SU95845A1 - Appliance for checking AC electric calls - Google Patents

Description

This invention relates to instruments for testing the operation of electrical AC calls.

The existing test and measurement table in the ATC (or RTS) cross-country makes it possible, among other basic operations, to check the operation of the call in the subscriber’s telephone by sending a call to the subscriber and polling it from the test table of the station. Such a check does not give satisfactory results due to its pesperity and subjectivity.

The proposed device allows remote testing of the health and relative sensitivity of a call in the subscriber’s office using the visual counting method on a voltmeter scale without the participation of the subscriber or local supervisor.

To accomplish this goal, an AC bridge and a voltage indicator are included in the instrument circuit. An indicator is included in one diagonal of the instrument bridge, and a generator and a line containing a test call are included in the other diagonal.

The drawing shows the electrical circuit of the device, which shows: ringing current generator A, filter F, variable resistance R, blocking capacitor C, rheostatic capacitive bridge M, input transformer Tr, amplifier low frequency U, loudspeaker B and voltmeters Vi and g.

The rheostatic capacitive bridge is connected with a diagonal ab in series to the ringing current circuit and is balanced so that in the diagonal of the ringing current is zero.

The procedure for the work of the Nribor is as follows; generator A, amplifier Y are turned on, resistance R is fully inserted and a subscriber circuit is connected to the input of the device. B. In this case, the ringing current will not be sufficient to drive the bell core, there will be no sound in the speaker B, and the voltmeter Ua will not give readings. Then, the resistance R is gradually outputted and is fixed, at what indications of Vi and Fa voltmeters the sound in the loudspeaker B is shown on the Wits, i.e. the call begins in the subscriber’s unit. By comparing the readings of the Vi and Va voltmeters, the relative sensitivity of the bell is determined.

With a further decrease in the resistance R, as the power of the ringing current and the readings of the voltmeter l / i increase, the volume of the sound in the loudspeaker B and the readings of the voltmeter U increase, indicating an increase in the intensity of the ringer.

For a healthy and normally active call to the established reading of an Vi meter, it must meet certain limits of the reading of the Voltmeter Ug.

AT; the result. Establishing on the scales of voltmeters Vl and Vs dependences of indications - and limits of indications of voltmeters V for normally existing calls, it is possible to make an accelerated check of the serviceability of calls without determining their relative sensitivity.

For this, the rheostat is set to a certain position corresponding to the reading of the Vi voltmeter, then the subscriber lines are alternately connected to the device and only the voltmeter Vs. readings are recorded for each of them.

The V-2 voltmeter readings below the specified limits indicate that a bell needs adjustment.

The absence of sound in loudspeaker B and a zero reading of 1/2 of the voltmeter indicate a malfunction of the call (its measles are not moving).

The performance of checking the serviceability of telephone calls by the proposed device is determined mainly by the speed of alternate switching of the subscriber line to the input of the device.

Subject invention

A device for checking electrical calls of alternating current, tl and h and with the fact that, in order to remotely check the operation of a call and measure its sensitivity, it uses an alternating current bridge and a voltage indicator connected to one of the diagonals of the bridge The other diagonal of which is connected in series to the line containing the test call.