DE2536200C2 - Circuit arrangement for monitoring a voice wire in telephone sets - Google Patents

Description

io ■ to create a circuit arrangement of the type mentioned, which monitors in a simple manner the interruption of the speech line when the handset is hung up and evaluates a signal generated during this interruption as a stop signal for the dial pulse contact actuation. V

This object is achieved by the features of claim 1. It results from the dibei Advantage that with the output signal of the selection transmitter can be safely brought into the rest position.

A further development of the invention is that between the base and collector of the transistor a Capacitor is switched. This has the further advantage that there are no short interruptions be evaluated with.

The invention will now be explained in more detail with reference to the embodiment shown in the drawing.

With the actuation of the hook switch GU , the selector transmitter WS is connected to the speech wires a / b and at the same time the capacitor C1 is charged as a voltage store. A voltage divider, formed from the high-resistance resistors R 1 and R 2 , is located between the speech wires and from which the base voltage for the pnp transistor Γ is tapped via a further resistor A3. The emitter is connected to the positive potential + leading voice wire b and the collector via a resistor R 4 to the negative potential - leading voice wire a . When connected to the voltage by the hook switch, the transistor becomes conductive. The output signal R tapped at its collector is sent as a monitoring signal to the selector transmitter WS. If Wahlimformationen are input to the selection station WS in a manner not shown, that controls nsi corresponding to the pulse contact, as is indicated by the dashed line.

The interruptions of the loop by the pulse contact nsi do not affect the switching status of the transistor Γ, since the switch via hook switch GU, contact x. The emitter-base path and the resistors R3 and Rl keep the current flowing through this transistor.

If, on the other hand, the loop is interrupted by contact GU or contact χ , the locks

Dje application relates to a circuit arrangement for monitoring a voice wire for interruption of the supply voltage in telephone sets with a selection transmitter with voltage memory. _J5

In the known telephone sets with a selection transmitter, which are also called telephone sets with unecher tactile dialing are designated, the dialing information is entered into a memory by means of touch dialing and then sent out as a pulse dial. To provide a power supply during loop breaks The election transmitter is to be ensured with a voltage memory by means of the dialing pulses sent Mistake.

Such a telephone set is, for example, 45 transistor T, since the above-mentioned circuit is

is broken. The output signal R thus disappears and has the effect that all devices in the dial-up transmitter are reset.

Brief interruptions in the supply voltage can be bridged by the capacitor C1 connected between the base and the collector.

In order to prevent the voltage across the capacitor Cl on the opening of the contact GU

,,. Voltage divider Rl - Rl the transistor T through

tur circuit should cause the dial pulse contact 55 controls to hold, a diode G / is inserted,
this relay, provided that it is caused by mechanical impacts in the It goes without saying that the ones shown here

has been brought to the open state, contacts are also replaced by electronic switching means before the election is closed.

If the subscriber pressed the hook switch during the transmission of the dialing pulses, to afterwards to establish another more urgent connection, like that

known from DE-OS 23 45 508. There are an anti-bounce circuit and a pulse correction circuit which both work with transistors. The pulse correction circuit has a voltage divider on, after the hook switch contact connecting the line to the telephone set between the speech wires is arranged and on which the base voltage for a dial pulse relay controlling Transistor is removed. This impulse correction

50

it can happen that the election sender has not yet assigned the new connection Sends out stored dialing pulses, since its operating state is maintained by the voltage memory became. This can lead to wrong elections.

The invention is based on the object of a

b5 can be.

The telephones with dialing transmitters are usually provided with "reverse polarity protection", z. B. with a rectifier arrangement. This ensures that the emitter is always connected to the positive Tension lies. The rectifiers used can be used for the monitoring arrangement will.

An npn transistor is to be used if a voice wire with a negative potential is to be monitored and the rectifier g / umzupoIen.

1 sheet of drawings

Claims (2)

Patent claims: 1. Circuit arrangement for monitoring a voice wire for interruption of the supply voltage in telephone sets with a selection transmitter with s voltage memory, characterized in that a voltage divider (R 1, R 2) after which the line to the telephone set connect the hook switch contact is arranged between the voice wires that the base voltage for a transistor ^ 7} is taken from this voltage divider, that its emitter is connected to the speech wire (b) containing the hook switch contact and its collector is connected to the other speech wire (a) via a coil resistor (R 4) , that in this other voice wire a reverse current from the voltage store blocking directional conductor (GIr) is arranged between the connection points of the voltage divider and the collector resistor and that the collector of the transistor (T) with the selector transmitter (WS) for deletion of during the election after the placement of the Handset remaining dialing digits is connected 2. Circuit arrangement according to claim 1, characterized in that between the base and collector of the transistor (T) t \ n capacitor (Cl) is connected.