KR920002205B1 - Test signal generating circuit in electronic exchange - Google Patents

Abstract

The generator for generating test call signalto test a subscriber's circuit has a reduced size. The generator comprises a pulse generator for generating call signal having constant period, an amplifier for amplifying the call signal to have a designated amplitude, an input filter for eliminating the noise incoming through input terminal, a voltage level changing unit for changing the level of input voltage, and a power supply for rectifying and filtering the level changed voltage to provide power to the pulse generator and the amplifier.

Description

Test call signal generation circuit in electronic switching system

1 is a conventional circuit diagram.

2 is a circuit diagram of the present invention.

3 is an operational waveform diagram for each part of FIG.

* Explanation of symbols for main parts of the drawings

PT1, PT2: Transformers Q1, Q2: Transistor

G1: inverting element 200: timer

221, 222: filter coil circuit 231: regulator

L1-L3: Coil CR1-CR20: Diode

C1-C8: Capacitor R1-R13: Resistance

The present invention relates to an apparatus for testing a subscriber circuit in an electronic switching system, and more particularly to a circuit for supplying a test call signal to a subscriber.

The general existing electronic switching system has a function of self-testing subscriber circuits, and performs a subscriber circuit test apparatus for generating various test signals to perform the subscriber circuit self-test function, and relays subscriber circuits with the subscriber circuit test apparatus. And a test bench matching device. The call signal generation circuit is configured separately from the subscriber circuit test apparatus to supply a call signal to the subscriber circuit and to supply a call signal to the common ring bus line of the subscriber circuit test apparatus.

The call signal generation circuit is mounted in a ring supply device of a conventional electronic switching system, and in the related art, the linking oscillation unit 110, the voltage follower 120, the alarm circuit unit 160, and the thermal protection unit ( 140, the overvoltage protection unit 150, and the output amplifier 130. The linking oscillator 110 supplies a sine waveform of the linking signal.

This circuit section uses a power plant called the XR-8038 to create continuous oscillation.

The voltage follower 120 buffers the signal generated by the linking oscillator 110 and amplifies and rectifies the signal with a single gain. The voltage follower 120 outputs the amplified and refined ringing signal to the output amplifier 130. And to the alarm circuit unit 160.

The output amplifier 130 amplifies the signal output from the voltage follower 120 into a signal voltage for supplying the subscriber, and also removes noise included in the signal amplified at the front end.

The overheat protection unit 140 and the overvoltage protection unit 150 serve to prevent overvoltage input or inverted input to the entire circuit and to prevent overheating of the entire circuit.

The alarm circuit unit 160 detects an abnormal state and performs a function of displaying the detected abnormal state through a light emitting device (LED) so that a user can know the detected abnormal state. Types of abnormal conditions include overvoltage and supply input voltage when an error occurs in the output generated by the prescribed linking output. The output transformer PT performs a relay role for transmitting the output of the output amplifier 130 to the subscriber matching device through the common ring bus line of the subscriber circuit tester.

The two switches SW1 and SW2 are used to select the voltage width of the call signal output to the common ring bus line of the subscriber circuit tester to have one of 155V or 110V, and the variable resistor VR1 sets the frequency of the ringing signal. The variable resistor VR2 is used to adjust the amplitude of the ringing signal supplied to the output amplifier 130.

However, although the conventional call signal supply circuits have various functions, they are difficult to be mounted in a small area due to the large circuit volume, and many devices are difficult to obtain. Also, a device having a small capacity and low power call signal, such as a subscriber circuit test apparatus, and In a situation such as when the power margin of the device is not much, a lot of power is consumed, there is a problem that is difficult to use.

Accordingly, an object of the present invention is to provide a call signal generation circuit having a simple circuit configuration of small capacity and low power so that it can be embedded in and operated in a subscriber circuit test apparatus in an electronic switching system.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. 2 is a circuit diagram of the present invention, in which pulse generating means comprising two variable resistors R10 and R11, a capacitor C17, and a timer 200 for generating a call signal waveform of a predetermined period, Amplifying means comprising an inverting element (G1), two resistors (R12, R13), and transistors (Q1, Q2) for amplifying the call signal generated by the amplifier to have an amplitude of a predetermined magnitude, and externally through an input terminal (IP). Input filter means composed of diode DR1 and coil L1 and four condensers C1-C4 and a power supply input through the input filter means are required to remove noise included in the supply power supplied from the same. A voltage change means consisting of a transformer PT1, two diodes CR2 and CR3, a capacitor C5, and two resistors R1 and R2 to convert the voltage at a voltage level, Rectify and filter the pulse Water stage and for supplying the amplifying means is composed of the power supply means consisting of the 1-3 rectification filter section (200 230 240).

3 is an operational waveform diagram for each part of FIG.

Accordingly, the present invention will be described in detail with reference to FIGS. 2 and 3. The input filter part is composed of a filter circuit composed of a coil L1 and a capacitor C1 and energy storage capacitors C2, C3, and C4. The energy storage capacitor allows the transformer (PT1) to be provided with a low impedance source to the power supply by them. In addition, the filter circuit consisting of the coil (L1) and condenser (C1) provides power input from an external power transformer. The power is filtered to maintain a constant power supply by making it a smooth, constant voltage.

The voltage converting means is composed of one transformer PT1 and two diodes CR2 and CR3.

When the diode CR3 is inputted with the inverted nationality to the power input line, a large blow is applied to the entire circuit. To prevent this, the diode CR3 is connected in a reverse direction to the input voltage to turn on the diode CR3. It becomes a (ON) state and acts as a large-capacity rectifier that blocks the input from being transmitted to the next stage in a circuit. The transformer consists of the first and second windings L11 and L12 on the primary side, and the first winding and the second winding. The diode CR2 is connected to one terminal of the winding to perform the same function as the diode CR3, thereby preventing the transformer PT1 from being destroyed by overvoltage.

The transformer PT1 has a turns ratio configured to convert the filtered -48V input to the primary winding into the power required by the circuit (+ 5V, -12V, + 12V). The outputs of the windings L21-L24 are respectively used as the desired power supply through the rectifier circuit.

+ 5V uses two secondary 3rd and 4th (L23, L24) windings, so that even if the power conversion is large, the current is divided and converted, thereby improving heat dissipation to heat. The output from the power conversion means is input to each of the 1-3 rectifier filter units 220, 230, and 240.

The first rectifying filter unit 220 is composed of two circuit groups, and two filter coil circuits 221 and 222 of these circuit groups are used to divide a current between the rectifying circuits. Four output capacitors (C8-C10) are also used to minimize the ripple current.

The output diodes CR12, 13, 14, 15 prevent the power supply from inverting in the reverse direction so that the enhancement + 5V can be maintained. The capacitor C12 forms a bypass between + 5V and ground.

In the second and third rectifying filter sections 230 and 240, two three-terminal regulators 241 and 231 are always used to supply a uniform output. These circuit groups filter the voltage from the power conversion means by filter circuits L2, L3, C13, and C15 consisting of coil-capacitors, and allow the two regulators 231 and 241 to make a good output.

The diodes CR18 and CR21 form a protection path for the circuit to be improved and protected by acting to connect the two regulators as inputs to the overvoltage when an overvoltage occurs.

The second and third rectifier filter units 230 and 240 have designed peripheral parameters to supply a voltage within 15V of an enhancement when a load is present.

The pulse generating means is a part which plays the same role as the ringing oscillation unit in the existing call signal generating circuit and continuously oscillates at the pulse period determined by the following equation by the values of the two variable resistors R10 and R11.

The external capacitor C17 is charged with current through the variable two resistors R10 + R11 and discharged through the variable resistor R11. During charging, the TRIC input of the timer 200 connected to the prus terminal of the capacitor C13 is charged. The timer 200 stops operation because no current is supplied to the capacitor. The capacitor C17 starts discharging through the variable resistor R11, and current is supplied to the TRIG input of the timer 200. The timer 200 is operated.

The capacitor C10 charges and discharges between 1/3 and 2/3 of the power supply.

Also, the charge and discharge times are independent of the power supply. The charge time (output high) is given by

And discharge time (output low)

Therefore, the total cycle is

to be.

The output of the pulse generating means portion is supplied to the amplifying means, and the amplifying means is composed of two transistors Q1 and Q2 in a push-pull relationship.

The inverting element G1 inverts the output of the pulse generating means and supplies it to the transistor Q1, and the transistor Q2 receives the output of the pulse generating means directly. Therefore, when the transistor Q1 is in the ON state, The transistor Q2 is turned off, so that the two transistors Q1 and Q2 always perform opposite operations.

The output of the amplifying means is supplied across the primary winding of the output transformer PT2. The middle tap of the primary winding of the output transformer PT2 is fed to the -12V by the second rectifying filter section 230. When the input is input to either of the primary taps, that is, when one of the two transistors (Q1, Q2) of the amplifying means is on-phase, the collector input of the transistor (-12V) is turned on. Will be supplied. Therefore, the current flowing through the primary winding causes the secondary winding of the output transformer PT2 to be induced with the current so that the waveform we desire can be obtained.

In addition, since the secondary winding is supported by the filtered -48V of the input filter unit, the output forms a triangular wave based on -48V. At this time, the output waveform of the timer 200 of the pulse generating means is shown in FIG. 3, 300, the output waveform of the inverting element G1 is shown in FIG. 3, 301, and the output waveform of the transistor Q1 is shown in FIG. As shown in FIG. 3, the output waveform of the transistor Q2 is shown in FIG. 303, and the output waveform of the output transformer PT2 is shown in FIG.

As described above, the present invention can generate a small call signal and supply it to the subscriber matching device through the subscriber circuit test apparatus, and also simplify the circuit and reduce the power consumption and the advantage of being mounted in the subscriber circuit test apparatus. There is an advantage.

Claims (1)

An electronic switching system comprising a subscriber matching device and a subscriber circuit testing device, comprising: pulse generating means for generating a call signal waveform of a predetermined period and amplifying the call signal generated by the pulse generating means to have an amplitude having a predetermined magnitude; A power supply for converting a voltage at a voltage level that requires an amplifying means, an input filter means for removing noise included in a supply power supplied from the outside through an input terminal IP, and a supply power input through the input filter means. And means for changing, and outputting the means, rectifying and filtering the power supply means for supplying the pulse generating means and the amplifying means to generate a low capacity call signal and supply the subscriber matching device through the subscriber circuit test apparatus. Test call signal generation circuit.

Images