Frequency-selecting voltage-stabilizing circuit, fire-fighting telephone extension and fire-fighting telephone system

Abstract

The utility model provides a frequency-selecting voltage-stabilizing circuit, a fire-fighting telephone extension and a fire-fighting telephone system, and belongs to the technical field of fire-fighting telephones. According to the utility model, two functions of frequency selection and voltage stabilization are combined, and the frequency selection network module receives an amplified fire-fighting telephone host signal and outputs a high-frequency modulation signal with a fixed frequency to the single-chip microcomputer of the fire-fighting telephone extension; and the direct-current voltage stabilization module takes the direct-current voltage of the frequency-selecting network module as a voltage source, outputs voltage-stabilized direct current, and supplies power to a single-chip microcomputer of the fire-fighting extension telephone. In addition, the voltage stabilizing circuit can be used as a current-limiting resistor of the frequency-selecting circuit and participates in adjusting the center frequency of the frequency-selecting circuit. Compared with the power consumption of two independent functional circuits of frequency selection and voltage stabilization, the voltage stabilization part takes the direct-current voltage of the frequency selection part as a voltage source, the parts participating in frequency modulation and voltage stabilization do not need to be independently provided with a power supply, and the fixed power consumption of the two parts after combination is reduced, so that the overall power consumption of the fire-fighting telephone extension is reduced, and the performance of the fire-fighting telephone extension is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of fire-fighting telephones, in particular to a frequency-selective voltage-stabilizing circuit, a fire-fighting telephone extension and a fire-fighting telephone system. Background Art

[0002] The fire telephone system is an important part of the fire communication network. It provides communication support for fire alarm, emergency evacuation, command and dispatch, and on-site rescue. The fire telephone system usually consists of a fire telephone host and multiple fire telephone extensions. The communication method between the fire telephone host and the fire telephone extension is usually two-bus communication.

[0003] The two-bus fire telephone system realizes power supply and data communication on the same pair of lines. The DC power supply provided by the fire telephone host to the fire telephone extension, the voice signal when the fire telephone host talks with the fire telephone extension, and the high-frequency modulation control command of the fire telephone host to control the fire telephone extension are all transmitted through the telephone line.

[0004] The internal circuit of the fire telephone extension amplifies the signal of the fire telephone host, and selects and analyzes the communication signal belonging to the extension, such as voice signal and control signal. The single chip microcomputer of the fire extension further processes the selected communication signal. The overall power consumption of the existing two-bus fire telephone extension is relatively large. Utility Model Content

[0005] The utility model provides a frequency-selective voltage-stabilizing circuit, a fire-fighting telephone extension and a fire-fighting telephone system, so as to solve the problem that the existing two-bus system fire-fighting telephone extension has a large overall power consumption.

[0006] In the first aspect, the utility model provides a frequency selection and voltage stabilization circuit, comprising: a common collector amplifier module, a frequency selection network module and a DC voltage stabilization module. The power supply end of the common collector amplifier module is connected to a DC power supply, the signal input end receives a fire telephone host signal, and the signal output end outputs the amplified fire telephone host signal. The first end of the frequency selection network module is connected to the signal output end of the common collector amplifier module, and the second end is used to connect to the ground end. The first end is also used to output a frequency selection signal to a single-chip microcomputer of a fire telephone extension, wherein the frequency of the frequency selection signal is the same as the center frequency of the frequency selection network module. The DC voltage stabilization module is arranged between the second end of the frequency selection network module and the ground end. The power supply end of the DC voltage stabilization module is connected to the second end of the frequency selection network module, and the other end of the DC voltage stabilization module is connected to the ground end. The power supply end is also used to output a stabilized DC and power the single-chip microcomputer of the fire telephone extension.

[0007] In a possible implementation, the frequency selection network module includes a frequency selection inductor and a frequency selection capacitor connected in parallel, wherein the first ends of the frequency selection inductor and the frequency selection capacitor are connected to the signal output end of the common collector amplifier module, and the second ends are connected to the power supply end of the DC voltage regulator module.

[0008] In a possible implementation, the frequency selection network module includes a first DC blocking capacitor, which is arranged between the frequency selection inductor and the first end of the frequency selection capacitor and the single chip microcomputer of the fire telephone extension.

[0009] In a possible implementation, the DC voltage regulation module includes a first output voltage regulating resistor, a second output voltage regulating resistor, an adjustable voltage regulator, a first output filter capacitor, and a second output filter capacitor. The first output voltage regulating resistor is connected in series with the second output voltage regulating resistor, the input end of the first output voltage regulating resistor is connected to the power supply end of the DC voltage regulation module, and the output end of the second output voltage regulating resistor in series is connected to the ground end. The cathode of the adjustable voltage regulator is connected to the power supply end, the anode is connected to the ground end, and the reference end is connected between the first output voltage regulating resistor and the second output voltage regulating resistor. The positive end of the first output filter capacitor and the second output filter capacitor is connected to the power supply end, and the negative end is connected to the ground end.

[0010] In a possible implementation, the common collector amplifier module includes a triode, a base bias resistor and a collector bias resistor. The base of the triode is connected to a DC power supply through the base bias resistor.

[0011] The collector of the transistor is connected to a DC power supply via a collector bias resistor. The base of the transistor is also connected to the signal input end of the common collector amplifier module. The emitter of the transistor serves as the signal output end of the common collector amplifier module.

[0012] In a possible implementation, the DC power supply is a constant current source. The input end of the DC power supply is connected to the fire telephone host signal, and the output end outputs DC.

[0013] In a possible implementation, the common collector amplification module further includes a second DC blocking capacitor, which is arranged between the base of the transistor and the signal input terminal of the common collector amplification module.

[0014] In a possible implementation, a fire telephone extension demodulation module is further included. The fire telephone extension demodulation module is arranged between the first end of the frequency selection network module and the single chip microcomputer of the fire telephone extension.

[0015] In a second aspect, the utility model provides a fire telephone extension, comprising the frequency selection and voltage stabilization circuit described in any one of the first aspects.

[0016] In a third aspect, the utility model provides a fire telephone system, comprising the fire telephone extension described in the second aspect.

[0017] The utility model provides a frequency selection and voltage stabilization circuit, a fire telephone extension and a fire telephone system. The utility model combines the functions of frequency selection and voltage stabilization. The frequency selection network module receives the amplified fire telephone host signal and outputs a high-frequency modulation signal with a fixed frequency to the single-chip microcomputer of the fire telephone extension. The DC voltage stabilization module uses the DC voltage of the frequency selection network module as a voltage source, outputs a regulated DC voltage, and supplies power to the single-chip microcomputer of the fire telephone extension. In addition, the voltage stabilization circuit can also be used as a current limiting resistor of the frequency selection circuit and participate in adjusting the center frequency of the frequency selection circuit. Compared with the power consumption of two independent functional circuits of frequency selection and voltage stabilization, the voltage stabilization part uses the DC voltage of the frequency selection part as a voltage source and participates in frequency modulation. The voltage stabilization part does not need to be set up with a separate power supply. The fixed power consumption of the two combined parts is reduced, thereby reducing the overall power consumption of the fire telephone extension and improving the performance of the fire telephone extension. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the utility model, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0019] Figure 1 It is a structural diagram of a two-bus fire telephone system provided by an embodiment of the utility model;

[0020] Figure 2 It is a structural schematic diagram of a frequency-selective voltage-stabilizing circuit provided in an embodiment of the utility model. DETAILED DESCRIPTION

[0021] In order to enable people in the technical field to better understand the present solution, the technical solution in the embodiment of the present solution will be clearly described below in conjunction with the drawings in the embodiment of the present solution. Obviously, the described embodiment is an embodiment of a part of the present solution, not all of the embodiments. Based on the embodiments in the present solution, all other embodiments obtained by ordinary technicians in the field without creative work should fall within the scope of protection of the present solution.

[0022] The term "including" and any other variations in the specification and claims of this solution and the above drawings mean "including but not limited to", and is intended to cover non-exclusive inclusions and is not limited to the examples listed in the text. In addition, the terms "first" and "second" are used to distinguish different objects, not to describe a specific order.

[0023] The following is a detailed description of the implementation of the present invention in conjunction with the specific drawings:

[0024] Figure 1 This is a schematic diagram of the structure of the two-bus fire telephone system provided by the embodiment of the utility model. Figure 1 The fire telephone host is connected to the fire telephone extension through a telephone line. Exemplarily, the fire telephone extension includes a frequency selection and voltage stabilization circuit and a single chip microcomputer.

[0025] The inventor of the present application discovered during research and development that in the traditional method, the frequency selection circuit and the voltage stabilization circuit in the fire telephone extension are two independent circuits. For example, the frequency selection circuit is only responsible for selecting and parsing the communication signal belonging to this extension, and outputting the communication signal of this extension to the single-chip microcomputer. The voltage stabilization circuit is connected to a separate power supply and outputs the regulated voltage to the single-chip microcomputer. As a result, the two independent frequency selection circuits and voltage stabilization circuits cause the overall power consumption of the fire telephone extension to be relatively large.

[0026] The embodiment of the utility model provides a frequency selection and voltage stabilization circuit which combines the two functions of frequency selection and voltage stabilization to solve the problem of large overall power consumption of the existing two-bus fire telephone extension.

[0027] Figure 2 This is a schematic diagram of a frequency-selective voltage-stabilizing circuit provided by an embodiment of the utility model. Figure 2 , the circuit includes: a common collector amplifier module, a frequency selection network module and a DC voltage regulator module. The power supply end of the common collector amplifier module is connected to a DC power supply, the signal input end receives the fire telephone host signal, and the signal output end outputs the amplified fire telephone host signal. The first end of the frequency selection network module is connected to the signal output end of the common collector amplifier module, the second end is used to connect to the ground end, and the first end is also used to output the frequency selection signal to the single-chip microcomputer of the fire telephone extension, wherein the frequency of the frequency selection signal is the same as the center frequency of the frequency selection network module. The DC voltage regulator module is arranged between the second end of the frequency selection network module and the ground end. The power supply end of the DC voltage regulator module is connected to the second end of the frequency selection network module, and the other end of the DC voltage regulator module is connected to the ground end. The power supply end is also used to output a stabilized DC and power the single-chip microcomputer of the fire telephone extension.

[0028] In some embodiments, the common collector amplifier module is also called a common collector circuit or a triode common collector circuit. The common collector amplifier module is used to amplify the signal of the fire telephone host. Exemplarily, the common collector circuit can play the role of impedance matching as an input stage circuit.

[0029] In some embodiments, the power supply end of the common-collector amplifier module is connected to a DC power supply, the signal input end receives a fire telephone host signal, and the signal output end outputs an amplified fire telephone host signal.

[0030] It should be noted that the common collector amplifier module generally includes a signal input terminal, a signal output terminal and a power supply terminal. For example, the signal input terminal is the base of the transistor, the signal output terminal is the emitter of the transistor, and the power supply terminal is the collector of the transistor.

[0031] Exemplarily, the DC power supply may be part of the fire telephone extension. For example, the DC power supply generates DC based on the DC component in the fire telephone host signal. In another exemplary embodiment, the DC power supply may also be a separately provided power supply.

[0032] It should be noted that the fire telephone host signal is a mixed signal, including a DC component and an AC component. For example, the DC component is used for DC power feeding, and the AC component is used to transmit voice signals and control signals. Exemplarily, the DC component can be filtered by a capacitor, and the AC part is retained, so that the common collector amplifier module only amplifies the AC component.

[0033] It should be further explained that the AC component contains signals of multiple frequencies, corresponding to multiple extensions, and each extension corresponds to a preset frequency. The fire telephone extension needs to select the frequency to parse the communication signal belonging to the extension. The frequency selection function is implemented specifically through the following frequency selection network module.

[0034] In some embodiments, the frequency-selective network module receives the fire telephone host signal and frequency-selectively parses the communication signal belonging to the extension, such as voice signal and control signal.

[0035] Exemplarily, the frequency selection network module is a parallel grounding structure, that is, one end is connected to the signal output end of the collector amplifier module, and the other end is grounded. The signal input end and the signal output end of the frequency selection network module are the same port.

[0036] Specifically, in some embodiments, a first end of the frequency selection network module is connected to a signal output end of the common collector amplifier module, and a second end is used to connect to a ground end.

[0037] Furthermore, in some embodiments, the first end of the frequency-selective network module is also used to output a frequency-selective signal to the single-chip microcomputer of the fire telephone extension, wherein the frequency of the frequency-selective signal is the same as the center frequency of the frequency-selective network module.

[0038] It should be noted that the frequency selection network module only allows the output of signals with the same center frequency as it. The frequency selection network module receives the amplified fire telephone host signal and outputs a high-frequency modulation signal with a fixed frequency to the single-chip microcomputer of the fire telephone extension. For example, in the end, only the high-frequency modulation control command output of the fire telephone host to control the fire telephone extension is output at the signal output end. After receiving the frequency selection signal, the single-chip microcomputer of the fire telephone extension further processes it to demodulate the voice signal or control signal. For example, it is input to the single-chip microcomputer through the demodulation circuit inside the fire telephone extension to realize the control of the fire telephone extension by the fire telephone host.

[0039] The ground terminal of the frequency selection network module is usually directly grounded. However, in the present application, the DC voltage of the frequency selection network module is used as the voltage source of the DC voltage stabilizing module to reduce the overall power consumption. The following embodiments illustrate the specific implementation of the DC voltage stabilizing module.

[0040] In some embodiments, the DC voltage regulator module inputs a DC voltage source and outputs a regulated DC to power the microcontroller of the fire telephone extension.

[0041] Specifically, in some embodiments, the DC voltage stabilizing module is disposed between the second end of the frequency selection network module and the ground end. That is, the second end of the frequency selection network module is not directly grounded, but is grounded through the DC voltage stabilizing module.

[0042] Furthermore, in some embodiments, the power supply end of the DC voltage stabilizing module is connected to the second end of the frequency selection network module, and the other end of the DC voltage stabilizing module is connected to the ground end.

[0043] It should be noted that the DC voltage regulator module includes a power supply terminal and a ground terminal. The power supply terminal receives a DC voltage source and outputs a stabilized DC after voltage stabilization. The ground terminal of the DC voltage regulator module is directly grounded.

[0044] Furthermore, in some embodiments, the power supply terminal of the DC voltage regulator module is also used to output a regulated DC voltage to power the microcontroller of the fire telephone extension. Exemplarily, the DC voltage regulator module outputs a 3.3V voltage as a 3.3V regulated power supply for the low-power microcontroller.

[0045] The embodiment of the utility model provides a frequency selection and voltage stabilization circuit, which combines the functions of frequency selection and voltage stabilization. The frequency selection network module receives the amplified fire telephone host signal and outputs a high-frequency modulation signal with a fixed frequency to the single-chip microcomputer of the fire telephone extension. The DC voltage stabilization module uses the DC voltage of the frequency selection network module as a voltage source, outputs a regulated DC voltage, and supplies power to the single-chip microcomputer of the fire telephone extension. In addition, the voltage stabilization circuit can also be used as a current limiting resistor of the frequency selection circuit and participate in adjusting the center frequency of the frequency selection circuit. Compared with the power consumption of two independent functional circuits of frequency selection and voltage stabilization, the voltage stabilization part uses the DC voltage of the frequency selection part as a voltage source and participates in frequency modulation. The voltage stabilization part does not need to be set up with a separate power supply. The fixed power consumption of the two combined parts is reduced, thereby reducing the overall power consumption of the fire telephone extension and improving the performance of the fire telephone extension.

[0046] The advantage of a frequency selection and voltage stabilization circuit provided by the embodiment of the utility model is that the frequency selection and voltage stabilization are combined, and the fixed power consumption of the two parts after the combination is reduced compared with the power consumption of two independent functional circuits. After the circuit is combined, the frequency selection circuit and the voltage stabilization circuit are series circuits, and the currents of the two are the same, which consumes less power than if they were set separately.

[0047] It should be noted that the triode common collector circuit itself needs to provide bias current to work properly, which is the fixed power consumption of the fire telephone extension. The microcontroller, as the core component of the fire telephone extension, also needs fixed power consumption. Using part of the bias current of the triode common collector circuit as the power supply for the microcontroller reduces the overall power consumption of the fire telephone extension.

[0048] The embodiment of the utility model provides a frequency selection and voltage stabilization circuit, which combines the frequency selection circuit and the voltage stabilization circuit, can receive a high-frequency modulation signal with a fixed frequency selected, and provide a 3.3V regulated power supply for an internal low-power single-chip microcomputer at the same time.

[0049] Reference Figure 2 In a possible implementation, the frequency selection network module includes a frequency selection inductor L1 and a frequency selection capacitor C1 connected in parallel. The first ends of the frequency selection inductor L1 and the frequency selection capacitor C1 are connected to the signal output end of the common collector amplifier module, and the second ends are connected to the power supply end of the DC voltage regulator module.

[0050] Exemplarily, the two ends of the frequency-selective inductor L1 and the frequency-selective capacitor C1 are connected in parallel, that is, the first end of the frequency-selective inductor L1 is the same as the first end of the frequency-selective capacitor C1, and the second end of the frequency-selective inductor L1 is the same as the second end of the frequency-selective capacitor C1.

[0051] Exemplarily, the first ends of the frequency-selective inductor L1 and the frequency-selective capacitor C1 are connected to the emitter E of the triode of the common-collector amplifier module.

[0052] Exemplarily, the inductance value of the frequency-selective inductor L1 and the capacitance value of the frequency-selective capacitor C1 jointly affect the center frequency of the frequency-selective network module.

[0053] The frequency selection network module of the utility model is composed of an LC parallel frequency selection network formed by an inductor and a capacitor, and has a small impedance to a voice signal, which is equivalent to being directly connected to GND.

[0054] Reference Figure 2 In a possible implementation, the frequency selection network module includes a first DC blocking capacitor, which is arranged between the frequency selection inductor and the first end of the frequency selection capacitor and the single chip microcomputer of the fire telephone extension.

[0055] Exemplarily, the first DC blocking capacitor C2 is an output coupling capacitor, which functions to isolate DC signals and only allow AC signals to be output.

[0056] Reference Figure 2 In a possible implementation, the DC voltage regulation module includes a first output voltage regulating resistor R1, a second output voltage regulating resistor R2, an adjustable voltage regulator U1, a first output filter capacitor E1 and a second output filter capacitor C3.

[0057] In some embodiments, the first output voltage regulating resistor R1 is connected in series with the second output voltage regulating resistor R2, the input end of the first output voltage regulating resistor R1 is connected to the power supply end of the DC voltage regulating module, and the output end of the second output voltage regulating resistor R2 is connected to the ground end.

[0058] In some embodiments, the cathode of the adjustable voltage regulator U1 is connected to the power supply terminal, the anode is connected to the ground terminal, and the reference terminal is connected between the first output voltage regulating resistor R1 and the second output voltage regulating resistor R2.

[0059] Exemplarily, the adjustable regulator U1 includes three ports, port 1 is a reference port, port 2 is an anode port, and port 3 is a cathode port.

[0060] Exemplarily, the model of the adjustable voltage regulator U1 is TL431.

[0061] In some embodiments, the positive terminals of the first output filter capacitor E1 and the second output filter capacitor C3 are connected to the power supply terminal, and the negative terminals are connected to the ground terminal.

[0062] Reference Figure 2 In a possible implementation, the common collector amplifier module includes a transistor T1, a base bias resistor and a collector bias resistor. The base B of the transistor T1 is connected to a DC power supply through a base bias resistor R3. The collector C of the transistor T1 is connected to a DC power supply through a collector bias resistor R4. The base B of the transistor T1 is also connected to a signal input terminal of the common collector amplifier module. The emitter E of the transistor T1 serves as a signal output terminal of the common collector amplifier module.

[0063] Exemplarily, the model of transistor T1 is 5551.

[0064] In a possible implementation, the DC power supply is a constant current source, the input end of the DC power supply is connected to the fire telephone host signal, and the output end outputs DC.

[0065] Exemplarily, the constant current source can isolate AC and pass DC, the input end is connected to the fire telephone host signal, and the output end outputs DC.

[0066] In a possible implementation, the common collector amplifier module further includes a second DC blocking capacitor C4. The second DC blocking capacitor C4 is arranged between the base of the transistor and the signal input terminal of the common collector amplifier module.

[0067] Exemplarily, the second DC blocking capacitor C4 is an input coupling capacitor, which is used to isolate DC signals and only allow AC signals to be input.

[0068] In a possible implementation, a fire telephone extension demodulation module is also included. The fire telephone extension demodulation module is arranged between the first end of the frequency selection network module and the single chip microcomputer of the fire telephone extension.

[0069] An embodiment of the utility model provides a fire telephone extension, comprising a frequency selection and voltage stabilization circuit as in any possible implementation manner described above.

[0070] The embodiment of the utility model provides a fire telephone system, comprising the fire telephone extension.

[0071] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A frequency-selective voltage-stabilizing circuit, It is characterized in that include: Common collector amplifier module, frequency selection network module and DC voltage regulator module; The power supply end of the common collector amplifier module is connected to a DC power supply, the signal input end receives a fire telephone host signal, and the signal output end outputs an amplified fire telephone host signal; The first end of the frequency selection network module is connected to the signal output end of the common collector amplifier module, and the second end is used to connect to the ground end. The first end is also used to output a frequency selection signal to the single chip microcomputer of the fire telephone extension, wherein the frequency of the frequency selection signal is the same as the center frequency of the frequency selection network module; The DC voltage stabilizing module is arranged between the second end of the frequency selection network module and the ground end; the power supply end of the DC voltage stabilizing module is connected to the second end of the frequency selection network module, and the other end of the DC voltage stabilizing module is connected to the ground end, and the power supply end is also used to output stabilized DC and power the microcontroller of the fire telephone extension.

2. The frequency-selective voltage-stabilizing circuit according to claim 1, It is characterized in that The frequency selection network module includes a frequency selection inductor and a frequency selection capacitor connected in parallel; The first ends of the frequency-selective inductor and the frequency-selective capacitor are connected to the signal output end of the common-collector amplifier module, and the second ends are connected to the power supply end of the DC voltage stabilization module.

3. The frequency-selective voltage-stabilizing circuit according to claim 2, It is characterized in that The frequency selection network module includes a first DC blocking capacitor; The DC blocking capacitor is arranged between the first end of the frequency-selective inductor and the frequency-selective capacitor and the single-chip microcomputer of the fire telephone extension.

4. The frequency-selective voltage-stabilizing circuit according to claim 1, It is characterized in that The DC voltage stabilization module includes a first output voltage regulating resistor, a second output voltage regulating resistor, an adjustable voltage stabilizer, a first output filter capacitor and a second output filter capacitor; The first output voltage regulating resistor is connected in series with the second output voltage regulating resistor, the input end of the first output voltage regulating resistor is connected to the power supply end of the DC voltage stabilizing module, and the output end of the second output voltage regulating resistor in series is connected to the ground end; The cathode of the adjustable voltage regulator is connected to the power supply terminal, the anode is connected to the ground terminal, and the reference terminal is connected between the first output voltage regulating resistor and the second output voltage regulating resistor; The positive terminals of the first output filter capacitor and the second output filter capacitor are connected to the power supply terminal, and the negative terminals are connected to the ground terminal.

5. The frequency-selective voltage-stabilizing circuit according to claim 1, It is characterized in that The common collector amplifier module includes a triode, a base bias resistor and a collector bias resistor; The base of the transistor is connected to a DC power supply via a base bias resistor; The collector of the triode is connected to a DC power supply via a collector bias resistor; The base of the triode is also connected to the signal input end of the common collector amplifier module; The emitter of the triode serves as the signal output end of the common collector amplifier module.

6. The frequency-selective voltage-stabilizing circuit according to claim 5, It is characterized in that The DC power supply is a constant current source; The input end of the DC power supply is connected to the fire telephone host signal, and the output end outputs DC.

7. The frequency-selective voltage-stabilizing circuit according to claim 5, It is characterized in that The common collector amplifier module also includes a second DC blocking capacitor; The second DC blocking capacitor is arranged between the base of the transistor and the signal input terminal of the common collector amplifier module.

8. The frequency-selective voltage-stabilizing circuit according to claim 1, It is characterized in that It also includes a fire telephone extension demodulation module; The fire telephone extension demodulation module is arranged between the first end of the frequency selection network module and the single chip microcomputer of the fire telephone extension.

9. A fire telephone extension, It is characterized in that It comprises the frequency-selective voltage-stabilizing circuit as claimed in any one of claims 1 to 8.

10. A fire telephone system, It is characterized in that It comprises the fire telephone extension as claimed in claim 9.

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