Signal transmitting circuit, transmitter, and cable detector used in cable detectors

Abstract

This utility model discloses a signal transmitting circuit, transmitter, and cable detector for use in cable detectors. The signal transmitting circuit includes a signal amplification circuit and an output protection circuit. The signal amplification circuit includes a motor driver chip with an H-bridge circuit. The H-bridge circuit amplifies the alternating signal provided by the signal source through a single stage. The output protection circuit transmits the alternating signal output by the signal amplification circuit while preventing the signal amplification circuit from burning out. Therefore, implementing this utility model can amplify the alternating signal through the H-bridge circuit in the motor driver chip, reducing the design complexity and production / deployment costs of the signal transmitting circuit used in cable detectors. By replacing the traditional multi-stage operational amplifier architecture, it can improve the output current driving capability, enhance the penetration strength of the transmitted signal in the soil medium, expand the effective detection depth and detection distance of underground cables, and improve the accuracy of detecting and locating deeply buried cables.

Description

Technical Field

[0001] This utility model relates to the field of cable detector technology, and in particular to a signal transmitting circuit, transmitter and cable detector used in cable detectors. Background Technology

[0002] In the power, telecommunications, and construction sectors, accurate location and fault detection of underground cables are core requirements for operation and maintenance. As a critical tool, the performance of the signal transmission circuit of a cable detector directly affects its detection range and anti-interference capability.

[0003] Currently, most existing signal transmission circuits use linear amplifiers to amplify the original transmitted signal, such as operational amplifiers or transistor current amplification. However, in practice, it has been found that to achieve sufficient signal gain, using linear amplifiers requires a multi-stage cascaded operational amplifier design, which leads to relatively high circuit design complexity and necessitates repeated impedance matching during debugging, which is not conducive to the use of cable detectors.

[0004] Therefore, it is particularly important to reduce the design complexity of the signal transmission circuit used in cable detectors. Utility Model Content

[0005] This invention provides a signal transmitting circuit, transmitter, and cable detector for use in cable detectors, which can reduce the design complexity of the signal transmitting circuit for use in cable detectors.

[0006] To solve the above-mentioned technical problems, the first aspect of this utility model discloses a signal transmitting circuit for a cable detector, the signal transmitting circuit including a signal amplification circuit and an output protection circuit;

[0007] The signal amplification circuit includes a motor driver chip, which has an H-bridge circuit. The motor driver chip is electrically connected to a signal source and is used to amplify the alternating signal provided by the signal source through the H-bridge circuit.

[0008] The output protection circuit is electrically connected to the signal amplification circuit and is used to transmit the alternating signal output by the signal amplification circuit, while preventing the signal amplification circuit from burning out.

[0009] As an optional implementation, in the first aspect of this invention, the alternating signal provided by the signal source is an SPWM signal or a PWM signal.

[0010] As an optional implementation, in the first aspect of this utility model, the signal amplification circuit further includes a drive filtering module, which is electrically connected to the motor drive chip and is used to provide filtered power to the motor drive chip.

[0011] As an optional implementation, in the first aspect of this utility model, the signal transmitting circuit further includes a transformer-conversion circuit, the two ends of which are electrically connected to the signal amplification circuit and the output protection circuit, respectively. The transformer-conversion circuit is used to perform secondary amplification on the alternating signal after primary amplification and output it to the output protection circuit.

[0012] As an optional implementation, in the first aspect of this utility model, the transformer conversion circuit includes a transformer and a transformer protection module;

[0013] The transformer is electrically connected to the output protection circuit, and the transformer is used to perform two-stage amplification processing on the alternating signal;

[0014] The two ends of the transformer protection module are electrically connected to the signal amplification circuit and the transformer, respectively, to prevent the reverse electromotive force generated by the transformer from damaging the signal amplification circuit.

[0015] As an optional implementation, in the first aspect of this utility model, the output protection circuit includes a fuse and a transient voltage suppressor;

[0016] The fuse is electrically connected to the signal amplification circuit to prevent the signal amplification circuit from burning out.

[0017] The transient voltage suppressor is electrically connected to the signal amplification circuit and is used to absorb surge voltage.

[0018] The second aspect of this utility model discloses a transmitter for a cable detector. The transmitter includes a transmitter body, a signal source module disposed on the transmitter body, and a signal transmitting circuit as disclosed in the first aspect of this utility model disposed in the transmitter body. The signal source module is electrically connected to the signal transmitting circuit and is used to provide an alternating signal to the signal transmitting circuit.

[0019] As an optional implementation, in the second aspect of this utility model, the signal source module includes an MCU module.

[0020] As an optional implementation, in a second aspect of the present invention, the transmitter further includes a voltage detection circuit disposed in the transmitter body, the voltage detection circuit being electrically connected to the signal source module and the cable to be tested respectively, and the voltage detection circuit being used to detect the voltage in the cable to be tested.

[0021] The third aspect of this utility model discloses a cable detector, including a receiver and a transmitter as disclosed in the second aspect of this utility model, wherein the receiver is used to receive signals emitted by the transmitter for cable detection.

[0022] Compared with the prior art, the embodiments of this utility model have the following beneficial effects:

[0023] 1. The signal transmitting circuit provided by this utility model, by setting a signal amplification circuit and an output protection circuit, includes a motor driver chip with a built-in H-bridge circuit. During signal transmission, the alternating signal can be directly amplified through the H-bridge circuit, and the signal is transmitted through the output protection circuit. Compared with the multi-stage operational amplifier circuit in traditional solutions, the design complexity and production and debugging costs of the circuit are greatly reduced. At the same time, by directly amplifying the signal through the motor driver chip, replacing the traditional multi-stage operational amplifier architecture, the driving capability of the output current can be improved, and the penetration strength of the transmitted signal in the soil medium can be enhanced, thereby expanding the effective detection depth and detection distance when detecting underground cables and improving the detection and positioning accuracy of deeply buried cables. In addition, the output protection circuit can withstand the transient high voltage generated by live operation, thereby avoiding the burnout of core components and improving the robustness of the equipment in complex power grid environments.

[0024] 2. The transmitter provided by this utility model reduces the production and debugging costs of the transmitter itself by using a signal transmission circuit with low circuit design complexity and low production and debugging costs, high signal transmission penetration strength and good robustness in complex power grid environments. At the same time, it can improve the signal penetration strength and service life of the transmitter.

[0025] 3. The cable detector provided by this utility model uses a transmitter with low production and debugging costs, high signal penetration strength and long service life, which greatly reduces the production and debugging costs of the cable detector. At the same time, it can improve the effective detection depth, detection distance and detection positioning accuracy of the cable detector and the service life of the cable detector itself, which is conducive to the widespread application of the cable detector. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the structure of a signal transmitting circuit for a cable detector disclosed in an embodiment of this utility model;

[0028] Figure 2 This is a schematic diagram of the structure of a signal amplification circuit disclosed in an embodiment of this utility model;

[0029] Figure 3This is a schematic diagram of the structure of a transformer-conversion circuit disclosed in an embodiment of this utility model;

[0030] Figure 4 This is a schematic diagram of the structure of an output protection circuit disclosed in an embodiment of this utility model;

[0031] Figure 5 This is a schematic diagram of the structure of a cable detector disclosed in an embodiment of this utility model;

[0032] Figure 6 This is a schematic diagram of the structure of a voltage detection circuit disclosed in an embodiment of this utility model. Detailed Implementation

[0033] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0034] It should be noted that, unless otherwise expressly specified and limited, the term "electrical connection" in the specification, claims, and accompanying drawings of this utility model should be interpreted broadly. For example, it can be a fixed electrical connection, a detachable electrical connection, or an integral electrical connection; it can be a mechanical electrical connection, an electrical connection, or a connection that allows for communication; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two elements or an interaction between two elements. Furthermore, the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this utility model are used to distinguish different objects, not to describe a specific order. The terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0035] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the present invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0036] This utility model discloses a signal transmitting circuit, transmitter, and cable detector for use in cable detectors. The signal transmitting circuit provided by this utility model incorporates a signal amplification circuit and an output protection circuit. The signal amplification circuit includes a motor driver chip with a built-in H-bridge circuit. During signal transmission, the alternating signal can be directly amplified through the H-bridge circuit, and the signal is transmitted through the output protection circuit. Compared with the multi-stage operational amplifier circuit in traditional solutions, the design complexity and production and debugging costs of the circuit are significantly reduced. Furthermore, by directly amplifying the signal through the motor driver chip, replacing the traditional multi-stage operational amplifier architecture, the driving capability of the output current is improved, enhancing the penetration strength of the transmitted signal in the soil medium. This expands the effective detection depth and distance for underground cable detection, improving the accuracy of detection and positioning of deeply buried cables. In addition, the output protection circuit can withstand transient high voltage generated by live operation, thus preventing the burnout of core components and improving the robustness of the equipment in complex power grid environments.

[0037] The transmitter provided by this utility model reduces the production and debugging costs of the transmitter itself by using a signal transmission circuit with low circuit design complexity and low production and debugging costs, high signal transmission penetration strength, and good robustness in complex power grid environments. At the same time, it can improve the signal penetration strength and service life of the transmitter.

[0038] The cable detector provided by this utility model significantly reduces production and debugging costs by using a transmitter with low production and debugging costs, high signal penetration strength, and long service life. Simultaneously, it improves the effective detection depth, detection distance, and accuracy of cable detection and positioning, as well as the service life of the cable detector itself, thus facilitating its widespread application. Detailed explanations follow.

[0039] Example 1

[0040] Please see Figure 1 , Figure 1 This is a schematic diagram of the structure of a signal transmitting circuit used in a cable detector, as disclosed in an embodiment of this utility model. Figure 1 The described signal transmitting circuit for a cable detector can be applied to cable testing equipment, including a cable detector, and can also be applied to intelligent devices associated with the cable testing equipment. These intelligent devices include, but are not limited to, one or more of the following: switching equipment, cloud equipment, edge computing equipment, relay equipment, base station equipment, urban management equipment, and intelligent connected devices. This utility model embodiment does not limit the application of these devices. Figure 1 As shown, the signal transmitting circuit used in the cable detector may include a signal amplification circuit 10 and an output protection circuit 20;

[0041] The signal amplification circuit 10 includes a motor driver chip 101, which is equipped with an H-bridge circuit. The motor driver chip 101 is electrically connected to the signal source and is used to amplify the alternating signal provided by the signal source through the H-bridge circuit.

[0042] The output protection circuit 20 is electrically connected to the signal amplifier circuit 10 and is used to transmit the alternating signal output by the signal amplifier circuit 10, while preventing the signal amplifier circuit 10 from burning out.

[0043] In this embodiment of the present invention, the motor drive chip may include, but is not limited to, DRV8870, L298N, etc. The motor drive chip integrates an H-bridge circuit, that is, four power switches (such as MOSFETs or IGBTs) forming an H-bridge topology. The input pins of the chip are directly electrically connected to the output pins of the signal source (such as a microcontroller) to receive alternating signals (such as PWM signals).

[0044] The H-bridge circuit works as follows: It amplifies the input signal by controlling the on / off states of four switches. Specifically, when the signal source outputs a high level, the upper left and lower right switches of the H-bridge are turned on, and current flows from the positive terminal of the power supply to the load (output terminal). When the signal source outputs a low level, the upper right and lower left switches of the H-bridge are turned on, and current flows in the reverse direction, thus generating an amplified alternating output signal. This process is called "first-stage amplification," and its function is to amplify low-power signals (such as milliwatt-level signals from an MCU) to watt-level signals, improving signal strength and driving capability, enabling effective coupling into the cable.

[0045] The signal source is connected to the input pin of the motor driver chip, and the output pin of the chip is connected to subsequent circuits (such as output protection circuits). The power supply provides power to the motor driver chip and supports its switching operation.

[0046] Using a motor driver chip in the transmitter of a cable detector leverages the H-bridge output capability of the motor driver chip to better amplify the alternating current signal, i.e., the transmitted signal, and offers the following advantages:

[0047] High efficiency: Compared to traditional linear amplifiers, such as those using operational amplifiers or transistors to amplify current, the PWM-driven H-bridge operates in a switching state and has extremely low power consumption. This means that less battery power is converted into heat and more energy is used to generate a magnetic field, thereby extending the device's lifespan.

[0048] Integrated protection: The chip has built-in overcurrent protection, overtemperature protection, undervoltage lockout and other functions, which can prevent damage to the equipment due to short circuit, overload or low battery voltage, and greatly improve the reliability of the system.

[0049] Simplified design: A complete power amplifier system can be built with just one chip and a few external components (capacitors, sampling resistors), which is simpler, more compact and more reliable than building amplifier circuits with discrete MOSFETs;

[0050] Easy to control: It can be controlled directly using the MCU's digital signals, without the need for complex analog circuit design;

[0051] Furthermore, optionally, for the output protection circuit, it can be directly electrically connected to the output terminal of the signal amplification circuit, and optionally, it consists of one or more fuses and / or capacitors in series, and a transient suppression element (such as a TVS diode) in parallel.

[0052] The amplified alternating signal is first transmitted to the output terminal (e.g., the probe of the connecting cable) through a fuse. The fuse blows in case of abnormal current (such as a short circuit), cutting off the circuit and preventing large current from damaging the signal amplification circuit. Simultaneously, transient suppression components absorb voltage spikes (such as switching noise or external surges), ensuring that the switching elements of the signal amplification circuit are not burned out by overvoltage. Its function is to provide overcurrent and overvoltage protection while transmitting the signal, improving circuit reliability.

[0053] In summary, the overall execution logic is as follows: the signal source generates an alternating signal, which is input to the signal amplification circuit; the H-bridge performs switching amplification and outputs an amplified signal; the output protection circuit monitors for abnormalities during signal transmission and triggers the protection mechanism in case of a fault. In implementation, all connections are achieved through PCB routing to ensure low-impedance paths and reduce losses.

[0054] As can be seen, implementing this utility model embodiment can amplify alternating signals through the H-bridge circuit in the motor driver chip, eliminating the need for multi-stage operational amplifiers and compensation circuits in traditional solutions, thus reducing the design complexity and production and debugging costs of the signal transmission circuit applied to cable detectors. Simultaneously, by directly amplifying the signal through the motor driver chip, replacing the traditional multi-stage operational amplifier architecture, the output current driving capability can be improved, enhancing the penetration strength of the transmitted signal in the soil medium, expanding the effective detection depth and distance of underground cables, and improving the detection and positioning accuracy of deeply buried cables. Furthermore, combined with the output protection circuit, it can withstand transient high voltages generated by live operation, thereby preventing the burnout of core components and improving the robustness of the equipment in complex power grid environments.

[0055] In this embodiment of the present invention, as an optional implementation, the alternating signal provided by the signal source is an SPWM signal or a PWM signal.

[0056] In this optional embodiment, the signal source can be a programmable device (such as a microcontroller MCU) that generates a specific type of alternating signal. The SPWM (sine wave pulse width modulation) signal is generated by an internal timer of the MCU. The logic is that the MCU calculates the sampling points of the sine wave and outputs a series of pulses with varying widths (the duty cycle varies with the sine function), thereby approximating a sine wave after filtering.

[0057] Furthermore, the signal source and the motor chip are connected via two signal lines to transmit complementary PWM signals or complementary SPWM signals. Taking complementary PWM signals as an example, the complementary PWM signals are generated by the MCU into two PWM signals with opposite phases (for example, one signal is high when the other is low), and dead-time control is used to avoid short circuits.

[0058] Optional signal function: SPWM signals are suitable for applications requiring low harmonic distortion, reducing electromagnetic interference. Furthermore, SPWM signals offer higher recognition accuracy, making them ideal for precise identification of target cables in densely populated areas. PWM signals also possess strong power drive capability and good signal penetration, making them suitable for long-distance detection, enabling simple path tracing and fault location. In implementation, the signal is output to the input pin of the motor driver chip via the MCU's GPIO pins. The signal frequency is typically adjustable within the range of 1kHz-100kHz to adapt to different cable detection requirements.

[0059] In summary, the overall logic is as follows: the MCU generates a signal based on preset parameters (such as frequency and amplitude), which serves as the input source for the amplifier circuit. The choice between SPWM and PWM signals depends on the system design; SPWM can be used for high-quality signal transmission, while complementary PWM can simplify the drive logic.

[0060] As can be seen, implementing this optional embodiment, by employing an SPWM (Sine Wave Pulse Width Modulation) signal, can generate a smooth, approximately sinusoidal waveform, significantly reducing high-order harmonic components, thereby reducing electromagnetic interference, preventing the detection signal from being submerged by environmental noise, and improving signal purity. SPWM signals are characterized by low harmonic content and flexible control, while PWM signals have strong power drive capability and good signal penetration, making them suitable for long-distance detection. In summary, this optional embodiment can optimize waveform quality and reduce interference by flexibly selecting SPWM or PWM signals, thereby improving the noise immunity and adaptability of the detection signal, and ultimately enhancing cable positioning accuracy and equipment scene coverage.

[0061] In this embodiment of the utility model, as another optional implementation method, such as Figure 2 As shown, Figure 2This is a schematic diagram of a signal amplification circuit disclosed in an embodiment of the present utility model. The signal amplification circuit 10 also includes a drive filter module 102, which is electrically connected to the motor drive chip 101 and is used to provide filtered power to the motor drive chip 101.

[0062] like Figure 2 As shown in the figure, the main component is the motor driver chip 101, which integrates an H-bridge circuit. The functions of its key pins are as follows:

[0063] VM: Power input terminal, connected to +30V, to power the power switching transistors of the H-bridge;

[0064] VREF: Logic reference voltage terminal, connected to +3.3V, providing a reference for the internal logic circuits of the chip;

[0065] OUT1 / OUT2: H-bridge output terminals, which can be electrically connected to the output protection circuit;

[0066] ISEN: Current sensing terminal, used to monitor the output current;

[0067] IN1 / IN2: Control input terminals, receiving PWM signals from the signal source to drive the H-bridge switch;

[0068] Further, optionally, the drive filter module 102 may include a decoupling capacitor C1, a filter capacitor C2, a filter capacitor C3, and a current sensing resistor R1.

[0069] C1 can filter out high-frequency noise from the logic power supply (+3.3V), stabilize the VREF reference voltage, and ensure the stability of the chip's logic control.

[0070] C2 can filter out high-frequency spike noise from the power supply (+30V), and together with C3, it can achieve wideband filtering.

[0071] C3 can filter out low-frequency ripple from the power supply (+30V), and together with C2, it provides a clean power supply for the motor drive chip.

[0072] R1 can be used as a current sensing resistor to monitor the output current through the ISEN pin, triggering overcurrent protection to prevent the chip from burning out.

[0073] It should be noted that in practical applications, the number of corresponding components can be increased or decreased adaptively, and in order to further improve the effect of the corresponding components, the components can be connected in series or parallel. In this regard, the present invention does not make specific limitations.

[0074] It is evident that implementing this utility model embodiment can purify the power input through the drive filter module, improve the stability and reliability of the signal amplification circuit, thereby optimizing the output signal quality and enhancing the anti-interference capability of the cable detector in complex electromagnetic environments.

[0075] In this embodiment of the utility model, as another optional implementation method, such as Figure 3 As shown, Figure 3 This is a schematic diagram of a transformer-conversion circuit disclosed in an embodiment of the present utility model. The signal transmitting circuit mentioned above also includes a transformer-conversion circuit 30. The two ends of the transformer-conversion circuit 30 are electrically connected to the signal amplification circuit 10 and the output protection circuit 20, respectively. The transformer-conversion circuit 30 is used to perform secondary amplification on the alternating signal after primary amplification and output it to the output protection circuit 20.

[0076] In this optional embodiment, the transformer circuit is optionally located between the signal amplification circuit and the output protection circuit. It consists of a transformer (such as a ferrite core transformer), with the primary coil connected to the output of the signal amplification circuit and the secondary coil connected to the output protection circuit. The transformer is designed as a step-up type (e.g., turns ratio 1:2) to further amplify the voltage.

[0077] When the alternating signal (from the H-bridge output) after the first stage of amplification is input to the primary coil of the transformer, the transformer generates a higher voltage or current signal in the secondary coil through the principle of electromagnetic induction (second stage amplification). For example, if the first stage output is 12V peak-to-peak, the second stage amplification can boost it to 24V peak-to-peak, enhancing the signal penetration capability. The amplified signal is then directly transmitted to the output protection circuit.

[0078] The signal amplitude is increased through a two-stage amplification process using a transformer conversion circuit, making it more suitable for long-distance transmission or generating a strong electromagnetic field in metal cables, thereby improving the detection range and sensitivity. In implementation, a high-frequency transformer is selected (operating frequency matched to the signal source) to minimize losses.

[0079] As can be seen, implementing this optional embodiment can achieve secondary signal boosting through the transformer conversion circuit, breaking through the power bottleneck of single-stage amplification, thereby enhancing signal penetration and detection distance, and thus improving the accuracy and comprehensiveness of deep-buried cable positioning.

[0080] In this optional embodiment, as an optional implementation method, such as Figure 3 As shown, the above-mentioned transformer conversion circuit 30 includes a transformer 301 and a transformer protection module 302;

[0081] Transformer 301 is electrically connected to output protection circuit 20. Transformer 301 is used to perform two-stage amplification of alternating signals.

[0082] The two ends of the transformer protection module 302 are electrically connected to the signal amplification circuit 10 and the transformer 301, respectively, to prevent the reverse electromotive force generated by the transformer 301 from damaging the signal amplification circuit 10.

[0083] Furthermore, such as Figure 3 As shown, optionally, the above-mentioned transformer 301 is... Figure 3 TR1 in the above-mentioned transformer protection module can specifically include a bidirectional transient suppression diode D1, parallel capacitors C4 and C5, wherein:

[0084] D1 is the core protection component of the transformer protection module, which achieves overvoltage protection for the signal amplification circuit by clamping the reverse electromotive force.

[0085] The parallel capacitors C4 and C5 can be connected in parallel across the primary winding of the transformer to form an LC resonant circuit with the primary inductance of TR1. The LC resonant circuit enables frequency selection and filtering, improves the signal purity after secondary amplification, and enhances the accuracy and reliability of cable detection.

[0086] Furthermore, optionally, the turns ratio design of TR1 can be adjusted according to the cable detection depth requirements (e.g., 1:2 boost, 1:3 deep detection) without changing the signal amplification circuit, thus enhancing system flexibility.

[0087] For the bidirectional design of D1, since the signal is an alternating signal (such as PWM / SPWM), the reverse electromotive force may be positive or negative. The bidirectional TVS can cover bidirectional spikes and improve the comprehensiveness of protection.

[0088] For the selection of materials for C4 and C5, ceramic capacitors (with good high-frequency characteristics) and electrolytic capacitors (with large capacitance) are usually connected in parallel to cover wide-band noise and optimize the filtering effect.

[0089] As can be seen, implementing this optional embodiment can absorb or discharge the reverse peak voltage generated by the transient of the transformer switch through the transformer protection module, preventing high voltage pulse feedback to the H-bridge switch transistor; it can suppress voltage spikes to avoid overvoltage breakdown of the motor drive chip, especially during load changes or short circuit faults, significantly reducing the risk of burnout; it can reduce the impact of transient interference on the first-stage amplifier circuit, ensuring that the output waveform is distortion-free and improving the resolvability of the detection signal; it can achieve secondary signal boosting through the transformer conversion circuit, breaking through the power bottleneck of single-stage amplification, thereby enhancing signal penetration and detection distance, and thus improving the accuracy and comprehensiveness of deep-buried cable positioning.

[0090] In an optional embodiment, such as Figure 4 As shown, Figure 4 This is a schematic diagram of the structure of an output protection circuit disclosed in an embodiment of the present utility model. The output protection circuit 20 includes a fuse 201 and a transient voltage suppressor 202.

[0091] Fuse 201 is electrically connected to signal amplifier circuit 10 to prevent signal amplifier circuit 10 from burning out.

[0092] Transient voltage suppressor 202 is electrically connected to signal amplifier circuit 10 and is used to absorb surge voltage;

[0093] like Figure 4 As shown, optional, Figure 4 In this context, F1 corresponds to fuse 201, and TVS1 corresponds to transient voltage suppressor 202. Further, optional features include... Figure 4 As shown, the output protection circuit may also include a filter capacitor C6;

[0094] For F1, when the output terminal is short-circuited or overloaded, the current increases abnormally, the fuse blows, and the circuit is cut off to prevent the signal amplification circuit from burning out due to overheating.

[0095] For TVS1, when an external surge (such as static electricity or lightning strike) or switching noise causes a sudden voltage increase, TVS1 turns on instantaneously, diverting excess energy to the ground wire and limiting the voltage peak.

[0096] Figure 4 J2 in the diagram represents the transmit port, used to transmit the final amplified alternating signal;

[0097] As can be seen, implementing this optional embodiment can provide dual protection against overcurrent and overvoltage through the synergistic effect of the fuse and TVS, thereby ensuring the reliability of the signal transmission circuit under extreme conditions and extending the service life of the equipment.

[0098] In an optional embodiment, through the above... Figures 2-4Connected sequentially, these components form a more complete schematic diagram of the signal transmission circuit used in cable detectors. The motor drive chip receives alternating signals, such as SPWM signals or complementary PWM signals, from the signal source through the control input terminals IN1 / IN2, controlling the on / off state of the internal H-bridge switches (such as MOSFETs): when IN1 is high and IN2 is low, the upper left / lower right switches of the H-bridge are turned on, and current flows from the +30V power supply through OUT1 and then returns to ground through OUT2; when IN1 is low and IN2 is high, the upper right / lower left switches of the H-bridge are turned on, and the current direction is reversed; and a first-stage amplified alternating signal is output from the OUT1 / OUT2 pins to drive the subsequent transformer conversion circuit; TR1 is a step-up transformer that amplifies the first-stage amplified alternating signal through electromagnetic induction, enhancing the signal's ability to penetrate soil / walls; the primary winding of TR1 and the parallel C4 / C5 capacitors form an LC resonant circuit, filtering out the signal... Frequency noise and environmental clutter are eliminated, preserving the target frequency signal and improving the signal-to-noise ratio. D1 is connected in parallel across the primary winding of TR1. When the H-bridge switch is turned off, the inductance of the primary winding of TR1 generates a reverse electromotive force, causing D1 to quickly conduct and clamp the voltage within a safe range, preventing damage to the switch of the motor drive chip. C6 is connected in series between the secondary winding of TR1 and F1 to block DC and pass AC (filtering the DC component in the signal and preserving the AC signal), preventing DC current from damaging the cable or receiver. F1 is connected in series in the circuit. When the cable under test is short-circuited, the current surges, F1 blows, cutting off the circuit and preventing damage to the transformer or signal amplification circuit. TVS1 is connected in parallel between the output of F1 and ground. When a surge voltage occurs in the circuit, TVS1 quickly conducts, clamping the voltage within a safe range and preventing damage to circuit components. The protected signal is connected to the conductor of the cable under test through the J2 interface. The signal injected into the cable generates an alternating electromagnetic field for the receiver to detect.

[0099] In conclusion, Figures 2-4 The complete circuit formed by connecting the components in sequence realizes the entire process of "signal generation → first-stage amplification → second-stage amplification → frequency selective filtering → output protection → signal transmission". The circuit enhances the signal penetration capability through multi-stage amplification, improves the signal purity through frequency selective filtering, ensures circuit safety through overcurrent / overvoltage protection, and finally injects the signal into the cable under test, providing the receiver with a clear and accurate detection signal.

[0100] Example 2

[0101] Please see Figure 5 , Figure 5 This is a structural schematic diagram of a cable detector disclosed in an embodiment of this utility model. Figure 5 The described cable detector, such as Figure 5As shown, the cable detector may include a transmitter 50, which includes a transmitter body 501, a signal source module 5011 disposed on the transmitter body 501, and a signal transmission circuit 5012 disposed in the transmitter body 501 as described in Embodiment 1 of this utility model. The signal source module 5011 and the signal transmission circuit 5012 are electrically connected.

[0102] In this embodiment of the present invention, optionally, the above-mentioned signal transmission circuit is integrated inside the transmitter body. For example, the signal transmission circuit is fixed on the PCB and installed inside the housing. Furthermore, the transmitter body also includes an input interface (such as a power switch and a signal adjustment knob) and an output interface (such as a probe or clip for connecting cables).

[0103] The signal transmitting circuit is connected to the output interface via a wire, and the amplified alternating signal is injected into the cable;

[0104] As the transmitting part of the cable detector, it generates and transmits detection signals (such as audio or radio frequency signals) to generate an electromagnetic field in underground or wall-mounted cables. The overall logic allows users to connect the transmitter to the target cable. After the signal transmission circuit is working, the receiver can detect the signal to locate the cable.

[0105] It is evident that implementing this utility model embodiment can endow the cable detector with strong signal, high reliability, and easy maintenance characteristics by incorporating a high-performance signal transmission circuit, thereby improving engineering construction efficiency and reducing operation and maintenance costs.

[0106] In this embodiment of the utility model, as an optional implementation method, such as... Figure 5 As shown, the signal source module 5011 includes an MCU module 50111. The MCU module 50111 is electrically connected to the signal transmitting circuit 5012 in Embodiment 1. Specifically, the MCU module 50111 is electrically connected to the signal amplification circuit 10 and is used to provide an alternating signal to the signal amplification circuit 10.

[0107] In this embodiment of the present invention, the signal source module 5011 may further include analog / mixed signal chips such as SG3525, UC3842, and TL494, which are specifically designed to generate PWM signals. The specific application scenario is relevant to the actual application scenario, and this embodiment of the present invention does not impose any specific limitations on this.

[0108] In this embodiment of the invention, the MCU module 50111 (microcontroller unit), such as STM32, Arduino, or Raspberry Pi, is mounted on the PCB of the transmitter body. Its output pins (GPIO) are directly connected to the input pins of the signal amplification circuit (such as IN1 and IN2 of the motor driver chip) via wires. The internal program of the MCU module 50111 generates alternating signals (such as the aforementioned SPWM or PWM).

[0109] Operating logic: The MCU module 50111 generates signal parameters (frequency, duty cycle) based on user settings (such as via buttons or software configuration);

[0110] Function: Provides a programmable signal source, allowing for flexible adjustment of signal characteristics to adapt to different detection environments (such as different cable materials or depths). In implementation, the MCU module 50111 can also monitor circuit status (e.g., via an ADC).

[0111] As can be seen, implementing this optional embodiment can achieve flexible configuration and intelligent control of signal parameters through the MCU module 50111, thereby improving the adaptability and energy efficiency of the cable detector and meeting diverse field operation needs.

[0112] In this optional embodiment, as an optional implementation method, such as Figure 6 As shown, Figure 6 This is a schematic diagram of a voltage detection circuit disclosed in an embodiment of the present utility model. The transmitter 50 also includes a voltage detection circuit 5013 disposed in the transmitter body 501. The voltage detection circuit 5013 is electrically connected to the signal source module 5011 and the cable to be tested, respectively, for detecting the voltage in the cable to be tested.

[0113] like Figure 6 As shown, optionally, the voltage detection circuit 5013 may include a set of voltage divider resistors R2-R7 and a filter capacitor C7; the present invention does not specifically limit the number of the above-mentioned voltage divider resistor set and filter capacitor.

[0114] Figure 6 In the signal source module 5011, the voltage detection circuit 5013 is electrically connected to the NCV pin of the MCU module and is electrically connected to the cable under test through the transmit port J2 to detect the voltage in the cable under test.

[0115] As can be seen, implementing this optional embodiment can feed back the detected voltage in the cable under test to the MCU, and perform a voltage divider conversion operation on the detected voltage signal of the transmitter port based on the voltage divider resistor set, so as to ensure that the detected voltage signal falls within the input range adapted by the MCU module, thereby improving the detection reliability and safety.

[0116] In this optional embodiment, as another alternative implementation, such as Figure 5 As shown, the cable detector described above may also include a receiver 60, which is used to receive signals emitted by the transmitter 50 for cable detection.

[0117] In this optional embodiment, the receiver can analyze the transmitted signal through electromagnetic induction and combine it with a positioning algorithm (such as field strength gradient analysis) to accurately identify the cable location, depth, and path. Furthermore, the receiver can also provide real-time feedback on the detection results through audio-visual prompts (buzzer / LCD screen) to simplify the operation process and improve the user experience.

[0118] As can be seen, implementing this optional embodiment can form an end-to-end detection solution through the collaborative work of the receiver and transmitter, enabling functions such as breakpoint detection and multi-cable differentiation, expanding the application boundaries of the device, and thus comprehensively improving the accuracy and completeness of cable positioning.

[0119] The foregoing has provided a detailed description of a signal transmitting circuit, transmitter, and cable detector disclosed in the embodiments of this utility model. Specific embodiments have been used to illustrate the principles and implementation methods of this utility model. However, the above preferred embodiments are not intended to limit this utility model. The descriptions of the above embodiments are merely for the purpose of helping to understand the method and core ideas of this utility model. Furthermore, for those skilled in the art, based on the ideas of this utility model, changes may be made in the specific implementation methods and application scope without departing from the spirit and scope of this utility model. Therefore, the protection scope of this utility model is determined by the scope defined in the claims.

Claims

1. A signal transmitting circuit applied to a cable detector, characterized in that, The signal transmitting circuit includes a signal amplification circuit and an output protection circuit; The signal amplification circuit includes a motor driver chip, which has an H-bridge circuit. The motor driver chip is electrically connected to a signal source and is used to amplify the alternating signal provided by the signal source through the H-bridge circuit. The output protection circuit is electrically connected to the signal amplification circuit and is used to transmit the alternating signal output by the signal amplification circuit, while preventing the signal amplification circuit from burning out.

2. The signal transmitting circuit for cable detector according to claim 1, wherein, The alternating signal provided by the signal source is an SPWM signal or a PWM signal.

3. The signal transmitting circuit for cable detector according to claim 1, wherein, The signal amplification circuit also includes a drive filtering module, which is electrically connected to the motor drive chip and is used to provide filtered power to the motor drive chip.

4. The signal transmitting circuit for cable detector according to claim 1, wherein The signal transmitting circuit further includes a voltage converter circuit, the two ends of which are electrically connected to the signal amplification circuit and the output protection circuit, respectively. The voltage converter circuit is used to perform secondary amplification on the alternating signal after primary amplification and output it to the output protection circuit.

5. The signal transmitting circuit for cable detector according to claim 4, wherein, The transformer conversion circuit includes a transformer and a transformer protection module; The transformer is electrically connected to the output protection circuit, and the transformer is used to perform two-stage amplification processing on the alternating signal; The two ends of the transformer protection module are electrically connected to the signal amplification circuit and the transformer, respectively, to prevent the reverse electromotive force generated by the transformer from damaging the signal amplification circuit.

6. The signal transmitting circuit for cable detector according to claim 1, wherein The output protection circuit includes a fuse and a transient voltage suppressor; The fuse is electrically connected to the signal amplification circuit to prevent the signal amplification circuit from burning out. The transient voltage suppressor is electrically connected to the signal amplification circuit and is used to absorb surge voltage.

7. A transmitter for a cable locator, characterized by The transmitter includes a transmitter body, a signal source module disposed on the transmitter body, and a signal transmission circuit disposed in the transmitter body as described in any one of claims 1-6. The signal source module is electrically connected to the signal transmission circuit and is used to provide an alternating signal to the signal transmission circuit.

8. The cable locator transmitter of claim 7, wherein, The signal source module includes an MCU module.

9. The cable locator transmitter of claim 7, wherein, The transmitter also includes a voltage detection circuit disposed in the transmitter body. The voltage detection circuit is electrically connected to the signal source module and the cable to be tested, respectively, and is used to detect the voltage in the cable to be tested.

10. A cable probe, characterized by, It includes a receiver and a transmitter as described in any one of claims 7-9, wherein the receiver is used to receive signals emitted by the transmitter for cable detection.

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