Ordinary fire alarm detection circuit, ordinary fire automatic alarm controller and ordinary fire automatic alarm system
By employing mutually exclusive conduction control of a two-bus detection loop in a conventional automatic fire alarm system, the problem of the fire alarm detection loop being unable to distinguish between a fire alarm and a line fault was solved, resulting in more accurate detection results and reduced circuit costs.
Patent Information
- Application Number
- CN202520006372.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-02
- Publication Date
- 2025-12-12
- Estimated Expiration
- 2035-01-02
AI Technical Summary
In existing conventional automatic fire alarm systems, the fire alarm detection circuit cannot accurately distinguish between fire alarm outputs and line faults when too many terminals are connected, resulting in inaccurate detection results.
A common type of fire alarm detection circuit is adopted, including a two-bus detection loop. The detection loop enters the fire alarm inspection state or the line inspection state through the mutual exclusion conduction of the first switch unit and the second switch unit, so as to realize the detection of fire alarm output and line fault respectively.
It effectively solves the problem of not being able to distinguish between fire alarms and line faults when too many terminals are connected, improves the accuracy of detection results, and reduces circuit costs by reducing the use of high-cost components.
Smart Images
Figure CN223665074U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model relates to fire alarm detection technical field more specifically, relate to a common type fire alarm detection circuit, common type fire automatic alarm controller and system. BACKGROUND
[0002] Fire automatic alarm system is generally divided into intelligent fire automatic alarm system and common type fire automatic alarm system, and the common type fire automatic alarm system is also traditional type fire automatic alarm system.In the common type fire automatic alarm system, the fire alarm detection loop is the most critical and indispensable part of the whole system, which bears the alarm detection task of all fire alarm detectors in the system.The fire alarm detection loop refers to the detection loop connected with the two buses, which is also commonly known as "zone" circuit, and multiple terminals are mounted on the bus, which can identify the alarm state of the terminal and the line fault state such as open circuit and short circuit.In a common type fire automatic alarm controller, the basic unit element is basically fixed, but the fire alarm detection loop is not, because different fire layout places determine the number of fire alarm detection loops needed.In the existing fire alarm detection loop, the line detection and fire alarm output are both in the same direction, and when the number of terminals increases, the fire alarm current increases, which causes the threshold value to approach the short circuit threshold value and makes it difficult to distinguish between fire alarm output and line fault state, resulting in inaccurate detection results. UTILITY MODEL CONTENTS
[0003] The utility model solves the technical problem in view of the above-mentioned defects of prior art, and provides a common type fire alarm detection circuit, common type fire automatic alarm controller and system.
[0004] The utility model adopts the technical scheme that:
[0005] On the one hand, the utility model provides a common type fire alarm detection circuit, which comprises a two-bus detection loop, the two-bus detection loop comprises a first switch unit, a sampling unit, a fire alarm detector, a second switch unit and a terminal resistor, one end of the first switch unit is connected with a power input end and a control signal input end, the other end of the first switch unit is connected with the sampling unit and one end of the fire alarm detector respectively, the other end of the sampling unit outputs a sampling signal, the other end of the fire alarm detector is connected with one end of the second switch unit, the other end of the second switch unit is connected to the power input end and the control signal input end, the terminal resistor is connected with the fire alarm detector in parallel, and the first switch unit and the second switch unit are mutually exclusive conduction to control the two-bus detection loop to enter the fire alarm inspection state or the line detection state.
[0006] In some embodiments, when the first switch unit is off and the second switch unit is on, the two-bus detection circuit enters a fire alarm inspection state; when the first switch unit is on and the second switch unit is off, the two-bus detection circuit enters a line inspection state.
[0007] In some embodiments, the first switch unit comprises a first triode, a second triode, a first diode, a first resistor, a second resistor, a third resistor and a fourth resistor; an emitter of the first triode is connected with a power input end and one end of the first resistor respectively, the other end of the first resistor is connected with one end of the second resistor, the other end of the second resistor is connected with a collector of the second triode; a base of the second triode is connected with one end of the third resistor, the other end of the third resistor is connected with a control signal input end; an emitter of the second triode is grounded; a base of the first triode is connected between the first resistor and the second resistor; a collector of the first triode is connected with a positive electrode of the first diode, a negative electrode of the first diode is connected with one end of the fourth resistor, the other end of the fourth resistor is connected with the sampling unit.
[0008] In some embodiments, the sampling unit comprises a third triode, a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, a second diode and a third diode; one end of the fifth resistor and a negative electrode of the second diode are both connected with the other end of the fourth resistor, the other end of the fifth resistor and an emitter of the third triode are both grounded; a positive electrode of the second diode is connected with a negative electrode of the third diode and one end of the sixth resistor respectively, a positive electrode of the third diode is connected with the control signal input end, the other end of the sixth resistor is connected with a base of the third triode; a collector of the third triode is connected with one end of the seventh resistor, the other end of the seventh resistor is connected with one end of the eighth resistor, the other end of the eighth resistor is connected with the other end of the fourth resistor and one end of the fire alarm detector respectively.
[0009] In some embodiments, the sampling unit further comprises a first capacitor and a first TVS tube, the first capacitor and the first TVS tube are connected in parallel at one end of the fire alarm detector and connected with a protection ground.
[0010] In some embodiments, the fifth resistor is a sampling resistor; the second diode is a voltage stabilizing diode.
[0011] In some embodiments, the second switch unit comprises a fourth triode, a fifth triode, a sixth triode, a seventh triode, a fuse, a ninth resistor, a tenth resistor, an eleventh resistor, a twelfth resistor, a thirteenth resistor and a fourteenth resistor; the emitter of the fourth triode is connected with one end of the fuse and one end of the ninth resistor respectively, the other end of the fuse is connected with the power input end, the other end of the ninth resistor is connected with one end of the tenth resistor, the other end of the tenth resistor is connected with the collector of the sixth triode, the base of the fourth triode is connected between the ninth resistor and the tenth resistor; the base of the sixth triode is connected with the collector of the seventh triode and one end of the eleventh resistor respectively, one end of the twelfth resistor is connected with the base of the seventh triode, the other end of the twelfth resistor is connected with the control signal input end; the collector of the fourth triode is connected with the collector of the fifth triode and the other end of the fire detector respectively, one end of the thirteenth resistor is connected with the base of the fifth triode, the other end of the thirteenth resistor is connected with the control signal input end; the emitter of the fifth triode is connected with one end of the fourteenth resistor, the other end of the fourteenth resistor and the emitters of the sixth triode and the seventh triode are grounded.
[0012] In some embodiments, the second switch unit further comprises a second capacitor and a second TVS tube, which are connected in parallel with the other end of the fire detector and connected to the protection ground.
[0013] In another aspect, the utility model also provides a common type fire automatic alarm controller, including the common type fire detection circuit of any one above.
[0014] In another aspect, the utility model also provides a common type fire automatic alarm system, including the common type fire automatic alarm controller above.
[0015] The utility model has the advantages that, different from prior art, in the common type fire detection circuit of the utility model, one end of the first switch unit is connected with the power input end and the control signal input end, the other end of the first switch unit is connected with the sampling unit and one end of the fire detector respectively, the other end of the sampling unit outputs the sampling signal, the other end of the fire detector is connected with one end of the second switch unit, the other end of the second switch unit is connected to the power input end and the control signal input end, the terminal resistor is connected in parallel with the fire detector, the first switch unit and the second switch unit are mutually exclusive conduction to control the fire alarm detection circuit to enter the fire patrol inspection state or the line detection state, thereby realizing the detection of the fire output and the line fault respectively, effectively solving the problem that too many terminals are connected and it is unable to distinguish whether it is the fire or the line fault, the detection effect is better, and the detection result is more accurate. BRIEF DESCRIPTION OF DRAWINGS
[0016] Figure 1 is a principle block diagram of the ordinary type fire alarm detection circuit in the embodiment one of the utility model;
[0017] Figure 2 is a circuit layout diagram of the ordinary type fire alarm detection circuit in the embodiment one of the utility model;
[0018] Figure 3 is a work flow chart of the ordinary type fire alarm detection circuit in the embodiment one of the utility model;
[0019] Marked name and serial number in the drawing: first switch unit-1;Sampling unit-2;Fire alarm detector-3;Second switch unit-4;Terminal resistor-5;First switch control module-41;Second switch control module-42. DETAILED DESCRIPTION
[0020] The terms "first", "second", "third", and "fourth" and the like in the description and claims of the utility model and the said drawings are used for distinguishing different objects, and are not used to describe a particular order. In addition, the terms "comprise" and "have" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but can optionally include steps or units not listed, or can optionally include other steps or units inherent to the process, method, product or device.
[0021] In this paper, "embodiment" means that the specific features, structures or characteristics described in conjunction with the embodiment can be included in at least one embodiment of the utility model. The phrase appears at various places in the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment independent of or alternative to other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.
[0022] "Multiple" means two or more. "And / or", which describes the relationship between the associated objects, means that there can be three relationships, for example, A and / or B, which can mean that A exists alone, A and B exist together, and B exists alone. The character " / " generally represents that the associated objects before and after are a "or" relationship.
[0023] Moreover, the terms "up, down, front, back, left, right, upper end, lower end" and the like indicating the direction are all based on the attitude position of the device or equipment described in the scheme in normal use.
[0024] In order to make the purpose, technical scheme and advantages of the embodiments of the utility model clearer, the following will combine the technical scheme in the embodiments of the utility model for clear and complete description, obviously, the described embodiments are part of the embodiments of the utility model, rather than all the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by the person skilled in the art without creative labor belong to the protection scope of the utility model.
[0025] Embodiment one: the utility model embodiment provides a common type fire alarm detection circuit, as shown in Figure 1 The common type fire alarm detection circuit includes two bus detection loops, and the two bus detection loops include a first switch unit 1, a sampling unit 2, a fire alarm detector 3, a second switch unit 4 and a terminal resistor 5; one end of the first switch unit 1 is connected with a power input end and a control signal input end, and the other end of the first switch unit 1 is connected with one end of the sampling unit 2 and the fire alarm detector 3 respectively, the other end of the sampling unit 2 outputs a sampling signal, and the other end of the fire alarm detector 3 is connected with one end of the second switch unit 4; the other end of the second switch unit 4 is connected to the power input end and the control signal input end; the terminal resistor 5 is connected with the fire alarm detector 3 in parallel; the first switch unit 1 and the second switch unit 4 are mutually exclusive conduction to control the two bus detection loops to enter a fire alarm inspection state or a line inspection state.
[0026] Specifically, in the embodiment, the first switch circuit 1 is off, and the second switch circuit 4 is on, the two bus detection loops enter the fire alarm inspection state, and the fire detection circuit in the fire alarm inspection state is as shown by an arrow A. The first switch circuit 1 is on, and the second switch circuit 4 is off, the two bus detection loops enter the line inspection state, and the line inspection circuit in the line inspection state is as shown by an arrow B. Thus, the detection of the fire alarm output and the line fault is realized respectively, the problem that when too many terminals are connected, it is unable to distinguish whether it is a fire alarm or a line fault can be effectively solved, and the detection effect is better.
[0027] The circuit layout of the first switch unit 1 is specifically as shown in Figure 2As shown in FIG. 1, the first switch unit 1 includes a first transistor Q1, a second transistor Q2, a first diode D2, a first resistor R36, a second resistor R39, a third resistor R42 and a fourth resistor R35; the emitter of the first transistor Q1 is connected with a power input terminal and one end of the first resistor R36 respectively, the other end of the first resistor R36 is connected with one end of the second resistor R39, the other end of the second resistor R39 is connected with the collector of the second transistor Q2; one end of the third resistor R42 is connected with the base of the second transistor Q2, the other end of the third resistor R42 is connected with a control signal input terminal; the emitter of the second transistor Q2 is grounded; the base of the first transistor Q1 is connected between the first resistor R36 and the second resistor R39; the collector of the first transistor Q1 is connected with the positive electrode of the first diode D2, the negative electrode of the first diode D2 is connected with one end of the fourth resistor R35, the other end of the fourth resistor R35 is connected with the sampling unit 2.
[0028] As shown in FIG. 2, the circuit layout of the sampling unit 2 is specifically shown in FIG. 3. Figure 2 As shown in FIG. 3, the sampling unit 2 includes a third transistor Q3, a fifth resistor R40, a sixth resistor R43, a seventh resistor R41, an eighth resistor R37, a second diode ZD1 and a third diode D4; one end of the fifth resistor R40 and the negative electrode of the second diode ZD1 are both connected with the other end of the fourth resistor R35, the other end of the fifth resistor R40 and the emitter of the third transistor Q3 are both grounded; the positive electrode of the second diode ZD1 is connected with the negative electrode of the third diode D4 and one end of the sixth resistor R43 respectively, the positive electrode of the third diode D4 is connected with a control signal input terminal, the other end of the sixth resistor R43 is connected with the base of the third transistor Q3; the collector of the third transistor Q3 is connected with one end of the seventh resistor R41, the other end of the seventh resistor R41 is connected with one end of the eighth resistor R37, the other end of the eighth resistor R37 is connected with the other end of the fourth resistor R35 and one end of the fire detector 3 respectively. Specifically, the fifth resistor R40 is a sampling resistor, the resistance value of the sampling resistor is 750Ω. The second diode ZD1 is a voltage stabilizing diode.
[0029] Under normal circumstances, the fire detection circuit belongs to an external output unit, and port protection and line protection are considered during design. The existing fire detection circuit not only uses high-cost devices such as voltage-dependent resistors and gas discharge tubes in the external port part, but also has a series of short-circuit protection units, which further increases the cost. In particular, in the identification of short-circuit, open-circuit and fire, the scheme adopted is to use a comparator to distinguish the state, and the cost of the comparator is relatively high. For a single fire detection circuit, the cost difference may not be obvious, but when more fire detection circuits are needed, the cost difference will become more significant.
[0030] Therefore, further, the sampling unit 2 further comprises a first capacitor C21 and a first transient voltage suppression diode TVS1, which are connected in parallel at one end of the fire detector 3 and connected to the protection ground. In this embodiment, bulky and high-cost devices such as a voltage-dependent resistor and a discharge tube are removed at the port, and a small-volume and low-cost first capacitor C21 and a first transient voltage suppression diode TVS1 are used instead. By using a transient voltage suppression diode, the interference level is filtered, so as to achieve the EMC performance of equivalent effect by using few protective devices, thereby effectively reducing the design and manufacturing cost.
[0031] The circuit layout of the second switch unit 4 is specifically shown in Figure 2 The second switch unit 4 comprises a fourth transistor Q4, a fifth transistor Q5, a sixth transistor Q6, a seventh transistor Q7, a fuse F2, a ninth resistor R46, a tenth resistor R47, an eleventh resistor R48, a twelfth resistor R53, a thirteenth resistor R49, and a fourteenth resistor R51. The emitter of the fourth transistor Q4 is connected to one end of the fuse F2 and one end of the ninth resistor R46, the other end of the fuse F2 is connected to the power input end, the other end of the ninth resistor R46 is connected to one end of the tenth resistor R47, the other end of the tenth resistor R47 is connected to the collector of the sixth transistor Q6, and the base of the fourth transistor Q4 is connected between the ninth resistor R46 and the tenth resistor R47. The base of the sixth transistor Q6 is connected to the collector of the seventh transistor Q7 and one end of the eleventh resistor R48, the base of the seventh transistor Q7 is connected to one end of the twelfth resistor R53, and the other end of the twelfth resistor R53 is connected to the control signal input end. The collector of the fourth transistor Q4 is connected to the collector of the fifth transistor Q5 and the other end of the fire detector 3, the base of the fifth transistor Q5 is connected to one end of the thirteenth resistor R49, and the other end of the thirteenth resistor R49 is connected to the control signal input end. The emitter of the fifth transistor Q5 is connected to one end of the fourteenth resistor R51, the other end of the fourteenth resistor R51 and the emitters of the sixth transistor Q6 and the seventh transistor Q7 are grounded.
[0032] The fourth transistor Q4, the sixth transistor Q6, the seventh transistor Q7, the fuse F2, the ninth resistor R46, the tenth resistor R47, the eleventh resistor R48, and the twelfth resistor R53 constitute a first switch control module 41 in the second switch unit 4, for realizing the power input and the control signal input. The fifth transistor Q5, the thirteenth resistor R49, and the fourteenth resistor R51 constitute a second switch control module 42 in the second switch unit 4, for realizing the control signal input and forming a line detection backflow path in the line detection state.
[0033] Furthermore, the second switching unit 4 also includes a second capacitor C25 and a second transient voltage regulator diode (TVS2). The second capacitor C25 and the second TVS2 are connected in parallel to the other end of the fire detector 3 and connected to the protective ground. This uses the small, low-cost second capacitor C25 and the second TVS2 instead of large, high-cost components such as varistors and discharge tubes. By reducing the number of components used in the circuit, the overall component cost of the circuit is reduced. Moreover, the smaller size of each component used in this embodiment allows for a smaller circuit board, effectively reducing the design and manufacturing cost of the circuit board.
[0034] In this embodiment, the terminating resistor 5 is a diode, which needs to be connected between the positive and negative terminals of the two buses, as shown in the attached figure. Figure 1 As shown. When diodes are used appropriately as resistors, they can provide greater flexibility and choice in circuit design.
[0035] The following section, based on the circuit layout of the aforementioned ordinary fire alarm detection circuit, explains the principle of achieving fire alarm output and line fault detection in its specific implementation:
[0036] In this embodiment, fire alarm output and line fault detection are time-division multiplexed. A complete work cycle is divided into fire alarm inspection state and line inspection state. For the specific workflow, please refer to [link to documentation]. Figure 3 .pass Figure 2 The ZONE-_CTRL signal shown enables the mutual exclusion conduction of the first transistor Q1 and the fourth transistor Q4, thereby distinguishing between the fire alarm inspection state and the line detection state. Specifically, when ZONE-_CTRL is low, the fourth transistor Q4 is turned on, and the first transistor Q1 is turned off, entering the fire alarm inspection state; when ZONE-_CTRL is high, the fourth transistor Q4 is turned off, and the first transistor Q1 is turned on, entering the line detection state.
[0037] The fire alarm judgment logic is as follows:
[0038] In fire alarm inspection mode, because transistor Q4 is turned on, the 24V voltage flows through transistor Q4, then through the terminal, and back to system ground via the sampling resistor. If the terminal does not report a fire alarm, the current draw is small, resulting in a low voltage across the sampling resistor, meaning a low sampled value. Conversely, when the terminal alarms, the current draw is large, resulting in a high voltage across the sampling resistor. Once the voltage reaches the corresponding threshold, a fire alarm is considered to have occurred. It is understood that the terminal here refers to fire detector 3.
[0039] The fault diagnosis logic is as follows:
[0040] In the line detection state, since the first triode Q1 is turned on and the fifth triode Q5 is turned on, the 24V voltage passes through the first triode Q1 and then returns to the system ground through the parallel path of the first diode D2, the fifth triode Q5 and the sampling resistor. If there is no short circuit in the external line at this time, the sampling value is the sum of the turn-on voltage drop of the fifth triode Q5 and the turn-on voltage drop of the terminal resistor 5, if the external line is short-circuited at this time, the sampling value is the turn-on voltage drop of the fifth triode Q5, and if the external line is open at this time, the sampling value is the voltage division value of the fourth resistor R35 and the sampling resistor to 24V. According to the different thresholds, different fault states can be distinguished.
[0041] The embodiment has obvious advantages in the protection of short circuit in the unit scheme. Without additional short circuit protection units, the purpose of not damaging the device in the short circuit can be achieved. Whether in the line detection process or in the fire alarm output process, the unit will not be damaged. The reason is that in the line detection stage, the line detection current is limited by the fourth resistor R35, and whether the short circuit exists, the maximum output current is only several mA to ten mA, and the current level is very small. For the fire alarm output stage, whether the short circuit exists, the maximum output current is only several tens of mA, so the cost of the short circuit protection part can be reduced.
[0042] Embodiment two: the utility model embodiment further provides a common type fire automatic alarm controller, including the common type fire alarm detection circuit provided in the above embodiment one. The cost of the common type fire alarm detection circuit is reduced, so that the manufacturing cost of the common type fire automatic alarm controller can also be reduced, which helps to improve its market competitiveness. For the description of the common type fire alarm detection circuit, please refer to embodiment one.
[0043] Embodiment three: the utility model embodiment further provides a common type fire automatic alarm system, including the common type fire automatic alarm controller provided in embodiment two. The structure and type of the common type fire automatic alarm controller should be based on the actual application, and the embodiment is not limited.
[0044] It should be understood that those skilled in the art can improve or change according to the above description, and all these improvements and changes should belong to the protection scope of the appended claims of the utility model.
Claims
1. A general-purpose fire alarm detection circuit, comprising a two-wire detection loop, characterized in that: The dual-bus detection loop includes a first switching unit, a sampling unit, a fire alarm detector, a second switching unit, and a terminating resistor. One end of the first switching unit is connected to a power input terminal and a control signal input terminal. The other end of the first switching unit is connected to one end of the sampling unit and one end of the fire alarm detector, respectively. The other end of the sampling unit outputs a sampling signal. The other end of the fire alarm detector is connected to one end of the second switching unit. The other end of the second switching unit is connected to both the power input terminal and the control signal input terminal. The terminating resistor is connected in parallel with the fire alarm detector. The first switching unit and the second switching unit are mutually exclusive to control the dual-bus detection loop to enter the fire alarm inspection state or the line detection state.
2. The ordinary fire alarm detection circuit according to claim 1, characterized in that: When the first switch unit is turned off, the second switch unit is turned on, and the two-bus detection circuit enters the fire alarm inspection state; when the first switch unit is turned on, the second switch unit is turned off, and the two-bus detection circuit enters the line detection state.
3. The ordinary fire alarm detection circuit according to claim 1, characterized in that: The first switching unit includes a first transistor, a second transistor, a first diode, a first resistor, a second resistor, a third resistor, and a fourth resistor. The emitter of the first transistor is connected to the power input terminal and one end of the first resistor, the other end of the first resistor is connected to one end of the second resistor, and the other end of the second resistor is connected to the collector of the second transistor. The base of the second transistor is connected to one end of the third resistor, and the other end of the third resistor is connected to the control signal input terminal. The emitter of the second transistor is grounded. The base of the first transistor is connected between the first resistor and the second resistor. The collector of the first transistor is connected to the anode of the first diode, the cathode of the first diode is connected to one end of the fourth resistor, and the other end of the fourth resistor is connected to the sampling unit.
4. The ordinary fire alarm detection circuit according to claim 3, characterized in that: The sampling unit includes a third transistor, a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, a second diode, and a third diode. One end of the fifth resistor and the cathode of the second diode are both connected to the other end of the fourth resistor. The other end of the fifth resistor and the emitter of the third transistor are both grounded. The anode of the second diode is connected to the cathode of the third diode and one end of the sixth resistor. The anode of the third diode is connected to the control signal input terminal. The other end of the sixth resistor is connected to the base of the third transistor. The collector of the third transistor is connected to one end of the seventh resistor. The other end of the seventh resistor is connected to one end of the eighth resistor. The other end of the eighth resistor is connected to the other end of the fourth resistor and one end of the fire detector.
5. The ordinary fire alarm detection circuit according to claim 4, characterized in that: The sampling unit further includes a first capacitor and a first TVS diode, which are connected in parallel at one end of the fire detector and connected to the protective ground.
6. The ordinary fire alarm detection circuit according to claim 4 or 5, characterized in that: The fifth resistor is a sampling resistor; the second diode is a Zener diode.
7. The ordinary fire alarm detection circuit according to claim 1, characterized in that: The second switching unit includes a fourth transistor, a fifth transistor, a sixth transistor, a seventh transistor, a fuse, a ninth resistor, a tenth resistor, an eleventh resistor, a twelfth resistor, a thirteenth resistor, and a fourteenth resistor. The emitter of the fourth transistor is connected to one end of the fuse and one end of the ninth resistor. The other end of the fuse is connected to the power input terminal. The other end of the ninth resistor is connected to one end of the tenth resistor. The other end of the tenth resistor is connected to the collector of the sixth transistor. The base of the fourth transistor is connected between the ninth and tenth resistors. The base of the sixth transistor is... The fourth transistor is connected to the collector of the eleventh resistor and the seventh transistor. The base of the seventh transistor is connected to one end of the twelfth resistor, and the other end of the twelfth resistor is connected to the control signal input terminal. The collector of the fourth transistor is connected to the collector of the fifth transistor and the other end of the fire detector. The base of the fifth transistor is connected to one end of the thirteenth resistor, and the other end of the thirteenth resistor is connected to the control signal input terminal. The emitter of the fifth transistor is connected to one end of the fourteenth resistor, and the other end of the fourteenth resistor, as well as the emitters of the sixth and seventh transistors, are all grounded.
8. The ordinary fire alarm detection circuit according to claim 7, characterized in that: The second switching unit also includes a second capacitor and a second TVS diode, which are connected in parallel at the other end of the fire detector and connected to the protective ground.
9. A common type of automatic fire alarm controller, characterized in that: Includes the conventional fire alarm detection circuit as described in any one of claims 1-8.
10. A common type of automatic fire alarm system, characterized in that: Includes the ordinary type automatic fire alarm controller as described in claim 9.