Power supply undervoltage alarm monitoring circuit

Abstract

The utility model relates to the field of undervoltage detection circuits, in particular to a power supply undervoltage alarm monitoring circuit, which comprises a voltage-stabilized power supply, a voltage division circuit, a voltage-stabilized reference circuit, an operational amplifier (U1), a trigger switch circuit, an alarm circuit and a load, the output end of the voltage-stabilized power supply further outputs voltage-stabilized reference voltage to the same-direction end of the operational amplifier (U1) through the voltage-stabilized reference circuit, the output end of the operational amplifier (U1) is electrically connected with the alarm circuit through the trigger switch circuit, and the voltage-stabilized power supply further communicates with a load through the trigger switch circuit; wherein the operational amplifier (U1) compares the divided voltage with the voltage-stabilizing reference voltage and outputs a corresponding signal to the trigger switch circuit according to a comparison result, and the trigger switch circuit further selects to start the alarm circuit and disconnect the voltage-stabilizing power supply and the load at the same time.

Description

TECHNICAL FIELD

[0001] The utility model relates to the field of under-voltage detection circuit, especially a power under-voltage alarm monitoring circuit. BACKGROUND

[0002] In the current power management field, real-time monitoring and protection of power voltage are the key links to ensure the normal operation of electronic equipment. However, the existing power detection circuit is generally complex in design, which not only requires precise circuit layout, but also needs to be controlled and data processed with complex software programs. This soft and hard combined detection method not only increases the complexity of the system, but also makes the design, debugging and maintenance process of the entire circuit cumbersome and time-consuming.

[0003] Specifically, the traditional power detection circuit often contains multiple microprocessors or controllers, which not only need to undertake the tasks of data collection, processing and decision-making, but also need to interact with external circuits. In order to realize accurate voltage monitoring and alarm function, these software programs need to be strictly written, tested and debugged, which undoubtedly increases the cost and development cycle of the circuit.

[0004] In addition, the detection method of software and hardware combination also faces the problems of high cost and difficulty in popularization. On the one hand, high-performance microprocessors and controllers are not cheap; on the other hand, the cost of software development, subsequent maintenance and upgrading is also an important part that cannot be ignored.

[0005] Therefore, it is particularly important to develop a power under-voltage alarm monitoring circuit with simple design, low cost and easy popularization. SUMMARY

[0006] To solve the above problems, the utility model provides a kind of power under-voltage alarm monitoring circuit, by simplifying circuit structure and reducing the dependence on software, realize the real-time monitoring and protection of power voltage, to meet the demand of the majority of users to power stability and reliability.

[0007] In order to achieve the above object, the utility model adopts the technical scheme: a power supply under -voltage alarm monitoring circuit, its characterized in be: including stabilized power supply, voltage dividing circuit, voltage reference circuit, operational amplifier U1, trigger switch circuit, alarm circuit, load, the output of stabilized power supply passes through voltage dividing circuit and exports the voltage division voltage to the reverse end of operational amplifier U1, the output of stabilized power supply still exports voltage reference voltage to the same direction end of operational amplifier U1 through voltage reference circuit, wherein the output of operational amplifier U1 is electrically connected with alarm circuit through trigger switch circuit, and stabilized power supply still communicates with load through trigger switch circuit, wherein operational amplifier U1 exports corresponding signal to trigger switch circuit according to the comparison result by comparing voltage division voltage and voltage reference voltage, and trigger switch circuit further selects to start alarm circuit and disconnects the connection between stabilized power supply and load.

[0008] Further, the voltage dividing circuit includes a fourth resistor R4 and a fifth resistor R5, wherein one end of the fourth resistor R4 is connected with the positive electrode of the stabilized power supply, the other end of the fourth resistor R4 is connected with one end of the fifth resistor R5, and the other end of the fifth resistor R5 is grounded.

[0009] Further, the voltage reference circuit includes a voltage stabilizing diode D1, a current limiting resistor R3 and a first resistor R1, wherein one end of the current limiting resistor R3 is connected with the positive electrode of the stabilized power supply, the other end of the current limiting resistor R3 is connected with the negative electrode of the voltage stabilizing diode D1, the positive electrode of the voltage stabilizing diode D1 is grounded, and the negative electrode of the voltage stabilizing diode D1 is connected with the same direction end of the operational amplifier U1 through the first resistor R1.

[0010] Further, the voltage dividing circuit further includes a second resistor R2, one end of the second resistor R2 is connected with the node between the fourth resistor R4 and the fifth resistor R5, and the other end of the second resistor R2 is connected with the reverse end of the operational amplifier U1.

[0011] Further, the trigger switch circuit includes a relay, a sixth resistor R6 and a first triode Q1, wherein the output of the operational amplifier U1 is connected with the base of the first triode Q1 through the sixth resistor R6, the emitter of the first triode Q1 is grounded, and the collector of the first triode Q1 is connected with the VCC power supply through the relay, wherein the alarm circuit is also connected with the VCC power supply through the relay to realize power supply, and the relay makes the alarm circuit start or stop according to whether the first triode Q1 is in cut-off state or conducting state.

[0012] Further, the trigger switch circuit further includes a second diode D2, the collector of the first triode Q1 is connected with the positive electrode of the second diode D2, and the negative electrode of the second diode D2 is connected with the VCC power supply through the relay.

[0013] Further, the alarm circuit comprises a buzzer B1, a fault prompt lamp LED1 and an eighth resistor R8, wherein one end of the eighth resistor R8 is connected with the VCC power supply through a relay, and the other end of the eighth resistor R8 is connected with the fault prompt lamp LED1, and the buzzer B1 is also connected with the VCC power supply through the relay.

[0014] Further, the normal working prompt circuit comprises a normal working prompt lamp LED2 and a seventh resistor R7, wherein one end of the seventh resistor R7 is connected with the VCC power supply through a relay, and the other end of the seventh resistor R7 is connected with the normal working prompt lamp LED2, and the relay is controlled to be in the conducting state or the cut-off state according to the first triode Q1, so as to control the starting or the closing of the normal working prompt circuit.

[0015] Further, the relay comprises a No. 1 end, a No. 2 end, a first contact switch K1-1, a second contact switch K1-2 and a third contact switch K1-3, wherein the collector of the first triode Q1 is connected with the No. 1 end, the No. 2 end is connected with the VCC power supply, the voltage stabilizing power supply is connected with the load through the first contact switch K1-1, the negative electrode of the second diode D2 is connected with the buzzer B1 and the eighth resistor R8 through the second contact switch K1-2, and the negative electrode of the second diode D2 is connected with the seventh resistor R7 through the third contact switch K1-3.

[0016] Further, the first contact switch K1-1 and the third contact switch K1-3 are normally closed, and the second contact switch K1-2 is normally open.

[0017] The utility model discloses the beneficial effect lies in:

[0018] 1. The circuit adopts pure hardware design, and does not need complex software programming and adaptation, so that its application in life is more simple and direct. Users do not need to have professional software knowledge, and only need to connect the circuit to realize real-time monitoring of the power voltage. This design reduces the threshold of use, improves the universality and practicality of the circuit.

[0019] 2. The circuit mainly comprises simple components such as resistors, relays, triodes, LEDs and buzzers, which are easy to buy and low in price on the market. This design not only reduces the cost of the circuit, but also makes the assembly and maintenance of the circuit easier. At the same time, since software support is not needed, the tedious process of software updating and maintenance is also avoided.

[0020] 3. The patent compares the divided voltage generated by the voltage dividing circuit with the stable reference voltage. Through accurate comparison, the circuit can accurately determine whether the power voltage is within the normal range, so as to timely send an alarm signal. This design improves the detection accuracy and reliability of the circuit.

[0021] 4. The circuit makes good use of the voltage divider circuit and operational amplifier circuit, and under the condition of adapting the triode and relay, it can realize the timely alarm circuit under the condition of power supply under-voltage. Similarly, on the basis of this circuit, the power over-voltage alarm monitoring circuit can be realized by slight modification. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is the specific circuit diagram of the power under-voltage alarm monitoring circuit. DETAILED DESCRIPTION

[0023] Referring to Figure 1 The utility model relates to a power under-voltage alarm monitoring circuit, including voltage stabilizing power supply, voltage divider circuit, voltage stabilizing reference circuit, operational amplifier U1, trigger switch circuit, alarm circuit, load, the output end of voltage stabilizing power supply is exported voltage division voltage to the reverse end of operational amplifier U1 through voltage divider circuit, the output end of voltage stabilizing power supply still exports voltage stabilizing reference voltage to the same direction end of operational amplifier U1 through voltage stabilizing reference circuit, wherein the output end of operational amplifier U1 is electrically connected with alarm circuit through trigger switch circuit, and voltage stabilizing power supply still communicates with load through trigger switch circuit, wherein operational amplifier U1 compares voltage division voltage and voltage stabilizing reference voltage, and exports corresponding signal to trigger switch circuit according to the comparison result, and trigger switch circuit further selects to start alarm circuit and disconnects the connection between voltage stabilizing power supply and load.

[0024] Further discussion, the voltage divider circuit includes fourth resistance R4 and fifth resistance R5, wherein one end of fourth resistance R4 is connected with the positive pole of voltage stabilizing power supply, the other end of fourth resistance R4 is connected with one end of fifth resistance R5, and the other end of fifth resistance R5 is grounded.

[0025] Further discussion, voltage stabilizing reference circuit includes voltage stabilizing diode D1, current limiting resistance R3, first resistance R1, wherein one end of current limiting resistance R3 is connected with the positive pole of voltage stabilizing power supply, the other end is connected with the negative pole of voltage stabilizing diode D1, and the positive pole of voltage stabilizing diode D1 is grounded, and the negative pole of voltage stabilizing diode D1 is connected with the same direction end of operational amplifier U1 through first resistance R1.

[0026] In the circuit, the positive pole of the voltage stabilizing diode D1 is connected to the ground, and the negative pole is connected to the positive pole of the voltage stabilizing power supply through the current limiting resistor R3. When the voltage of the voltage stabilizing power supply is high enough, the D1 will be reversely conducted, and the voltage between the two poles will be stabilized at the voltage stabilizing value. The current limiting resistor R3 is used to limit the current passing through the voltage stabilizing diode D1, preventing it from being damaged due to excessive current. The first resistor R1 transmits the voltage at the negative pole of the voltage stabilizing diode D1 (i.e. the voltage stabilizing value) to the same direction terminal (usually marked as "+") of the operational amplifier U1. The first resistor R1 here mainly plays a buffering and isolating role, preventing the operational amplifier U1 from having adverse effects on the voltage stabilizing circuit. At the same time, by adjusting the resistance value of R1, the voltage value transmitted to the same direction terminal of the operational amplifier U1 can also be adjusted to a certain extent to adapt to different application requirements.

[0027] Further discussion, wherein the voltage dividing circuit further comprises a second resistor R2, one end of the second resistor R2 is connected to the node between the fourth resistor R4 and the fifth resistor R5, and the other end of the second resistor R2 is connected to the opposite direction terminal of the operational amplifier U1.

[0028] The addition of the second resistor R2 further refines the function of the voltage dividing circuit. The voltage dividing circuit originally composed of the fourth resistor R4 and the fifth resistor R5 transmits the divided voltage of the output voltage of the voltage stabilizing power supply to the opposite direction terminal of the operational amplifier U1, while the series connection of the second resistor R2 provides an additional adjustment node. By selecting a suitable resistance value of the second resistor R2, the voltage value transmitted to the opposite direction terminal of the operational amplifier U1 can be more accurately controlled, thereby meeting the requirements of specific circuits for the divided voltage. The second resistor R2 can also function to limit current. In the circuit, when the input impedance of the operational amplifier U1 is high, the second resistor R2 can limit the current flowing through the voltage dividing circuit to the opposite direction terminal of the operational amplifier U1, preventing excessive current from damaging the operational amplifier U1. In addition, the second resistor R2 can also reduce current fluctuations caused by power supply voltage fluctuations or load changes to a certain extent, improving the stability of the circuit.

[0029] The main function of the voltage stabilizing reference circuit is to provide a stable and accurate reference voltage for the operational amplifier U1. This reference voltage is the basis for the operation of the power supply undervoltage alarm monitoring circuit, and is used for comparison with the voltage output by the voltage dividing circuit. When the voltage of the voltage stabilizing power supply is normal, the voltage output by the voltage stabilizing reference circuit will remain constant; when the voltage of the voltage stabilizing power supply decreases, the voltage output by the voltage dividing circuit will also decrease accordingly, and when this voltage is lower than the voltage output by the voltage stabilizing reference circuit, the operational amplifier U1 will output a signal to trigger the alarm circuit to work.

[0030] Further elaboration, trigger switch circuit includes a relay, the sixth resistance R6, the first triode Q1, wherein the output of the operational amplifier U1 is connected with the base of the first triode Q1 through the sixth resistance R6, wherein the emitter of the first triode Q1 is grounded, and the collector is connected with the VCC power supply through the relay; Wherein the alarm circuit is also connected with the VCC power supply through the relay to realize power taking, wherein the relay makes the start or the shutdown of the alarm circuit according to the first triode Q1 being in the cut-off or the conducting state.

[0031] The operational amplifier U1 outputs a corresponding signal according to the comparison result by comparing the voltage output by the voltage dividing circuit with the voltage output by the voltage reference circuit. When the voltage of the voltage reference circuit is normal, the voltage output by the voltage dividing circuit is higher than the voltage reference voltage, and the operational amplifier U1 outputs a low level; when the voltage of the voltage reference circuit drops and causes the voltage output by the voltage dividing circuit to be lower than the voltage reference voltage, the operational amplifier U1 outputs a high level.

[0032] The output of the operational amplifier U1 is connected with the base of the first triode Q1 through the sixth resistance R6. When the operational amplifier U1 outputs a high level, the high level signal is added to the base of the first triode Q1 through R6, so that Q1 is turned on. Conversely, when the operational amplifier U1 outputs a low level, Q1 is cut off. When Q1 is turned on, the relay coil is powered, and the contact is actuated. The relay contains multiple contact switches, which can be set to be normally open or normally closed according to the circuit requirements.

[0033] Further elaboration, trigger switch circuit still includes the second diode D2, the collector of the first triode Q1 is connected with the anode of the second diode D2, and the cathode of the second diode D2 is connected with the VCC power supply through the relay.

[0034] In addition, when the first transistor Q1 is in the off state (i.e. no input signal or insufficient input signal to make it conduct), the high resistance state between its collector and emitter. At this time, if the VCC power supply exists surge voltage or transient high voltage, these voltages may be reversed to the collector of the first transistor Q1 through the relay contact. The second diode D2 here plays a role in reverse blocking protection. Since it is a diode, it has unidirectional conductivity, when the voltage from the negative (i.e. the negative of D2) to the positive (i.e. the positive of D2) direction, the diode is off, not conductive. Therefore, when the VCC power supply exists surge voltage or transient high voltage, D2 can prevent these voltages from being reversed to Q1, thereby protecting Q1 from being damaged. In the absence of input signal or weak input signal, the first transistor Q1 needs to be stably kept in the off state. The addition of the second diode D2 helps to enhance this stability. Because of the reverse blocking characteristic of D2, it can ensure that there is no current through the collector when Q1 is off, thereby maintaining the stable off state of Q1. In some cases, if the VCC power supply exists fluctuations or noise, these fluctuations or noise may cause misoperation through the relay contact. The addition of the second diode D2 can reduce the possibility of such misoperation to some extent. Because D2 has unidirectional conductivity, it can prevent reverse current caused by VCC power supply fluctuations or noise from passing through the relay contact, thereby reducing the risk of misoperation.

[0035] Further discussion, the alarm circuit includes a buzzer B1, fault prompt light LED1, the eighth resistor R8, wherein one end of the eighth resistor R8 is connected with the VCC power supply through the relay, and the other end of the eighth resistor R8 is connected with the fault prompt light LED1, and the buzzer B1 is also connected with the VCC power supply through the relay. Further discussion, it also includes a normal working prompt circuit, the normal working prompt circuit includes a normal working prompt light LED2 and a seventh resistor R7, one end of the seventh resistor R7 is connected with the VCC power supply through the relay, and the other end of the seventh resistor R7 is connected with the normal working prompt light LED2, and the relay makes the normal working prompt circuit start or stop according to whether the first transistor Q1 is in the on or off state. Further discussion, the relay includes a No. 1 end, a No. 2 end, a first contact switch K1-1, a second contact switch K1-2 and a third contact switch K1-3, wherein the collector of the first transistor Q1 is connected with the No. 1 end, the No. 2 end is connected with the VCC power supply, the voltage stabilizing power supply is connected with the load through the first contact switch K1-1, the negative electrode of the second diode D2 is connected with the buzzer B1 and the eighth resistor R8 through the second contact switch K1-2, and the negative electrode of the second diode D2 is connected with the seventh resistor R7 through the third contact switch K1-3. Further discussion, the first contact switch K1-1 and the third contact switch K1-3 are normally closed, and the second contact switch K1-2 is normally open.

[0036] Working principle: when the power supply is under-voltage, the operational amplifier U1 output high level, the first transistor Q1 is turned on. The relay action, its second contact switch K1-2 (normally open) is closed, the VCC power supply through the eighth resistance R8 and the fault prompt lamp LED1 and buzzer B1 communication. LED1 light, buzzer B1 alarm sound, prompting the user power under-voltage. The eighth resistance R8 to limit the flow of action, protect LED1 from over-current damage.

[0037] Normal working principle of prompt circuit: when the power supply is normal, the operational amplifier U1 output low level, the first transistor Q1 is cut off. The relay remains in its original state, its third contact switch K1-3 (normally closed) is closed, the VCC power supply through the seventh resistance R7 and normal working prompt lamp LED2 communication. LED2 light, prompting the user power supply is working properly. The seventh resistance R7 also plays a role in limiting the flow of action, protect LED2 from over-current damage.

[0038] The relay structure includes 1, 2, the first contact switch K1-1, the second contact switch K1-2, the third contact switch K1-3.

[0039] 1: the first transistor Q1 of the collector connected to receive Q1 control signal.

[0040] 2: the connection of VCC power supply, for the relay to provide working voltage.

[0041] The first contact switch K1-1: normally closed contact, when the relay does not act, the voltage regulator power supply and load communication.

[0042] The second contact switch K1-2: normally open contact, when the relay action, the closure of the VCC power supply and alarm circuit communication.

[0043] The third contact switch K1-3: normally closed contact, when the relay does not act, the VCC power supply and normal working prompt circuit communication.

[0044] When the power supply is normal: the operational amplifier U1 output low level, Q1 is cut off. The relay does not act, the first contact switch K1-1, the third contact switch K1-3 remain closed state. The voltage regulator power supply through K1-1 and load communication, normal working. VCC power supply through R7 and LED2 communication, LED2 light, prompting the power supply is normal. Alarm circuit (LED1, B1) is powered off, not working.

[0045] When the power supply voltage is low: the power supply voltage is lower than 5V (for example, 4.7V), the voltage of the voltage divider circuit decreases, and the voltage divider circuit divides the voltage again. At this time, because the power supply voltage decreases, the voltage of the inverting terminal also decreases, and the reference voltage remains unchanged. After comparison by the operational amplifier U1, because the voltage of the inverting terminal is lower than the voltage of the non-inverting terminal, the operational amplifier U1 outputs a high level signal. The high level signal of the operational amplifier U1 causes the transistor Q1 to be turned on, and the relay is activated. After the relay is activated, the normally closed contact K1-1 is disconnected, and the connection between the stabilized power supply and the load is cut off; the normally open contact K1-2 is closed, the VCC power supply is connected to the LED1 and the buzzer B1 through R8, the LED1 is lit red, and the buzzer emits an alarm sound; at the same time, the normally closed contact K1-3 is disconnected, and the LED2 is extinguished, indicating that the power supply voltage is low.

[0046] In this embodiment, the voltage divider circuit is composed of resistors R4 (10 kΩ) and R5 (10.6 kΩ) connected in series. When the power supply voltage is 5V, the working principle of the voltage divider circuit is as follows:

[0047] Voltage division: the power supply voltage 5V is applied to R4, and the current flows back to the ground through R4 and R5. Since R4 and R5 are connected in series, the sum of the voltage drops between them is equal to the power supply voltage.

[0048] The voltage of the voltage divider (i.e., the voltage of the inverting terminal of the operational amplifier U1) can be calculated by the formula V out= V in× . Substituting Vin=5V, R4=10kΩ and R5=10.6kΩ into the formula, the voltage of the voltage divider is Vout≈2.427V. At the same time, the stabilized reference circuit provides a stable 2.4V voltage to the non-inverting terminal of the operational amplifier U1 through the stabilized diode D1. The operational amplifier U1 compares the voltages of the inverting terminal (voltage of the voltage divider 2.427V) and the non-inverting terminal (stabilized reference voltage 2.4V). Since the voltage of the inverting terminal is higher than the voltage of the non-inverting terminal, the operational amplifier U1 outputs a low level. The low level signal causes the transistor Q1 to be turned off, and the relay is not activated, maintaining the normally open state. At this time, the relay keeps the normally closed contacts K1-1 and K1-3 closed, the VCC power supply is connected to the LED2 through R7, the LED2 is lit green, indicating that the power supply is working normally; at the same time, the alarm circuit is powered off and does not work.

[0049] When the power supply voltage is low: when the power supply voltage is lower than 5V (for example, 4.7V), the voltage of the voltage divider decreases, and the voltage divider circuit divides the voltage again. At this time, because the power supply voltage decreases, the voltage of the inverting terminal also decreases, and the reference voltage remains unchanged. After comparison by the operational amplifier U1, because the voltage of the inverting terminal is lower than the voltage of the non-inverting terminal, the operational amplifier U1 outputs a high level signal. The high level signal of the operational amplifier U1 causes the transistor Q1 to be turned on, and the relay is activated. After the relay is activated, the normally closed contact K1-1 is disconnected, and the connection between the stabilized power supply and the load is cut off; the normally open contact K1-2 is closed, the VCC power supply is connected to the LED1 and the buzzer B1 through R8, the LED1 is lit red, and the buzzer emits an alarm sound; at the same time, the normally closed contact K1-3 is disconnected, and the LED2 is extinguished, indicating that the power supply voltage is low.

[0050] The beneficial effects of the overall circuit are:

[0051] The circuit adopts pure hardware design, without complex software programming and adaptation, making its application in life more simple and direct. Users do not need to have professional software knowledge, only need to connect the circuit to realize real-time monitoring of power voltage. This design reduces the threshold of use, improves the universality and practicality of the circuit.

[0052] The circuit is mainly composed of simple components such as resistors, relays, transistors, LEDs and buzzers, which are easy to buy and low in price on the market. This design not only reduces the cost of the circuit, but also makes the assembly and maintenance of the circuit easier. At the same time, without software support, it also avoids the tedious process of software update and maintenance.

[0053] This patent requires the comparison of the voltage generated by the voltage divider composed of R5 and R4 with the stable reference voltage between the two ends of the stable voltage diode D1. Through accurate comparison, the circuit can accurately determine whether the power voltage is within the normal range, so as to send alarm signals in time. This design improves the detection accuracy and reliability of the circuit.

[0054] The power under-voltage alarm detection circuit not only realizes real-time monitoring and alarm function of power under-voltage state, but also provides valuable reference and inspiration for the development of other types of detection circuits. First of all, based on the basic principle and structure of the circuit, we can further develop a power over-voltage alarm monitoring circuit. Over-voltage alarm and under-voltage alarm are opposite in logic. Only by adjusting the parameters of the voltage divider and the stable reference circuit appropriately, can the operational amplifier U1 output the corresponding alarm signal when the power voltage exceeds the set threshold. In this way, through simple circuit modification and parameter adjustment, we can realize the protection function of power over-voltage, further widening the application range of the circuit. Secondly, the design idea of the circuit can also be used to develop window comparator. Window comparator is a circuit that can detect whether the input signal is between two set thresholds. Based on this circuit, we can realize the window comparison function of power voltage by adding additional comparator circuit and appropriate logic gate circuit. When the power voltage exceeds the set upper and lower limit range, the circuit can output an alarm signal, so as to realize accurate control and protection of the power voltage.

[0055] In addition, the design idea of this circuit also has wider expansibility. In the field of power management, we can combine this circuit with other power management circuits to achieve comprehensive monitoring and protection of the power supply. For example, we can combine this circuit with a power switch circuit to automatically turn off the power switch when an abnormal power voltage is detected, protecting the load device from damage. At the same time, this circuit can also work with a power stabilizing circuit to achieve precise regulation and stable output of the power voltage. In the field of electronic device protection, this circuit also has broad application prospects. Many electronic devices have strict requirements for the stability of the power voltage, and excessively high or low voltage can cause damage or performance degradation of the device. Therefore, applying this circuit to the power protection of electronic devices can effectively improve the reliability and stability of the device.

[0056] The above embodiments only describe the preferred embodiments of the utility model, and do not limit the scope of the utility model. Without departing from the design spirit of the utility model, various modifications and improvements to the technical solutions of the utility model made by ordinary engineering technicians in the field shall fall within the protection scope determined by the claims of the utility model.

Claims

1. A power supply under-voltage alarm monitoring circuit, characterized by: The voltage stabilizing power supply, the voltage dividing circuit, the voltage reference circuit, the operational amplifier (U1), the trigger switch circuit, the alarm circuit, and the load are connected in series.

2. The under-voltage alarm monitoring circuit of claim 1, wherein: The voltage dividing circuit includes the fourth resistor (R4) and the fifth resistor (R5), wherein one end of the fourth resistor (R4) is connected to the positive pole of the voltage stabilizing power supply, the other end of the fourth resistor (R4) is connected to one end of the fifth resistor (R5), and the other end of the fifth resistor (R5) is grounded.

3. The under-voltage alarm monitoring circuit of claim 1, wherein: The voltage reference circuit includes the voltage stabilizing diode (D1), the current limiting resistor (R3), and the first resistor (R1), wherein one end of the current limiting resistor (R3) is connected to the positive pole of the voltage stabilizing power supply, the other end of the current limiting resistor (R3) is connected to the negative pole of the voltage stabilizing diode (D1), the positive pole of the voltage stabilizing diode (D1) is grounded, and the negative pole of the voltage stabilizing diode (D1) is connected to the same end of the operational amplifier (U1) through the first resistor (R1).

4. The under-voltage alarm monitoring circuit of claim 2, wherein: The voltage dividing circuit further includes the second resistor (R2), wherein one end of the second resistor (R2) is connected to the node between the fourth resistor (R4) and the fifth resistor (R5), and the other end of the second resistor (R2) is connected to the opposite end of the operational amplifier (U1).

5. The under-voltage alarm monitoring circuit of claim 1, wherein: The trigger switch circuit includes the relay, the sixth resistor (R6), and the first transistor (Q1), wherein the output end of the operational amplifier (U1) is connected to the base of the first transistor (Q1) through the sixth resistor (R6), the emitter of the first transistor (Q1) is grounded, and the collector of the first transistor (Q1) is connected to the VCC power supply through the relay.

6. A power supply undervoltage alarm monitoring circuit according to claim 5, characterised in that: The trigger switch circuit further includes the second diode (D2), wherein the collector of the first transistor (Q1) is connected to the positive pole of the second diode (D2), and the negative pole of the second diode (D2) is connected to the VCC power supply through the relay.

7. A power supply undervoltage alarm monitoring circuit as claimed in claim 6, characterized in that: The alarm circuit includes the buzzer (B1), the fault indicator light (LED1), and the eighth resistor (R8), wherein one end of the eighth resistor (R8) is connected to the VCC power supply through the relay, the other end of the eighth resistor (R8) is connected to the fault indicator light (LED1), and the buzzer (B1) is also connected to the VCC power supply through the relay.

8. A power supply undervoltage alarm monitoring circuit as claimed in claim 7, characterized in that: The normal working prompt circuit comprises a normal working prompt lamp (LED2) and a seventh resistor (R7), one end of the seventh resistor (R7) is connected with a VCC power supply through a relay, and the other end of the seventh resistor (R7) is in communication with the normal working prompt lamp (LED2); the relay is started or closed according to whether the first triode (Q1) is in a conducting or a cut-off state.

9. A power supply undervoltage alarm monitoring circuit as claimed in claim 8, characterized in that: The relay comprises a No. 1 end, a No. 2 end, a first contact switch (K1-1), a second contact switch (K1-2) and a third contact switch (K1-3), wherein the collector of the first triode (Q1) is connected with the No. 1 end, the No. 2 end is connected with a VCC power supply, a voltage stabilizing power supply is in communication with a load through the first contact switch (K1-1), the negative electrode of a second diode (D2) is connected with a buzzer (B1) and an eighth resistor (R8) through the second contact switch (K1-2), and the negative electrode of the second diode (D2) is connected with the seventh resistor (R7) through the third contact switch (K1-3).

10. The under-voltage alarm monitoring circuit of claim 9, wherein: The first contact switch (K1-1) and the third contact switch (K1-3) are normally closed, and the second contact switch (K1-2) is normally open.

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