Network ignition monitoring circuit

Abstract

The utility model discloses a network ignition monitoring circuit, which comprises a first detection module, a second detection module, a comparison circuit and a fault capture circuit, the first detection module is used for detecting a reference ambient light signal, and the second detection module is used for detecting a preset position ambient light signal; the comparison circuit is respectively connected with the first detection module and the second detection module and is used for comparing the reference ambient light signal with the preset position ambient light signal and outputting a comparison result signal; and the fault capturing circuit is connected with the comparison circuit and is used for generating a fault capturing signal according to the comparison result signal. According to the technical scheme provided by the utility model, the double detection modules are arranged to respectively detect the preset position environment light signal and the reference environment light signal, so that the false alarm condition is effectively avoided, the monitoring accuracy is improved, the sparking phenomenon can be timely monitored, and the specific sparking position can be accurately determined.

Description

TECHNICAL FIELD

[0001] The utility model relates to high frequency network monitoring technical field especially relates to a network spark monitor circuit. BACKGROUND

[0002] With the increasing progress of life and technology, high frequency network is more and more applied to various industries, but also needs to monitor high frequency network in time, so as to find fault in time.

[0003] At present, in actual work, there are the following problems: the antenna deployment room under the antenna is unattended when working, and is far away from the machine room control room, and various working frequency antennas are sporadically distributed around the machine room. Once the working antenna fails, such as antenna disconnection or antenna winding by foreign matter (kite, etc.), it may cause a certain component in the normal high frequency network to have continuous sparking or be broken down by high frequency voltage, and the attendant in the duty room cannot immediately know the situation at this time, and often can only check the fault reason step by step through the abnormal alarm information of the transmitter. But this method cannot find the fault in time, and it is time-consuming and laborious to troubleshoot, and when the fault is found, it has caused great damage.

[0004] The existing network spark monitoring circuit cannot find the fault in time and is not intelligent enough, which becomes a technical problem to be solved in the industry. UTILITY MODEL CONTENTS

[0005] The utility model provides a network spark monitoring circuit to solve the problem that the existing network spark monitoring circuit cannot find the fault in time and is not intelligent enough.

[0006] According to one aspect of the utility model, a network spark monitoring circuit is provided, comprising: a first detection module, a second detection module, a comparison circuit and a fault capture circuit;

[0007] The first detection module is used for detecting a reference ambient light signal, and the second detection module is used for detecting a preset position ambient light signal.

[0008] The comparison circuit is connected with the first detection module and the second detection module respectively, and is used for comparing the reference ambient light signal and the preset position ambient light signal and outputting a comparison result signal.

[0009] The fault capture circuit is connected with the comparison circuit, and is used for generating a fault capture signal according to the comparison result signal.

[0010] Optionally, the first detection module comprises a first photosensitive sensor and a first resistor; the first photosensitive sensor is connected with the first end of the first resistor, and the second end of the first resistor is connected with the first input end of the comparison circuit.

[0011] The second detection module comprises a second photosensitive sensor and a second resistor; the second photosensitive sensor is connected with the first end of the second resistor, and the second end of the second resistor is connected with the second input end of the comparison circuit.

[0012] Optionally, the comparison circuit comprises an operational amplifier and a third resistor.

[0013] The inverting input end of the operational amplifier is connected with the second end of the first resistor, and the non-inverting input end of the operational amplifier is connected with the second end of the second resistor.

[0014] The first end of the third resistor is connected with the inverting input end of the operational amplifier, and the second end of the third resistor is connected with the output end of the operational amplifier.

[0015] Optionally, the comparison circuit further comprises a fourth resistor.

[0016] The first end of the fourth resistor is connected with the non-inverting input end of the operational amplifier, and the second end of the fourth resistor is grounded.

[0017] Optionally, the fault capture circuit comprises a peak detection unit, a switching unit and a micro-processing unit.

[0018] The peak detection unit is configured to detect and hold the comparison result signal, the first end of the peak detection unit is connected with the comparison circuit, the second end of the peak detection unit is connected with the control end of the switching unit, and the third end of the peak detection unit is grounded.

[0019] The first end of the switching unit is connected with a power supply, the second end of the switching unit is connected with the micro-processing unit, and the third end of the switching unit is grounded.

[0020] Optionally, the peak detection unit comprises a diode and a first capacitor.

[0021] The anode of the diode is connected with the comparison circuit, the cathode of the diode is connected with the first end of the first capacitor, and the second end of the first capacitor is grounded.

[0022] Optionally, the switching unit comprises a first switch and a second capacitor.

[0023] The control end of the first switch is connected with the cathode of the diode, the first end of the first switch is connected with a power supply, and the second end of the first switch is connected with the first end of the second capacitor.

[0024] The second end of the second capacitor is grounded.

[0025] Optionally, the switch unit further comprises a fifth resistor.

[0026] The first end of the fifth resistor is connected with the second end of the first switch, and the second end of the fifth resistor is grounded.

[0027] Optionally, the first switch comprises a triode or a MOS tube.

[0028] Optionally, the switch unit is connected with the micro-processing unit through an OR gate.

[0029] The technical scheme of the embodiment of the utility model, through the first detection module obtains the reference ambient light signal of the matching network in the environment, through the second detection module detects the matching network preset position ambient light signal. Through the comparison circuit compares the reference ambient light signal and the preset position light signal and outputs the comparison result signal to the fault capture circuit, the fault capture circuit analyzes and processes the comparison result signal, and outputs the fault capture signal. By setting 2 detection modules, one is used for detecting the reference ambient light signal, and one is used for detecting the preset position ambient light signal, by comparing the preset position ambient light signal with the reference ambient light signal, effectively avoid the false alarm situation, improve the accuracy of monitoring, and also can monitor the present striking phenomenon in time, accurately determine the specific striking position in the matching network, so as to take corresponding measures in time, avoid exaggeration damage, effectively reduce the property damage.

[0030] It should be understood that the contents described in this part are not intended to identify the key or important features of the embodiments of the utility model, and are not used to limit the scope of the utility model. Other features of the utility model will become easy to understand through the following description. BRIEF DESCRIPTION OF DRAWINGS

[0031] In order to more clearly illustrate the technical scheme in the embodiment of the utility model, the drawings needed in the embodiment description will be briefly introduced below, and obviously, the drawings in the following description are only some embodiments of the utility model, and for those skilled in the art, other drawings can be obtained according to these drawings without creating labor.

[0032] Figure 1 A structure schematic view of a high-frequency network provided by the embodiment of the utility model is shown in the figure.

[0033] Figure 2 A structure schematic view of a network striking monitoring circuit provided by the embodiment of the utility model is shown in the figure.

[0034] Figure 3 Another structure schematic view of a network striking monitoring circuit provided by the embodiment of the utility model is shown in the figure.

[0035] Figure 4 Another network fire monitoring circuit structure schematic diagram provided by the embodiment of the utility model,

[0036] Figure 5 Another network fire monitoring circuit structure schematic diagram provided by the embodiment of the utility model,

[0037] Figure 6 Another network fire monitoring circuit structure schematic diagram provided by the embodiment of the utility model. DETAILED DESCRIPTION

[0038] In order to make the person skilled in the art better understand the utility model scheme, the technical scheme in the embodiment of the utility model will be described clearly and completely below in conjunction with the drawings in the embodiment of the utility model. Obviously, the described embodiment is only a part of the embodiment of the utility model, not all. Based on the embodiment in the utility model, all other embodiments obtained by the person skilled in the art without creative labor should belong to the protection scope of the utility model.

[0039] It should be noted that the terms "first", "second" and the like in the specification and claims of the utility model and the above-mentioned drawings are used to distinguish similar objects, and do not have to be used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so that the embodiments of the utility model described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "include" and "have" and any modification thereof are intended to cover non-exclusive inclusion, for example, the process, method, system, product or equipment including a series of steps or units does not have to be limited to the clearly listed steps or units, but can include other steps or units not clearly listed or inherent to these processes, methods, products or equipment.

[0040] Figure 1 The structure schematic diagram of a high-frequency network provided by the embodiment of the utility model, Figure 2 The structure schematic diagram of a network fire monitoring circuit provided by the embodiment of the utility model. Referring to Figure 1 And Figure 2 The network fire monitoring circuit 100 comprises a first detection module 10, a second detection module 20, a comparison circuit 30 and a fault capture circuit 40. The first detection module 10 is used for detecting a reference ambient light signal, and the second detection module 20 is used for detecting a preset position ambient light signal. The comparison circuit 30 is connected with the first detection module 10 and the second detection module 20 respectively, and is used for comparing the reference ambient light signal and the preset position ambient light signal and outputting a comparison result signal. The fault capture circuit 40 is connected with the comparison circuit 30, and is used for generating a fault capture signal according to the comparison result signal.

[0041] Specifically, referring to Figure 1 , the high-frequency network generally includes a medium wave antenna, a medium wave transmitting pole and an antenna matching network, the antenna matching network generally consists of a lightning protection circuit, a radio frequency suppression circuit and a matching network, the lightning protection circuit is mainly used for preventing the influence of thunder and lightning on the transmitter in the thunderstorm season, the radio frequency suppression circuit is mainly used for reducing the negative influence of other working frequencies on the working frequency, and the matching network is mainly used for converting the impedance of the antenna into the impedance required for the working of the medium wave transmitter, and a second-order Butterworth filter is generally used for design. Generally, the inductor coil which affects the impedance change in the matching network will appear the sparking phenomenon, and if the sparking time is long, other circuits will be seriously damaged.

[0042] Specifically, referring to Figure 2 The network sparking monitoring circuit provided by the embodiment of the utility model mainly detects the matching network, the first detection module 10 is mainly used for detecting the reference ambient light signal of the environment where the matching network is located, the matching network is generally located in a closed environment, and the first detection module 10 can be located at any position in the closed environment which is not affected by sparking. The second detection module 20 is located near the antenna of the matching network where the sparking is prone to occur, and is used for detecting the ambient light signal of the preset position, and the preset position can be the position of the matching network where the sparking phenomenon is prone to occur. After the first detection module 10 detects the reference ambient signal and the second detection module 20 detects the ambient light signal of the preset position, the reference light signal and the ambient light signal of the preset position are sent to the comparison circuit 30. The comparison circuit 30 is connected with the first detection module 10 and the second detection module 20 respectively, and after receiving the reference ambient light signal and the ambient light signal of the preset position, the comparison circuit compares the reference ambient light signal and the ambient light signal of the preset position, and outputs the comparison result signal to the fault capture circuit 40. When the sparking phenomenon occurs at the preset position, the ambient light signal of the preset position and the reference ambient light signal are different, and the comparison circuit 30 generates a comparison result signal at this time. The fault capture circuit 40 is connected with the comparison circuit 30, and after receiving the comparison result signal, the fault capture circuit generates the fault capture signal according to the comparison result signal. After receiving the comparison result signal, the fault capture circuit 40 processes the comparison result signal, and outputs the high-level fault capture signal for further analysis and processing of the rear end.

[0043] The technical scheme provided by the embodiment of the utility model discloses, through the first detection module, the reference ambient light signal of the environment where the matching network is at is acquired, and through the second detection module, the ambient light signal of the preset position of the matching network is detected, through the comparison circuit, the reference ambient light signal and the preset position light signal are compared and the comparison result signal is output to the fault capture circuit, the comparison result signal is analyzed and handled by the fault capture circuit, and the fault capture signal is output, through setting 2 detection modules, one is used for detecting the reference ambient light signal, and one is used for detecting the preset position ambient light signal, through comparing the preset position ambient light signal with the reference ambient light signal, the situation of false alarm is effectively avoided, the accuracy of monitoring is improved, and the phenomenon of striking a match is also monitored in time, the specific striking position in the matching network is accurately determined, so that corresponding measures are taken in time, exaggeration damage is avoided, and property damage is effectively reduced.

[0044] Optionally, Figure 3 The structure schematic diagram of another network striking a match monitoring circuit provided by the embodiment of the utility model is provided. Figure 3 The first detection module 10 includes the first photosensitive sensor 11 and the first resistor R1, the first photosensitive sensor 11 is connected with the first end of the first resistor R1, and the second end of the first resistor R1 is connected with the first input end of the comparison circuit 30.

[0045] Specifically, the first detection module 10 is mainly used for detecting the reference ambient light signal, the first detection module 10 includes the first photosensitive sensor 11 and the first resistor R1, the first photosensitive sensor 11 is connected with the first end of the first resistor R1, and the second end of the first resistor R1 is connected with the first input end of the comparison circuit 30. The first photosensitive sensor 11 is used for detecting the reference ambient light signal of the space where the matching network is at, and the first resistor R1 mainly plays a current limiting role. The second detection module 20 includes the second photosensitive sensor 21 and the second resistor R2, the second photosensitive sensor 21 is connected with the first end of the second resistor R2, and the second end of the second resistor R2 is connected with the second input end of the comparison circuit 30. The second photosensitive sensor 21 is used for detecting the ambient light signal of the preset position of the matching network, and the second resistor R2 mainly plays a current limiting role. Among them, the first photosensitive sensor 11 and the second photosensitive sensor 21 can be PT550 photosensitive sensors, the corresponding time of the model photosensitive sensor is short, the corresponding speed is fast, the dynamic monitoring range is large, the output current is highly proportional to the illumination intensity, the change of the ambient light can be accurately reflected, the low light environment has good response, even in the weak light condition, the change of the light intensity can be accurately detected, and the accuracy of monitoring is improved.

[0046] Optionally, Figure 4 Another network fire monitoring circuit structure schematic diagram provided by the embodiment of the utility model is shown in the figure. Based on the above embodiment, referring to Figure 4 The comparison circuit 30 comprises an operational amplifier 31 and a third resistor R3, the inverting input end of the operational amplifier 31 is connected with the second end of the first resistor R1, the non-inverting input end of the operational amplifier 31 is connected with the second end of the second resistor R2; the first end of the third resistor R3 is connected with the inverting input end of the operational amplifier 31, and the second end of the third resistor R3 is connected with the output end of the operational amplifier 31.

[0047] Specifically, the comparison circuit 30 mainly compares the reference ambient light signal and the preset position ambient light signal sent by the first detection module 10 and the second detection module 20, and outputs a comparison result signal. The comparison circuit 30 comprises an operational amplifier 31 and a third resistor R3, the inverting input end of the operational amplifier 31 is connected with the second end of the first resistor R1, the non-inverting input end of the operational amplifier 31 is connected with the second end of the second resistor R2; the first end of the third resistor R3 is connected with the inverting input end of the operational amplifier 31, and the second end of the third resistor R3 is connected with the output end of the operational amplifier 31. After the operational amplifier 31 receives the reference ambient light signal sent by the first detection module 10 and the preset position ambient light signal sent by the second detection module 20, the received signals are amplified and compared, the two input signals are calculated according to the superposition theorem, and the output comparison result signal is determined. The third resistor R3 is a feedback resistor, so that the operational amplifier 31 works in the linear region. For example, when the fire phenomenon does not occur, the comparison result signal = preset position ambient light signal - reference ambient light signal ≈ 0, and when the continuous fire phenomenon occurs, the comparison result signal gradually increases and is transmitted to the fault capture circuit 30 for further analysis and processing.

[0048] Optionally, based on the above embodiment, referring to Figure 4 The comparison circuit 30 further comprises a fourth resistor R4; the first end of the fourth resistor R4 is connected with the non-inverting input end of the operational amplifier 31, and the second end of the fourth resistor R4 is grounded.

[0049] Specifically, the comparison circuit 30 further comprises a fourth resistor R4, the first end of the fourth resistor R4 is connected with the non-inverting input end of the operational amplifier 31, and the second end of the fourth resistor R4 is grounded. The fourth resistor R4 can effectively improve the stability and reliability of the circuit, ensure that the operational amplifier 31 works in the linear range, avoid performance degradation or abnormal oscillation caused by unstable working point, and also effectively reduce current noise, reduce input signal reflection and distortion, improve the precision of the circuit, and further improve the accuracy of the detection result.

[0050] Optionally, Figure 5Another network fire monitoring circuit structure schematic diagram provided by the embodiment of the utility model is shown in the figure. Figure 5 The fault capture circuit 40 comprises a peak detection unit 41, a switch unit 42 and a micro-processing unit 43; the peak detection unit 41 is used for detecting and retaining a comparison result signal, the first end of the peak detection unit 41 is connected with the comparison circuit 30, the second end of the peak detection unit 41 is connected with the control end of the switch unit 42, and the third end of the peak detection unit 41 is grounded; the first end of the switch unit 42 is connected with a power supply, the second end of the switch unit 42 is connected with the micro-processing unit 43, and the third end of the switch unit 42 is grounded.

[0051] Specifically, the fault capture circuit 40 comprises the peak detection unit 41, the switch unit 42 and the micro-processing unit 43, the peak detection unit 41 is mainly used for detecting and retaining the peak value of the comparison result signal output by the comparison circuit 30, the first end of the peak detection unit 41 is connected with the comparison circuit 30, and the second end is connected with the control end of the switch unit 42; when the peak detection unit 41 receives the comparison result signal, the peak value of the comparison result signal is extracted, the switch unit 42 is turned on when the peak value is large, the switch unit 42 is connected with the micro-processing unit 43, after the switch unit 42 is turned on, the micro-processing unit 43 receives the comparison result signal, and the micro-processing unit 43 generates a fault capture signal according to the comparison result signal.

[0052] Optionally, Figure 6 Another network fire monitoring circuit structure schematic diagram provided by the embodiment of the utility model is shown in the figure. Figure 6 The peak detection unit 41 comprises a diode D1 and a first capacitor C1; the positive pole of the diode D1 is connected with the comparison circuit 30, the negative pole of the diode D1 is connected with the first end of the first capacitor C1, and the second end of the first capacitor C1 is grounded.

[0053] Specifically, the peak detection unit 41 includes a diode D1 and a first capacitor C1. The positive electrode of the diode D1 is connected with the comparison circuit 30, the negative electrode of the diode D1 is connected with the first end of the first capacitor C1, and the second end of the first capacitor C1 is grounded. The peak detection unit 41 mainly realizes its function based on the charge-discharge characteristics of the capacitor and the unidirectional conduction of the diode. When the comparison result signal output by the comparison circuit 30 is in the positive half cycle and the amplitude is greater than the voltage across the capacitor, the diode D1 is turned on, which is equivalent to a short circuit state. At this time, the comparison result signal charges the first capacitor C1 through the diode D1. Since the voltage across the first capacitor C1 cannot change abruptly, the voltage across the first capacitor C1 gradually rises to the peak of the comparison result signal. When the amplitude of the comparison result signal starts to decrease and is lower than the voltage across the first capacitor C1, the diode D1 is reverse-biased and cut off. At this time, because the first capacitor C1 has the characteristics of storing charge and maintaining voltage, the output voltage remains at the peak of the first capacitor C1 during the cut-off period of the diode D1, i.e. close to the peak of the comparison result signal.

[0054] Optionally, on the basis of the above embodiment, continuing to refer to Figure 6 The switch unit 42 includes a first switch 421 and a second capacitor C2. The control end of the first switch 421 is connected with the negative electrode of the diode D1, the first end of the first switch 421 is connected with the power supply, and the second end of the first switch 421 is connected with the first end of the second capacitor C2. The second end of the second capacitor C2 is grounded.

[0055] Specifically, the switch unit 42 includes a first switch 421 and a second capacitor C2. The control end of the first switch 421 is connected with the negative electrode of the diode D1 in the peak detection unit 41, the first end of the first switch 421 is connected with the power supply, the second end of the first switch 421 is connected with the first end of the second capacitor C2, and the second end of the second capacitor C2 is grounded. When the peak of the comparison result signal output by the peak detection unit 41, the first switch 421 is turned on, so that the comparison result signal is transmitted to the micro-processing unit 43, and the micro-processing unit 43 further analyzes and processes it to generate a fault capture signal. The first switch 421 can be a triode or a MOS tube.

[0056] Optionally, on the basis of the above embodiment, continuing to refer to Figure 6 The switch unit 42 further includes a fifth resistor R5. The first end of the fifth resistor R5 is connected with the second end of the first switch 421, and the second end of the fifth resistor R5 is grounded.

[0057] Specifically, the switch unit 42 further comprises a fifth resistor R5, a first end of the fifth resistor R5 is connected with the second end of the first switch 421, and a second end of the fifth resistor R5 is grounded. The fifth resistor R5 cooperates with the second capacitor C2 to effectively protect the circuit by discharging the charge stored in the second capacitor C2 during discharging of the second capacitor C2.

[0058] Optionally, on the basis of the above embodiment, continuing to refer to Figure 6 The switch unit 42 is connected with the micro-processing unit 43 through an OR gate.

[0059] Specifically, the second end of the switch unit 42 is connected with the input end of the micro-processing unit 43 to transmit the processed comparison result signal to the micro-processing unit 43, and the micro-processing unit 43 mainly processes the received comparison result signal to generate a fault capture signal. The micro-processing unit can adopt a CD4072 dual OR gate 4-input integrated circuit chip, which mainly comprises two independent 4-input OR gate units, each unit has 4 input ends and 1 output end, and can independently perform OR operation. When any one input end is at a high level, the corresponding output end outputs a high level signal. The second end of the switch unit 42 is connected to one of the input pins of the chip, and when the input pin receives a high level comparison result signal, the corresponding output pin outputs a high level fault capture signal. When the micro-processing unit 43 is used, the processing chip has 8 input pins and can simultaneously receive 8 comparison result signals, so that 8 groups of preset positions of the matching network can be detected at the same time. Moreover, when the matching network to be detected is in the same environment, the same first detection module 10 can be shared to obtain the reference ambient light signal. Through flexible combination, the user's requirements for adding or deleting monitoring points can be met, the monitoring of all suspicious points of the matching network can be completely realized, the circuit design is simple, and the integration is high.

[0060] The above specific embodiments do not constitute a limitation on the protection scope of the present application. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A network spark monitoring circuit, characterized by, The application relates to a fault capture circuit and a method for capturing fault. The application comprises a first detection module, a second detection module, a comparison circuit and a fault capture circuit. The first detection module is used for detecting a reference ambient light signal, and the second detection module is used for detecting a preset position ambient light signal. The comparison circuit is connected with the first detection module and the second detection module respectively, and is used for comparing the reference ambient light signal and the preset position ambient light signal and outputting a comparison result signal. The fault capture circuit is connected with the comparison circuit, and is used for generating a fault capture signal according to the comparison result signal.

2. The network spark monitoring circuit of claim 1, wherein, The first detection module comprises a first photosensitive sensor and a first resistor. The first photosensitive sensor is connected with the first end of the first resistor.

3. The network spark monitoring circuit of claim 2, wherein, The second detection module comprises a second photosensitive sensor and a second resistor. The second photosensitive sensor is connected with the first end of the second resistor. The comparison circuit comprises an operational amplifier and a third resistor.

4. The network spark monitoring circuit of claim 3, wherein, The inverting input end of the operational amplifier is connected with the second end of the first resistor. The non-inverting input end of the operational amplifier is connected with the second end of the second resistor.

5. The network spark monitoring circuit of claim 1, wherein, The first end of the third resistor is connected with the inverting input end of the operational amplifier. The second end of the third resistor is connected with the output end of the operational amplifier. The comparison circuit further comprises a fourth resistor.

6. The network spark monitoring circuit of claim 5, wherein, The first end of the fourth resistor is connected with the non-inverting input end of the operational amplifier. The second end of the fourth resistor is grounded.

7. The network spark monitoring circuit of claim 6, wherein, The fault capture circuit comprises a peak value detection unit, a switch unit and a micro processing unit. The peak value detection unit is used for detecting and maintaining the comparison result signal. The first end of the peak value detection unit is connected with the comparison circuit.

8. The network spark monitoring circuit of claim 7, wherein, The second end of the peak value detection unit is connected with the control end of the switch unit. The third end of the peak value detection unit is grounded.

9. The network spark monitoring circuit of claim 7, wherein, The peak value detection unit comprises a diode and a first capacitor.

10. The network spark monitoring circuit of claim 5, wherein, The positive electrode of the diode is connected with the comparison circuit. The negative electrode of the diode is connected with the first end of the first capacitor. The second end of the first capacitor is grounded. The switch unit comprises a first switch and a second capacitor. The control end of the first switch is connected with the negative electrode of the diode. The first end of the first switch is connected with a power supply. The second end of the first switch is connected with the first end of the second capacitor. The second end of the second capacitor is grounded. The switch unit further comprises a fifth resistor. The first end of the fifth resistor is connected with the second end of the first switch. The second end of the fifth resistor is grounded. The first switch comprises a triode or a MOS tube. The switch unit is connected with the micro processing unit through an OR gate.

Images