two partial resistances one of which is adjustable.

In parallel with the input of the selective amplifier V and the other resistor R2 of the voltage divider RI; R2 is a controllable resistor R3 switched on, the Part of an RC element, consisting of the resistors R2; R3 and the capacitors C3; C4 'is. The RC element R2; R3 / C3; C4 is with the help of the adjustable resistance R3 to the frequency of the counting pulses, e.g.

16 kHz, abstiniritar. An at the output output of the Selekti v intended CD element, consisting of a capacitor C5 and a diode D, takes care of the implementation the counting pulses in digital signals, their DC voltage by means of an RC combination 34; C6 is fed smoothly to an evaluation circuit A, e.g. a counting relay.

The low-pass half-element TP is designed so that speech frequencies up to 3400 Hz experience no attenuation.

The counting pulses of a certain frequency arriving from the office, e.g.

16 kHs are made via the third winding W3 of the transformer II the low-pass half-element TP decoupled, tapped at the resistor R2 and arrive reinforced on the evaluation device A.

Evaluation device A and selective amplifier V can be plugged in Execute building units.

List of the reference symbols a; b; a; b1 = line connections TP = Low-pass half-element Ü = transformer W1 to W3 = windings C1 to C6 = capacitors R1 to R4 = resistors D = diode V = selective amplifier A = evaluation device

Claims (4)

Claims 1. Circuit arrangement equipped with a subscriber switch for evaluating counting pulses of a certain frequency in telephone systems, in particular Telephone terminals, e.g. Coin-operated telephones or subscriber sets where in the subscriber switch a steepened low-pass half-member is provided, which from consists of two windings of a transformer and a capacitor and one of which Winding together with another capacitor forms a parallel resonance circuit, characterized in that a third winding (W3) of the transformer (Ü) des Low-pass half-element (TP) an RC-coupled selective amplifier (V) is connected. 2. Circuit arrangement according to claim 1, characterized in that a voltage divider (R1; R2) is provided, of which a resistor (R1) is designed with a high resistance and in a Fixed resistor and an adjustable resistor is divided. 3. Circuit arrangement according to claim 1 and 2, characterized in that that parallel to the input of the selective amplifier (V) and parallel to the other resistor (R2) dt voltage divider CR1; R2) an adjustable resistor (R3) is switched on, the component of an RC element CR2; R3 / C3; C4) is based on the frequency of the counting pulses is matched. 4. Circuit arrangement according to claim 1, characterized in that At the output of the selective amplifier (V) a CD element (C5 D) is provided, which is used for The purpose of this is to convert the counting pulses into digital signals. Blank page