Voltage monitoring alarm circuit
By designing a voltage monitoring and alarm circuit that includes a power supply module, a battery detection module, an alarm control module, an audible and visual alarm module, and a backup alarm module, the problem of the inability of existing battery voltage monitoring and alarm circuits to automatically alarm has been solved. This achieves automatic detection and control of battery voltage, improving the alarm efficiency and reliability of the circuit.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-11
- Publication Date
- 2026-04-07
AI Technical Summary
The existing battery voltage monitoring alarm circuit cannot automatically detect and control alarms, resulting in the inability to provide warnings when the alarm music or alarm malfunctions.
A voltage monitoring and alarm circuit is designed, comprising a power supply module, a battery detection module, an alarm control module, an audible and visual alarm module, a sound detection module, and a backup alarm module. The battery detection module performs overvoltage and undervoltage detection, and controls the audible and visual alarm module to perform audible and visual alarms when an abnormality is detected. The sound detection module performs sound detection, and the backup alarm module provides backup alarms when necessary.
It realizes automatic alarm detection and control of battery voltage, improves the alarm efficiency and reliability of the circuit, and ensures timely warning in abnormal situations.
Smart Images
Figure CN224095908U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of voltage monitoring and alarm technology, specifically a voltage monitoring and alarm circuit. Background Technology
[0002] A battery is an energy conversion and storage device that converts chemical or physical energy into electrical energy through a reaction. To extend battery life and ensure safe charging and discharging control, a voltage monitoring and alarm circuit composed of resistors, comparators, and other components is used. To improve alarm effectiveness, alarm music chips are used to control different alarm sounds. However, current battery voltage monitoring and alarm circuits cannot automatically detect and control alarms, resulting in the inability to function properly when the alarm music chip or alarm malfunctions, thus failing to provide timely warnings. Therefore, improvements are needed. Utility Model Content
[0003] This utility model provides a voltage monitoring alarm circuit to solve the problems mentioned in the background art.
[0004] To achieve the above objectives, this utility model provides the following technical solution:
[0005] A voltage monitoring and alarm circuit includes: a power supply module, a battery detection module, an alarm control module, an audible and visual alarm module, a sound detection module, and a backup alarm module;
[0006] The power module is used to regulate and filter the incoming DC power and output the first power.
[0007] The battery detection module is used to sample the power of the connected battery to be tested. When the sampled signal is greater than the set overvoltage threshold, it outputs a first detection signal, and when the sampled signal is less than the set undervoltage threshold, it outputs a second detection signal.
[0008] An alarm control module, connected to a power module, an audible and visual alarm module, and a battery detection module, is used to transmit first electrical energy to the audible and visual alarm module and provide a first alarm signal when a first detection signal or a second detection signal is received.
[0009] The audible and visual alarm module is connected to the power supply module, the backup power supply module, and the battery detection module. It is used to receive the first electrical energy output by the power supply module and to perform an audible alarm when it receives the first alarm signal or the second control signal output by the backup alarm module. It also performs a visual alarm when it receives the first electrical energy transmitted by the alarm control module and performs an overvoltage display alarm when it receives the first detection signal.
[0010] The sound detection module, connected to the power supply module, is used to receive the first electrical energy and output the first control signal when no sound alarm is detected;
[0011] The backup alarm module is connected to the alarm control module, the sound detection module, and the battery detection module. When receiving the first detection signal or the second detection signal, if the first control signal is received but the first alarm signal is not received, the second control signal will be output. When receiving the first detection signal or the second detection signal, if both the first control signal and the first alarm signal are received, a backup sound alarm will be activated.
[0012] As a further embodiment of this utility model: the power supply module includes a power interface, a first capacitor, a first voltage regulator, and a second capacitor; the alarm control module includes a first thyristor, a third capacitor, a second resistor, and an alarm music chip; the audible and visual alarm module includes a first resistor and a first indicator light.
[0013] Preferably, the first end of the power interface is connected to the third end of the first voltage regulator and is connected to the second end of the power interface, the second end of the first voltage regulator, one end of the second capacitor, the cathode of the first indicator light, one end of the third capacitor, the grounding terminal and the ground terminal of the alarm music chip through the first capacitor. The first end of the first voltage regulator is connected to the other end of the second capacitor and the anode of the first thyristor. The cathode of the first thyristor is connected to the other end of the third capacitor and the power supply terminal of the alarm music chip and is connected to the anode of the first indicator light through the first resistor. The output terminal of the alarm music chip is connected to the backup alarm module. The control terminal of the first thyristor is connected to the first end of the second resistor. The second end of the second resistor is connected to the battery detection module.
[0014] As a further embodiment of this utility model: the battery detection module includes a battery interface, a sixth resistor, a seventh resistor, a first comparator, a second comparator, a second diode, a third diode, a first threshold device, and a second threshold device.
[0015] Preferably, the first end of the battery interface is connected to one end of the seventh resistor, the non-inverting input of the first comparator, and the inverting input of the second comparator via the sixth resistor. The other end of the seventh resistor is connected to the second end of the battery interface. The inverting input of the first comparator and the non-inverting input of the second comparator are respectively connected to the first threshold device and the second threshold device. The output end of the first comparator is connected to the anode of the second diode. The output end of the second comparator is connected to the anode of the third diode. The cathode of the third diode is connected to the cathode of the second diode and the second end of the second resistor.
[0016] As a further improvement of this utility model, the sound and light alarm module also includes a first diode, a first switching transistor, a first speaker, a fifth resistor, and a second indicator light.
[0017] Preferably, the anode of the first diode is connected to the output terminal of the alarm music chip, the cathode of the first diode is connected to the base of the first switching transistor and the backup alarm module, the emitter of the first switching transistor is connected to the cathode of the second indicator light and the second terminal of the power supply port, the collector of the first switching transistor is connected to one end of the first speaker, the other end of the first speaker is connected to the first terminal of the first voltage regulator, and the anode of the second indicator light is connected to the output terminal of the first comparator through the fifth resistor.
[0018] As a further improvement of this utility model: the sound detection module includes a third resistor, a fourth resistor, a second switching transistor, and a first microphone;
[0019] Preferably, the base of the second switching transistor is connected to one end of the first microphone and is connected to the first end of the first voltage regulator and the first end of the fourth resistor through the third resistor. The second end of the fourth resistor is connected to the collector of the second switching transistor and the backup alarm module. The emitter of the second switching transistor is connected to the other end of the first microphone and the second end of the power supply port.
[0020] As a further improvement of this utility model: the backup alarm module includes a fourth diode, a fifth diode, a first logic chip, a second logic chip, a sixth diode, a first inverter, a third logic chip, and a second speaker;
[0021] Preferably, the anode of the fourth diode is connected to the second terminal of the fourth resistor, the cathode of the fourth diode is connected to the cathode of the fifth diode and the A terminal of the first logic chip, the Y terminal of the first logic chip is connected to the anode of the fifth diode, the A terminal of the second logic chip and the A terminal of the third logic chip, the B terminal of the second logic chip is connected to the output terminal of the first inverter, the Y terminal of the second logic chip is connected to the anode of the sixth diode, the cathode of the sixth diode is connected to the base of the first switching transistor, the input terminal of the first inverter is connected to the B terminal of the third logic chip and the output terminal of the alarm music chip, the Y terminal of the third logic chip is connected to one end of the second speaker, and the other end of the second speaker is grounded.
[0022] Compared with the prior art, the beneficial effects of this utility model are as follows: The voltage monitoring alarm circuit of this utility model can use the battery detection module to detect overvoltage and undervoltage of the battery to be tested, and display an alarm when overvoltage or undervoltage occurs. At the same time, the alarm control module will control the audible and visual alarm module to sound an alarm, and the sound detection module will perform sound detection. It will work with the backup alarm module to check whether the alarm control module can perform alarm control normally and whether the audible and visual alarm module can sound an alarm normally. If the alarm control module cannot perform alarm control normally, the backup alarm module will directly control the audible and visual alarm module to sound an alarm. If the audible and visual alarm module cannot sound an alarm, the backup alarm module will perform a backup alarm, thereby improving the alarm efficiency and reliability of the circuit. Attached Figure Description
[0023] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the description of the embodiments of this utility model 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.
[0024] Figure 1 This is a schematic block diagram of a voltage monitoring and alarm circuit provided as an example of the present invention.
[0025] Figure 2 A circuit diagram of a voltage monitoring alarm circuit provided for this utility model embodiment.
[0026] Figure 3 A connection circuit diagram for the backup alarm module provided in this utility model example. Detailed Implementation
[0027] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.
[0028] In one embodiment, see Figure 1 A voltage monitoring alarm circuit includes: a power supply module 1, a battery detection module 2, an alarm control module 3, an audible and visual alarm module 4, a sound detection module 5, and a backup alarm module 6.
[0029] Specifically, power module 1 is used to perform voltage regulation and filtering on the input DC power and output the first power.
[0030] Battery detection module 2 is used to sample the power of the connected battery to be tested. When the sampled signal is greater than the set overvoltage threshold, it outputs a first detection signal, and when the sampled signal is less than the set undervoltage threshold, it outputs a second detection signal.
[0031] The alarm control module 3 is connected to the power module 1, the audible and visual alarm module 4 and the battery detection module 2. When it receives the first detection signal or the second detection signal, it transmits the first electrical energy to the audible and visual alarm module 4 and provides the first alarm signal.
[0032] The audible and visual alarm module 4 is connected to the power supply module 1, the backup power supply module 1 and the battery detection module 2. It is used to receive the first electrical energy output by the power supply module 1 and to perform an audible alarm when it receives the first alarm signal or the second control signal output by the backup alarm module 6. It also performs a visual alarm when it receives the first electrical energy transmitted by the alarm control module 3 and performs an overvoltage display alarm when it receives the first detection signal.
[0033] The sound detection module 5 is connected to the power supply module 1 and is used to receive the first electrical energy and output the first control signal when no sound alarm is detected.
[0034] The backup alarm module 6 is connected to the alarm control module 3, the sound detection module 5 and the battery detection module 2. When receiving the first detection signal or the second detection signal, if the first control signal is received but the first alarm signal is not received, the second control signal will be output. When receiving the first detection signal or the second detection signal, if the first control signal and the first alarm signal are received, a backup sound alarm will be activated.
[0035] In a specific embodiment, the power module 1 can be a power circuit composed of a power interface, a voltage regulator, and a capacitor, which can receive DC power and perform voltage regulation and filtering; the battery detection module 2 can be a battery detection circuit composed of a battery interface, a comparator, a threshold device, etc., which can set overvoltage and undervoltage thresholds, perform overvoltage and undervoltage detection on the connected battery to be tested, and output a high-level signal, namely the first detection signal and the second detection signal, when there is overvoltage or undervoltage; the alarm control module 3 can be an alarm control circuit composed of a capacitor, an alarm music chip, a thyristor, etc., which can control the power transmission state and control the sound and light. The alarm status of alarm module 4; the aforementioned audible and visual alarm module 4 can be composed of a speaker, transistor, indicator light, etc., and can perform sound alarm and light alarm; the aforementioned sound detection module 5 can be composed of a microphone, transistor, resistor, etc., and can perform sound detection; the aforementioned backup alarm module 6 can be composed of a logic chip, diode, speaker, etc., and can determine the working status of alarm control module 3 and sound alarm module based on the input signal, and control audible and visual alarm module 4 to perform sound alarm when alarm control module 3 is abnormal, and perform backup alarm when audible and visual alarm module 4 is abnormal.
[0036] In another embodiment, please refer to Figure 1 , Figure 2 and Figure 3 The power module 1 includes a power interface, a first capacitor C1, a first voltage regulator IC1, and a second capacitor C2; the alarm control module 3 includes a first thyristor S1, a third capacitor C3, a second resistor R2, and an alarm music chip; the sound and light alarm module 4 includes a first resistor R1 and a first indicator light L1.
[0037] Specifically, the first end of the power interface is connected to the third end of the first voltage regulator IC1 and is connected to the second end of the power interface, the second end of the first voltage regulator IC1, one end of the second capacitor C2, the cathode of the first indicator light L1, one end of the third capacitor C3, the ground terminal and the ground terminal of the alarm music chip through the first capacitor C1. The first end of the first voltage regulator IC1 is connected to the other end of the second capacitor C2 and the anode of the first thyristor S1. The cathode of the first thyristor S1 is connected to the other end of the third capacitor C3 and the power supply terminal of the alarm music chip and is connected to the anode of the first indicator light L1 through the first resistor R1. The output terminal of the alarm music chip is connected to the backup alarm module 6. The control terminal of the first thyristor S1 is connected to the first end of the second resistor R2. The second end of the second resistor R2 is connected to the battery detection module 2.
[0038] In a specific embodiment, the first voltage regulator IC1 can be a 7812 voltage regulator; the first thyristor S1 can be a unidirectional thyristor; the first indicator light L1 can be an LED; and the alarm music chip can be a KD9561 chip, but is not limited to the KD9561 chip.
[0039] Furthermore, the battery detection module 2 includes a battery interface, a sixth resistor R6, a seventh resistor R7, a first comparator A1, a second comparator A2, a second diode D2, a third diode D3, a first threshold device, and a second threshold device.
[0040] Specifically, the first end of the battery interface is connected to one end of the seventh resistor R7, the non-inverting input of the first comparator A1, and the inverting input of the second comparator A2 via the sixth resistor R6. The other end of the seventh resistor R7 is connected to the second end of the battery interface. The inverting input of the first comparator A1 and the non-inverting input of the second comparator A2 are respectively connected to the first threshold device and the second threshold device. The output end of the first comparator A1 is connected to the anode of the second diode D2. The output end of the second comparator A2 is connected to the anode of the third diode D3. The cathode of the third diode D3 is connected to the cathode of the second diode D2 and the second end of the second resistor R2.
[0041] In a specific embodiment, both the first comparator A1 and the second comparator A2 can be selected as LM358 comparators; both the first threshold device and the second threshold device can be composed of a reference power supply and a resistor, respectively providing an overvoltage threshold and an undervoltage threshold.
[0042] Furthermore, the audible and visual alarm module 4 also includes a first diode D1, a first switching transistor V1, a first speaker BL1, a fifth resistor R5, and a second indicator light L2;
[0043] Specifically, the anode of the first diode D1 is connected to the output terminal of the alarm music chip, the cathode of the first diode D1 is connected to the base of the first switching transistor V1 and the backup alarm module 6, the emitter of the first switching transistor V1 is connected to the cathode of the second indicator light L2 and the second terminal of the power supply port, the collector of the first switching transistor V1 is connected to one end of the first speaker BL1, the other end of the first speaker BL1 is connected to the first terminal of the first voltage regulator, and the anode of the second indicator light L2 is connected to the output terminal of the first comparator A1 through the fifth resistor R5.
[0044] In a specific embodiment, the second indicator L2 can be an LED; the first switching transistor V1 can be an NPN transistor.
[0045] Furthermore, the sound detection module 5 includes a third resistor R3, a fourth resistor R4, a second switch V2, and a first microphone MIC;
[0046] Specifically, the base of the second switch transistor V2 is connected to one end of the first microphone MIC and is connected to the first end of the first voltage regulator IC1 and the first end of the fourth resistor R4 through the third resistor R3. The second end of the fourth resistor R4 is connected to the collector of the second switch transistor V2 and the backup alarm module 6. The emitter of the second switch transistor V2 is connected to the other end of the first microphone MIC and the second end of the power supply port.
[0047] In a specific embodiment, the second switching transistor V2 can be an NPN transistor.
[0048] Furthermore, the backup alarm module 6 includes a fourth diode D4, a fifth diode D5, a first logic chip J1, a second logic chip J2, a sixth diode D6, a first inverter INV1, a third logic chip J3, and a second speaker BL2.
[0049] Specifically, the anode of the fourth diode D4 is connected to the second terminal of the fourth resistor R4, the cathode of the fourth diode D4 is connected to the cathode of the fifth diode D5 and the A terminal of the first logic chip J1, the Y terminal of the first logic chip J1 is connected to the anode of the fifth diode D5, the A terminal of the second logic chip J2 and the A terminal of the third logic chip J3, the B terminal of the second logic chip J2 is connected to the output terminal of the first inverter INV1, the Y terminal of the second logic chip J2 is connected to the anode of the sixth diode D6, the cathode of the sixth diode D6 is connected to the base of the first switching transistor V1, the input terminal of the first inverter INV1 is connected to the B terminal of the third logic chip J3 and the output terminal of the alarm music chip, the Y terminal of the third logic chip J3 is connected to one end of the second speaker BL2, and the other end of the second speaker BL2 is grounded.
[0050] In a specific embodiment, the first logic chip J1, the second logic chip J2, and the third logic chip J3 can all be AND gate chips, wherein the first logic chip J1, together with the fourth diode D4 and the fifth diode D5, can perform high-level self-locking; the first inverter INV1 can be a NOT gate chip.
[0051] In this embodiment, a voltage monitoring alarm circuit receives DC power through a power interface. A first voltage regulator IC1, a first capacitor C1, and a second capacitor C2 perform voltage regulation and filtering to output the first electrical energy. A battery interface is connected to the power supply terminal of the battery to be tested. A sixth resistor R6 and a seventh resistor R7 sample the battery's charge level. When the sampled signal exceeds the overvoltage threshold set by a first threshold device, the first comparator A1 outputs a high level, i.e., a first detection signal, illuminating the second indicator L2 and turning on the first thyristor S1. Alternatively, when the sampled signal falls below the undervoltage threshold set by a second threshold device, the second comparator A2 outputs a second detection signal, controlling the first thyristor S1 to turn on. The first thyristor S1 then transmits the first electrical energy to the alarm music chip. The first switch V1 is turned on, the first speaker BL1 sounds an alarm, and the first indicator light L1 displays an alarm. When the first detection signal or the second detection signal is output, if the first microphone MIC does not detect an alarm sound, the first logic chip J1, in conjunction with the fourth diode D4 and the fifth diode D5, performs a high-level self-locking. If the first switch V1 cannot be turned on due to a fault in the alarm music chip, the first inverter INV1 will output a high level, causing the second logic chip J2 to directly trigger the first switch V1 to turn on, controlling the first speaker BL1 to sound an alarm. If the alarm music chip is normal and can trigger the first switch V1 to turn on, but no alarm sound is still detected, the third logic chip J3 will trigger the second speaker BL2 to sound an alarm.
[0052] It will be apparent to those skilled in the art that this invention is not limited to the details of the exemplary embodiments described above, and that it can be implemented in other specific forms without departing from the spirit or essential characteristics of this invention. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of this invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within this invention. No reference numerals in the claims should be construed as limiting the scope of the claims.
[0053] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.
Claims
1. A voltage monitoring and alarm circuit, characterized in that, The voltage monitoring and alarm circuit includes: a power supply module, a battery detection module, an alarm control module, an audible and visual alarm module, a sound detection module, and a backup alarm module; The power module is used to perform voltage regulation and filtering on the input DC power and output the first power. The battery detection module is used to sample the power of the connected battery to be tested. When the sampled signal is greater than a set overvoltage threshold, it outputs a first detection signal, and when the sampled signal is less than a set undervoltage threshold, it outputs a second detection signal. The alarm control module is connected to the power module, the audible and visual alarm module and the battery detection module. When it receives the first detection signal or the second detection signal, it transmits the first electrical energy to the audible and visual alarm module and provides the first alarm signal. The audible and visual alarm module is connected to the power supply module, the backup power supply module, and the battery detection module. It is used to receive the first electrical energy output by the power supply module and to perform an audible alarm when it receives the first alarm signal or the second control signal output by the backup alarm module. It also performs a visual alarm when it receives the first electrical energy transmitted by the alarm control module and performs an overvoltage display alarm when it receives the first detection signal. The sound detection module is connected to the power module and is used to receive the first electrical energy and output the first control signal when no sound alarm is detected. The backup alarm module is connected to the alarm control module, the sound detection module, and the battery detection module. When receiving a first detection signal or a second detection signal, if it receives a first control signal but does not receive a first alarm signal, it will output a second control signal. When receiving a first detection signal or a second detection signal, if it receives both the first control signal and the first alarm signal, it will activate a backup sound alarm.
2. The voltage monitoring alarm circuit according to claim 1, characterized in that, The power module includes a power interface, a first capacitor, a first voltage regulator, and a second capacitor; the alarm control module includes a first thyristor, a third capacitor, a second resistor, and an alarm music chip; the audible and visual alarm module includes a first resistor and a first indicator light. The first end of the power interface is connected to the third end of the first voltage regulator and is connected to the second end of the power interface, the second end of the first voltage regulator, one end of the second capacitor, the cathode of the first indicator light, one end of the third capacitor, the grounding terminal and the ground terminal of the alarm music chip through the first capacitor. The first end of the first voltage regulator is connected to the other end of the second capacitor and the anode of the first thyristor. The cathode of the first thyristor is connected to the other end of the third capacitor and the power supply terminal of the alarm music chip and is connected to the anode of the first indicator light through the first resistor. The output terminal of the alarm music chip is connected to the backup alarm module. The control terminal of the first thyristor is connected to the first end of the second resistor. The second end of the second resistor is connected to the battery detection module.
3. The voltage monitoring alarm circuit according to claim 2, characterized in that, The battery detection module includes a battery interface, a sixth resistor, a seventh resistor, a first comparator, a second comparator, a second diode, a third diode, a first threshold device, and a second threshold device. The first end of the battery interface is connected to one end of the seventh resistor, the non-inverting input of the first comparator, and the inverting input of the second comparator via the sixth resistor. The other end of the seventh resistor is connected to the second end of the battery interface. The inverting input of the first comparator and the non-inverting input of the second comparator are respectively connected to the first threshold device and the second threshold device. The output end of the first comparator is connected to the anode of the second diode. The output end of the second comparator is connected to the anode of the third diode. The cathode of the third diode is connected to the cathode of the second diode and the second end of the second resistor.
4. A voltage monitoring alarm circuit according to claim 3, characterized in that, The audible and visual alarm module also includes a first diode, a first switching transistor, a first speaker, a fifth resistor, and a second indicator light; The anode of the first diode is connected to the output terminal of the alarm music chip, the cathode of the first diode is connected to the base of the first switching transistor and the backup alarm module, the emitter of the first switching transistor is connected to the cathode of the second indicator light and the second terminal of the power supply port, the collector of the first switching transistor is connected to one end of the first speaker, the other end of the first speaker is connected to the first terminal of the first voltage regulator, and the anode of the second indicator light is connected to the output terminal of the first comparator through the fifth resistor.
5. A voltage monitoring alarm circuit according to claim 4, characterized in that, The sound detection module includes a third resistor, a fourth resistor, a second switching transistor, and a first microphone; The base of the second switching transistor is connected to one end of the first microphone and is connected to the first end of the first voltage regulator and the first end of the fourth resistor through the third resistor. The second end of the fourth resistor is connected to the collector of the second switching transistor and the backup alarm module. The emitter of the second switching transistor is connected to the other end of the first microphone and the second end of the power supply port.
6. A voltage monitoring alarm circuit according to claim 5, characterized in that, The backup alarm module includes a fourth diode, a fifth diode, a first logic chip, a second logic chip, a sixth diode, a first inverter, a third logic chip, and a second speaker; The anode of the fourth diode is connected to the second terminal of the fourth resistor, the cathode of the fourth diode is connected to the cathode of the fifth diode and the A terminal of the first logic chip, the Y terminal of the first logic chip is connected to the anode of the fifth diode, the A terminal of the second logic chip and the A terminal of the third logic chip, the B terminal of the second logic chip is connected to the output terminal of the first inverter, the Y terminal of the second logic chip is connected to the anode of the sixth diode, the cathode of the sixth diode is connected to the base of the first switching transistor, the input terminal of the first inverter is connected to the B terminal of the third logic chip and the output terminal of the alarm music chip, the Y terminal of the third logic chip is connected to one end of the second speaker, and the other end of the second speaker is grounded.