Portable constant-voltage logic hunting instrument

Abstract

The utility model discloses a portable constant voltage logic hunting instrument which comprises a power supply module, a signal processing module, a feedback and indication module and a constant voltage generator module. The power supply module comprises a lithium battery input, a BOOST circuit and a BUCK step-down circuit; the signal processing module comprises a signal receiver, a receiving comparator and a logic judgment device; the feedback and indication module comprises an LED light source and a transceiver; the input of the lithium battery supplies power to the whole equipment, the BOOST circuit supplies power to the logic judgment device, the transceiver and the constant voltage generator, the BUCK circuit supplies power to the LED illumination and the receiving comparator, the input end of the signal receiver is connected to a cable to be tested, the output is transmitted to the receiving comparator and then is output to the logic judgment device, the logic judgment device drives the LED light source and the transceiver, and the LED light source and the transceiver are connected with the signal receiver. The transceiver is connected with the logic judgment device, and the output of the constant voltage generator module is connected with the reference voltage of the comparator. The multi-scene line hunting device is convenient to use and carry, low in cost and high in practicability, and can be used for multi-scene line hunting work.

Description

TECHNICAL FIELD

[0001] The utility model relates to vehicle overhauls auxiliary electrical equipment technical field, concretely relates to a portable constant voltage logic line finder. BACKGROUND

[0002] At present, along with the subway planning is more mature subway quantity also along with year by year to climb, each big city will face the test of the subway vehicle after entering the maintenance period maintenance. Among them, electrical equipment is the control center and information processing center of the vehicle, which is very important for the safe operation of the vehicle, and has the characteristics of numerous, complex cable, difficult to identify, and mutual crossing, which leads to long maintenance period, high error rate and other problems, increasing the cost of subsequent whole vehicle wiring. Therefore, the line finder becomes one of the indispensable tools to determine the correct direction of the vehicle electrical equipment cable. However, the traditional line finder has the following shortcomings: 1. short endurance time, unable to perform repeated charging and discharging; 2. poor environmental adaptability, inconvenient to test in insufficient light; 3. complex structure, high cost.

[0003] The existing line test instrument mainly adopts signal oscillation sounder and signal collector. The line signal oscillator sends audio signal through RJ45 and other general standard interfaces to access the test cable port, ensuring that the test cable loop generates a high-frequency vibration signal. The receiving end adopts a sensitive inductive device to capture the specific signal field in the closed loop, and then completes the on-off detection task of the cable. However, the cable in the electrical cabinet of the subway vehicle has the characteristics of complex and long transmission distance, and the traditional signal oscillation method has large signal attenuation in the long distance transmission process, and the large number of cables at the receiving end cause signal interference, so that the correct cable cannot be accurately determined. SUMMARY

[0004] The utility model discloses to the traditional line finder short endurance time, unable to perform repeated charging and discharging, poor environmental adaptability, inconvenient to test in insufficient light, complex structure, high cost defects, the utility model puts forward a kind of portable constant voltage logic line finder, 3 groups of LED lamp beads are additionally provided on the basis of line calibration function to improve the situation of insufficient light on site, not accurate. It can also be expanded to act as a level logic tester during the communication board card maintenance process, to distinguish the logic state of the board card output in a more direct way.

[0005] The utility model adopts the technical scheme, which is a portable constant voltage logic line finder, comprising a power module, a signal processing module, a feedback and indication module and a constant voltage generator module.

[0006] Preferably, the constant voltage generation end and the receiving end of the constant voltage generator module are designed as pen-shaped structures.

[0007] Preferably, the signal receiver adopts diode clamping before signal acquisition.

[0008] The utility model has the advantages that: (1) the utility model generates constant voltage through the sending end, and then the receiving end collects voltage signals after the measured cable, and the voltage comparator is used to drive the load buzzer or LED, thereby identifying whether the cable ends are connected, and determining the cable line direction, so that the accuracy and efficiency of line calibration are improved. (2) The power supply design part of the utility model expands the typec interface, and can realize the charging and discharging function of the lithium battery, so that the battery can be repeatedly used, the low service life of the button battery and other dry batteries is avoided, and the possibility of environmental pollution is reduced. (3) The signal acquisition circuit of the utility model adopts the triode driving mode to complete the measurement of TTL logic level, and the detection result is more convenient and intuitive compared with the output voltage value of the voltage table. (4) A pair of clamping diodes is designed in the front section of the signal acquisition circuit, and the main purposes are to avoid the floating of the voltage comparator, to prevent the input state from being unknown and to affect the accuracy of detection, to prevent the acquisition voltage from being too high when the table pen is used for logic level testing, and to prevent the circuit from being damaged. In addition, no matter how the table pen is connected to the circuit, the normal operation of the equipment is not affected. (5) The LED light source controls the on-off of three groups of LED lamp beads through independent buttons, so as to improve the insufficient light problem of the subway vehicle in the pit platform operation. BRIEF DESCRIPTION OF DRAWINGS

[0009] Figure 1 The utility model portable constant pressure logic line finder design architecture diagram.

[0010] Figure 2 The utility model portable constant pressure logic line finder overall design drawing. DETAILED DESCRIPTION

[0011] In order to make the purpose, technical scheme and advantage of the utility model embodiment clearer, the technical scheme in the utility model embodiment will be clearly and completely described below in conjunction with the drawings in the utility model embodiment, obviously, the described embodiment is a part of the embodiment of the utility model, not all the embodiment. The components of the utility model embodiment described and shown in the drawing here can be arranged and designed in various different configurations.

[0012] The utility model discloses a novel portable multifunctional line finder, which aims at the combing and wiring work of a large number of signal cables when electrical equipment on the vehicle and under the vehicle is updated during the maintenance of the subway vehicle in the maintenance period, and the vehicle maintenance site is often in the pit track, and the actual harsh working environment problem is that the light is dim. The utility model has the design characteristics of convenient use, convenient carrying, low cost and strong practicability, and can be used for line searching work in multiple scenes.

[0013] The utility model mainly adopts the logic line test instrument of constant voltage output mode, and the design architecture is mainly composed of power module, constant voltage generator, logic judge, LED illumination group and other modules, and the architecture design is as shown in Figure 1 The device power supply adopts the mode of 3.7V lithium battery that can be charged and discharged twice, in order to ensure the normal work of the device, the device has BOOST boost function to increase the voltage to 5V, and BUCK circuit is used to reduce the voltage to 3.3V to ensure the power supply demand of the rear stage. The constant voltage generation end is designed as a pen-shaped structure, mainly containing a voltage follower to generate constant voltage output, the measured cable is connected with the constant voltage output end, and the voltage signal is transmitted to the signal receiver end through the wire. After the signal receiver collects the voltage signal, voltage threshold comparison and voltage logic judgment are carried out, and the judgment result drives the load to realize the identification work of the measured cable.

[0014] As shown in Figure 2 The constant voltage logic line finder mainly includes constant voltage generator, power supply module, signal receiver and other module groups. The constant voltage generator outputs constant voltage signal through the measured cable and the terminal signal receiver, and utilizes the whole vehicle body grounding column to realize the closed loop of the transmission of the receiving and transmitting ends.

[0015] The power module is directly connected to the power supply of the constant voltage generator, logic determinator, receiving comparator and LED light circuit, and the power supply can adopt a lithium battery or typec direct power supply mode. The utility model discloses a U1 as battery charger controller, U1 is a kind of ultra-low power PMU with 2 channels: a 16V single lithium battery linear charger and a 5V voltage booster, and linear charger integrates constant-current constant-voltage control module.At the same time, it also has the pre-charging function of trickle charging for deeply discharged battery, and the fast charging current can be programmed by external resistor.When entering the constant-voltage charging stage, the charging current is reduced to 1 / 10 of the preset value, and the charging will be terminated.The "STAT" pin can also be used to indicate the charging state.The low-power 5V boost converter can provide 0.4A current when the output is 5V.It can be turned off by pulling down ENBST pin, which will disconnect the output of Vbat to further reduce the system standby power.If you want to use typec direct power supply, you can short the reserved 1P2 socket row.U2 is a 3-pin SOT-23A packaged low quiescent current low dropout (LDO) regulator with stable output voltage, and has the protection functions of overcurrent limiting and overheat shutdown, which reduces the 5V voltage output by U1 to 3.3V to provide stable voltage for the subsequent circuit.

[0016] The constant voltage signal generator has the characteristics of high input impedance and low output impedance. The same phase input end of the operational amplifier is connected to the resistance voltage divider, and the output end and the opposite phase input end are directly connected as a voltage follower to generate a stable output voltage value.

[0017] The constant voltage output signal is captured by the signal receiver through the cable to be tested. Before signal acquisition, diode clamping is used, which mainly aims to stabilize the input voltage range and prevent the operational input end from being suspended to cause the unknown state of the pin input, thereby affecting the accuracy of detection. The receiving end detection method mainly uses an operational amplifier to form a threshold voltage comparator, and uses resistance voltage division to preset the threshold voltage. If the collected voltage signal value is greater than the preset threshold value, the operational output high level is amplified by the subsequent NPN triode, and then drives the buzzer to complete the on-off test of the cable. If the collected voltage signal is less than the preset voltage value, the operational amplifier outputs low level signal, and the triode is cut off, which cannot drive the buzzer. The buzzer model is similar to an inductor model. Since the current of the inductor cannot be changed suddenly, a diode is connected in parallel at both ends of the buzzer as a freewheeling function to prevent voltage spikes.

[0018] The voltage signal collected by the signal receiving comparator is used as the input of the voltage comparator and the input of the TTL level logic judge. When the signal input voltage value is less than 0.8V, U5 light emitting diode is turned on, and U6 light emitting diode is turned off; when the signal input voltage value is higher than 2.4V, U5 light emitting diode is turned off, and U6 light emitting diode is turned on, so as to judge the high and low logic level. The LED light source is provided with an independent button, and three groups of LED light sources can improve the working environment under insufficient light conditions.

[0019] The power module is mainly composed of a typec expansion interface and an ETA9697, and can realize secondary charging and discharging of a 3.7V lithium battery. When the voltage on the VIN pin rises to the UVLO threshold value, the ETA9697 starts a charging cycle. A 1% precision R2 resistor needs to be connected between the ISET pin and the ground. If the voltage on the BAT pin is less than 2.9V, the charger will enter the charging mode. In this mode, the charging current is reduced to about 1 / 10 of the threshold value, and the charging process is observed in a more intuitive way through the on-off state of LED1 and LED2. After the charging cycle is terminated, the ETA9697 continuously monitors the voltage of the BAT pin, and when the battery voltage drops below 4.08V, a new charging cycle is started, so that the battery is kept in a fully charged state. The ISET pin output enters a strong pull-down state during the charging cycle. When the KEY1 button is pressed, the EN signal line changes from a low state to a high state, enabling the ETA9697 lithium battery module to charge the lithium battery. Capacitors C3, C4 and C5 mainly have the functions of voltage stabilization and smoothing filtering. In addition, a H1 double-hole pin is reserved, which can be directly used in the typec power supply mode after being short-circuited by a jump cap. If you want to use the typec or lithium battery power supply mode, ensure that KEY1 is invalid.

[0020] When the receiving end Signal signal is high, the transistor is turned on and the diode U6 is lit. The logic judge can also use the same voltage comparator for voltage logic judgment, and can also use the switching characteristics of the transistor for level judgment. In addition, the subway vehicle is usually dim in the A section pit maintenance environment, so three groups of LED lamp beads are expanded, and the current is limited through R9, R11 and R12 resistors to improve the maintenance environment and ensure the safety of the maintenance process and the quality of the maintenance.

[0021] The power provided by typec or lithium battery is used as the input end of the voltage generator, and is input to the same direction input end of the voltage follower after being divided by resistors R8 and R10. The output voltage signal of the voltage follower is captured as the voltage of the voltage comparator through the cable to be detected, and D2 and D3 are used to stabilize the size of the captured voltage signal and prevent the influence of voltage jump on the subsequent circuit. The reverse input end input voltage signal is used as the threshold voltage value after being divided by resistors R14 and R15, and a high level is output when the voltage of the same direction input end is greater than the reverse preset threshold voltage value, and a low level is output when the voltage of the reverse input end is greater than the voltage of the same direction input end. When the voltage comparator outputs a high level, the buzzer in the subsequent stage is actuated. The buzzer is similar to an inductor model. Since the inductor current cannot be suddenly changed, when the MOS tube is turned off, the inductor current has no freewheeling circuit, which may cause the voltage across the MOS tube to suddenly change, and when the voltage value is higher than the rated voltage value, the MOS tube may be broken. Therefore, a freewheeling diode is connected in parallel across the buzzer to provide a freewheeling circuit, thereby reducing the risk of MOS breakdown.

[0022] The basic principle and main features of the utility model and the advantages of the utility model are shown and described above. It should be understood by those skilled in the art that the utility model is not limited by the above-mentioned embodiments, and the above-mentioned embodiments and the description in the specification are only used to illustrate the principle of the utility model. Without departing from the spirit and scope of the utility model, the utility model can also have various changes and improvements, and these changes and improvements all fall within the scope of the utility model claimed. The scope of protection of the utility model is defined by the appended claims and their equivalents.

Claims

1. A portable constant-voltage logic line tracer, characterized by: It comprises power module, signal processing module, feedback and indication module, constant voltage generator module; the power module comprises lithium battery input, BOOST boost circuit, BUCK buck circuit; the signal processing module comprises signal receiver, receiving comparator, logic judge; the feedback and indication module comprises LED light source and transceiver; the lithium battery input supplies power for the whole device, the BOOST boost circuit boosts the 3.7V voltage of the lithium battery input to 5V to supply power for the logic judge, the transceiver and the constant voltage generator, the input of the BUCK buck circuit is the output of the BOOST boost circuit, the output voltage 5V is reduced to 3.3V to supply power for the LED lighting and the receiving comparator, the input end of the signal receiver is connected to the cable to be measured, the output is transmitted to the receiving comparator and then output to the logic judge, the output control signal of the logic judge drives the LED light source and the transceiver, the transceiver is connected with the logic judge through a serial port, and the reference voltage of the constant voltage generator module is connected with the receiving comparator.

2. The portable constant-voltage logic line tracer of claim 1, wherein: The constant voltage generation end and the receiving end of the constant voltage generator module are designed as pen-shaped structures.

3. The portable constant-voltage logic line tracer of claim 1, wherein: The signal receiver adopts diode clamping before signal acquisition.

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