SU472477A1 - Calling device - Google Patents

Description

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The invention relates to telephone communication, in particular, to devices for sending Ringing Tones and can be used primarily in quasi-electronic and electronic type exchanges, as well as in other automatic switching systems.

A device for sending call signals is known, which contains a power transformer, one of the ends of whose windings is connected to the talk wires, and the others respectively to the power source and the response signal receiving unit, and a key circuit.

The purpose of the invention is to increase the noise immunity and reliability of the device.

This is achieved by introducing a trigger on transistors, the collectors of which are connected to the ends of the additional winding of the supply transformer, and the emitters of the transistors are connected to ground through a key circuit, the middle point of the additional winding of the trans (|) ormatrar connected to one of the poles. power source.

The drawing shows a functional diagram of the proposed device to send a call signal.

The device for sending the call signal contains a power transformer with windings 1, 2, 3, subscriber response scheme 4, a trigger on transistors 5, 6 and resistors 7, 8. The negative pole of the power source, Ek, is connected to the midpoint of the auxiliary winding 3.

The trigger is controlled by applying the ground potential to the emitters of the transistors through the key circuit 9, which is unlocked by control signals received via the wire 10. These signals determine the duration of the call and the duration of the pauses between the messages. The subscriber response indication is output from the subscriber 4 response scheme over wire 11.

The device works as follows.

The trigger produces a voltage that is close to a sinusoidal frequency in the order of 25 Hz, which is transformed into a linear winding.

In the initial state, the control signal through the wire 10 is not received, the key circuit 9 is locked and the trigger does not work. The trigger is energized after the triggering signal is applied over the wire 10 to the key circuit 9.

The generated call voltage is transformed into windings 1, 2 and through the line enters the device. The duration of a parcel is determined by the open state time of the key circuit 9.

When the subscriber answers while making a call, the resistance of the telephone apparatus decreases dramatically, the resistance converted to the winding 3 also decreases and the generation fails.

Due to the flow of the constant component of the current through the closed loop of the subscriber line, the response circuit of the subscriber 4 forms a response signal on the wire 11. Since, after the response, the generation fails spontaneously, the response circuit is greatly simplified and represents an ordinary transistor switch that opens after the subscriber answers. The subscriber answer mark appearing on wire 11 is best used during the pause between shipments, and thus the influence of the variable component on the response scheme is deleted.

Subject invention

The device for sending call signals, mainly for electronic and quasi-electronic automatic switching systems, contains a power transformer, one of which ends the windings of which are connected to the speaker wires, and the other respectively to the power supply and the response signal receiving unit, and the purpose of increasing the stability and reliability of the device, it introduced a trigger on the transistors, the collectors of which are connected to the ends of the additional winding of the supply transformer, the emitters of the transistors are connected to ground via a key scheme, wherein the midpoint of the transformer is connected to the auxiliary winding from the power source odiomu poles.