Rear-phase-cut single-live-wire type wall light modulator

Abstract

The invention provides a rear-phase-cut single-live-wire type wall light modulator. The rear-phase-cut single-live-wire type wall light modulator comprises an MOS tube switch loop unit, a single-chip microcomputer control unit and a direct-current power supply unit. Wherein the direct current power supply unit comprises an alternating current voltage waveform acquisition circuit, a direct current voltage drop circuit, an overcurrent protection circuit and a filtering voltage stabilizing circuit. The single-chip microcomputer control unit comprises a single-chip microcomputer, a potentiometer, a triode Q6, a triode Q5 and a triode Q7, the PC2 end of the single-chip microcomputer is connected with the potentiometer, when the resistance value of the potentiometer changes, the voltage collected by the PC2 end changes, and the PA6 end of the single-chip microcomputer outputs different voltage signals to control the on-off of the triode Q6, the triode Q5 and the triode Q7 so as to adjust the on-off time of the MOS tube; the output end of the alternating current voltage waveform acquisition circuit is connected with a PC1 port of the single chip microcomputer to provide a phase reference; after alternating current passes through the direct current power supply unit, 5V direct current is output and is connected with a VDD end of the single chip microcomputer to supply power to the single chip microcomputer; the light modulator can stably modulate light at low brightness.

Description

Technical Field

[0001] The invention relates to a dimming product fixedly installed in a wall junction box, in particular to a rear-cut single-fire wall dimmer. Background Art

[0002] A dimmer is a device used to adjust the brightness of lighting equipment, which can meet the lighting needs in different scenarios. Dimmers are widely used in various places such as homes, offices, and commercial buildings, providing a comfortable and adjustable lighting environment. The dimmers currently on the market generally use thyristors as switching devices, and the dimming circuit is relatively simple. However, since thyristor dimming controls the brightness of LEDs by changing the leading edge of the voltage waveform, light jitter or flicker may occur at low brightness.

[0003] Therefore, there is an urgent need for a dimmer with a simple structure, high compatibility, and stable dimming at low brightness. Summary of the invention

[0004] In order to solve the above problems, the purpose of the present invention is to provide a rear-cut single-fire wall dimmer, whose external dimensions are designed according to the space of the junction box, and uses MOS tubes instead of thyristors as switching devices. Since MOS tube dimming controls the LED brightness by changing the trailing edge of the voltage waveform, there will be no light jitter or flickering under low brightness conditions. The dimmer greatly improves the compatibility with lamps, effectively solves the problem of light jitter and flickering under low brightness conditions, and improves the compatibility with lamps.

[0005] To achieve the above object, the present invention provides a rear-cut single-fire wall dimmer, comprising a MOS tube switch circuit unit, a single-chip control unit and a DC power supply unit, wherein:

[0006] The MOS tube switch circuit unit comprises:

[0007] The terminal J2 connected to the live wire of the power supply is connected to the drain of the MOS tube Q1. The gate of the MOS tube Q1 is connected to the resistor R7, the resistor R8, the resistor R9, and the resistor R10 which are connected in series in sequence and then connected to the gate of the MOS tube Q2. The drain of the MOS tube Q2 is connected to the anode of the diode D2, and the cathode of the diode D2 is connected to the cathode of the diode D1.

[0008] A single-pole double-throw switch, whose fixed end contact is connected to the drain of the MOS tube Q2, the first moving end contact of the single-pole double-throw switch is connected to the wiring terminal J1, and the second moving end contact of the single-pole double-throw switch is connected to the wiring terminal J3, so that the single-pole double-throw switch is selectively connected to the wiring terminal J1 or the wiring terminal J3.

[0009] The single chip microcomputer control unit comprises:

[0010] A single-chip microcomputer, whose VDD terminal is the single-chip microcomputer power supply terminal, connected to the output terminal of the DC power supply unit; the PC1 terminal of the single-chip microcomputer is the AC signal acquisition terminal; the PC2 terminal of the single-chip microcomputer is the voltage signal acquisition terminal; the PA6 terminal of the single-chip microcomputer is the voltage signal output terminal;

[0011] The straight-slide potentiometer changes its resistance value by sliding the dimming handle, and the resistor R17 is connected in series with the straight-slide potentiometer and then connected to the PC2 terminal of the single-chip computer; the rotary potentiometer changes its resistance value by rotating the adjustment dial; the resistor R19, the straight-slide potentiometer and the rotary potentiometer are connected in series in sequence between the output terminal of the DC power supply unit and the ground;

[0012] Transistor Q6, transistor Q5 and transistor Q7, wherein the collector of transistor Q6 is connected to resistor R11 and then to the anode of diode D6, the cathode of D6 is connected to resistor R12 and then to the base of transistor Q6; the base of transistor Q6 is connected to the base of transistor Q5 and then to the collector of transistor Q7, the base of transistor Q7 is connected in series with resistor R15 and then to the PA6 terminal of single chip computer; a wiring is drawn out between the emitter of transistor Q6 and the emitter of transistor Q5 and connected to between resistor R8 and resistor R9, so that the MOS tube switch loop unit is connected to the single chip computer control unit.

[0013] The DC power supply unit includes: an AC voltage waveform acquisition circuit, a DC voltage drop circuit, an overcurrent protection circuit and a filtering and voltage stabilizing circuit, wherein:

[0014] The AC voltage waveform acquisition circuit includes: a diode D1 connected to the wiring terminal J2, a resistor R13, a resistor R18 and a resistor 14 connected in series from the cathode of the diode D1, and then grounded; a wiring drawn between the resistor R18 and the resistor R14 is connected to the PC1 terminal of the single chip computer to acquire the AC voltage waveform;

[0015] The DC voltage drop circuit comprises: a transistor Q3, wherein a resistor R1, a resistor R2 and a resistor R3 are connected in series between the collector and the base of the transistor Q3 in sequence; the cathode of the three-terminal voltage regulator is connected to the base of the transistor Q3;

[0016] The overcurrent protection circuit comprises: the emitter of the transistor Q4 is connected in series with the resistor R5 and the resistor R6 in sequence and then grounded; the wiring drawn between the resistor R5 and the resistor R6 is connected to the reference electrode of the three-terminal regulator;

[0017] The filtering and voltage stabilizing circuit comprises: a low voltage difference linear voltage regulator, wherein capacitors C6 and C7 are connected in parallel between the input end and the ground end of the low voltage difference linear voltage regulator, and capacitor C8 is connected in parallel between the output end and the ground end of the low voltage difference linear voltage regulator; wherein the input end of the low voltage difference linear voltage regulator is connected to the emitter of the transistor Q4;

[0018] In one embodiment of the present invention, the MOS transistor switch circuit unit further includes: a wiring lead between the resistor R7 and the gate of the MOS transistor Q1 is connected to the anode of the diode D4, and a cathode of the diode D4 is connected to a wiring lead between the resistor R7 and the resistor R8; a wiring lead between the resistor R10 and the gate of the MOS transistor Q2 is connected to the anode of the diode D3, and a cathode of the diode D3 is connected to a wiring lead between the resistor R9 and the resistor R10; a source of the MOS transistor Q1 and a source of the MOS transistor Q2 are both grounded;

[0019] In one embodiment of the present invention, the single chip control unit further includes: the adjusting disk of the rotary potentiometer is connected to the resistor of the rotary potentiometer through a connecting rod, and capacitors C3 and C4 are connected in parallel between the variable resistance end of the direct sliding potentiometer and the variable resistance end of the rotary potentiometer.

[0020] In one embodiment of the present invention, the single chip control unit further comprises: the emitter of the transistor Q6 is connected to the emitter of the transistor Q5; the collector of the transistor Q5 and the emitter of the transistor Q7 are both grounded;

[0021] In an embodiment of the present invention, the AC voltage waveform acquisition circuit further includes: a capacitor C5 and a voltage stabilizing diode D5 are connected in parallel at both ends of the resistor R14.

[0022] In one embodiment of the present invention, the DC voltage drop circuit further comprises: the emitter of the transistor Q3 is connected to the base of the transistor Q4; the anode of the three-terminal voltage regulator is grounded;

[0023] In an embodiment of the present invention, the overcurrent protection circuit further includes: a resistor R4 connected between the base and the emitter of the transistor Q4.

[0024] In an embodiment of the present invention, the filtering and voltage stabilizing circuit further includes: a ground terminal of the low voltage difference linear regulator is grounded.

[0025] Compared with the existing dimmers, the rear-cut single-fire wall dimmer provided by the present invention uses a MOS tube as a switching device, so the output power can be controlled by adjusting the conduction angle of the MOS tube to change the intensity of the light, thereby effectively solving the problem of light flickering at low brightness. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0027] Figure 1 FIG. 4 is a circuit diagram of an embodiment of the present invention.

[0028] Figure 2 FIG. 4 is a circuit diagram of a MOS switch loop unit in an embodiment of the present invention.

[0029] Figure 3 The present invention is a circuit diagram of a single chip microcomputer control unit according to an embodiment of the present invention.

[0030] Figure 4 This is a circuit diagram of a DC power supply unit according to an embodiment of the present invention. DETAILED DESCRIPTION

[0031] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] Figure 1 FIG. 1 is a circuit diagram of an embodiment of the present invention. Figure 1 As shown, this embodiment provides a rear-cut single-fire wall dimmer, which includes a MOS tube switch circuit unit, a DC power supply unit, and a single-chip control unit. The dimmer of this embodiment is used as a unit dimming switch, wherein:

[0033] Figure 2 FIG. 1 is a circuit diagram of a MOS switch loop unit in an embodiment of the present invention. Figure 2 As shown, the MOS transistor switch circuit unit includes: a terminal J2 connected to the live wire of the power supply, the terminal J2 is connected to the drain (pin 2) of the MOS transistor Q1, the gate (pin 1) of the MOS transistor Q1 is connected to the gate (pin 1) of the MOS transistor Q2 after being connected in series with resistors R7, R8, R9, and R10 in sequence, the drain (pin 2) of the MOS transistor Q2 is connected to the anode of the diode D2, and the cathode of the diode D2 is connected to the cathode of the diode D1; the source (pin 3) of the MOS transistor Q1 and the source (pin 3) of the MOS transistor Q2 are both grounded; a wiring is drawn between the resistor R7 and the gate (pin 1) of the MOS transistor Q1 and connected to the anode of the diode D4, and the cathode of the diode D4 is connected to the wiring drawn between the resistor R7 and the resistor R8; a wiring is drawn between the resistor R10 and the gate (pin 1) of the MOS transistor Q2 and connected to the anode of the diode D3, and the cathode of the diode D3 is connected to the wiring drawn between the resistor R9 and the resistor R10;

[0034] The fixed end contact 2 of the single-pole double-throw switch S1 is connected to the drain (pin 2) of the MOS tube Q2, the terminal J1 is connected to the moving end contact 1 (first moving end contact) of the single-pole double-throw switch S1, and the terminal J3 is connected to the moving end contact 3 (second moving end contact) of the single-pole double-throw switch S1, so that the single-pole double-throw switch S1 is selectively connected to the terminal J1 or the terminal J3; when the dimmer is used as a unit dimming switch, the live wire of the lamp can be selectively connected to the terminal J1 or the terminal J3, and the corresponding single-pole double-throw switch S1 should also be connected to the corresponding moving end contact 1 or the moving end contact 3 to achieve the purpose of connecting the dimmer to the lamp;

[0035] When the voltage flowing through the terminal J2 is a positive voltage, the MOS tube Q1 and the MOS tube Q2 are controlled to be turned on at the same time, and the current flows from the MOS tube Q1 turned on in the positive half cycle through the built-in forward diode of the MOS tube Q2 to the terminal J1 or the terminal J3; when the voltage flowing through the terminal J2 is a negative voltage, the current flows from the MOS tube Q2 turned on in the negative half cycle through the built-in reverse diode of the MOS tube Q1 to the terminal J2;

[0036] Figure 3 FIG. 1 is a circuit diagram of a single chip microcomputer control unit according to an embodiment of the present invention. Figure 3 As shown, the single-chip control unit circuit includes: a single-chip U1, which has 8 pins in total, the 1-pin VDD terminal of the single-chip U1 is the power supply terminal of the single-chip U1, and the output of the DC power supply unit is connected to the pin; the 5-pin PC1 terminal of the single-chip U1 is the AC signal acquisition terminal; the 4-pin PC2 terminal of the single-chip U1 is the voltage signal acquisition terminal, and the 2-pin PA6 terminal of the single-chip U1 is the voltage signal output terminal;

[0037] The resistor R19, the straight-slide potentiometer VR1 and the rotary potentiometer VR2 are connected in series between the output voltage of the DC power supply unit and the ground. The straight-slide potentiometer VR1 can change its resistance value by sliding the dimming handle. The straight-slide potentiometer VR1 is connected in series with the resistor R17 and then connected to the 4-pin PC2 terminal of the single-chip computer U1. When the resistance value of the potentiometer changes, the 2-pin PA6 terminal of the single-chip computer can output different voltage signals. The adjustment disk of the rotary potentiometer VR2 is connected to the resistor body of the rotary potentiometer through a connecting rod. Turning the adjustment disk can change the resistance value of the rotary potentiometer. Capacitors C3 and C4 are connected in parallel between the variable resistance end of the straight-slide potentiometer and the variable resistance end of the rotary potentiometer.

[0038] Transistor Q6, transistor Q5 and transistor Q7, the collector (pin 2) of transistor Q6 is connected to resistor R11 and then to the anode of diode D6, the cathode of D6 is connected to resistor R12 and then to the base (pin 1) of transistor Q6; the base (pin 1) of transistor Q6 is connected to the base (pin 1) of transistor Q5 and then to the collector (pin 2) of transistor Q7, the base (pin 1) of transistor Q7 is connected in series with resistor R15 and then to the 2-pin PA6 terminal of single-chip computer U1; a wiring is drawn between the emitter (pin 3) of transistor Q6 and the emitter (pin 3) of transistor Q5 and connected to resistor R8 and resistor R9, so that the MOS tube switch loop unit is connected to the single-chip computer control unit; the emitter (pin 3) of transistor Q6 is connected to the emitter (pin 3) of transistor Q5; the collector (pin 2) of transistor Q5 and the emitter (pin 3) of transistor Q7 are both grounded.

[0039] Figure 4 FIG. 1 is a circuit diagram of a DC power supply unit according to an embodiment of the present invention. Figure 4 As shown, the DC power supply unit includes: an AC voltage waveform acquisition circuit, a DC voltage drop circuit, an overcurrent protection circuit and a filtering and voltage stabilizing circuit, wherein:

[0040] The AC voltage waveform acquisition circuit includes: a diode D1 connected to the terminal J2, and then connected in series with resistors R13, R18, and 14 and then grounded, and a wiring is drawn between the resistors R18 and R14 and connected to the 5-pin PC1 of the single-chip computer U1 to collect the AC voltage waveform as a phase reference for the signal output of the single-chip computer U1, and a capacitor C5 and a voltage stabilizing diode D5 are connected in parallel at both ends of the resistor R14;

[0041] The DC voltage drop circuit includes: a transistor Q3, a resistor R1, a resistor R2 and a resistor R3 are connected in series between the collector (pin 2) and the base (pin 1) of the transistor Q3, and the emitter (pin 3) of the transistor Q3 is connected to the base (pin 1) of the transistor Q4; the cathode (pin 3) of the three-terminal voltage regulator T1 is connected to the base (pin 1) of the transistor Q3, and the anode (pin 2) of the three-terminal voltage regulator T1 is grounded. The live AC power of the power supply outputs a 10V DC voltage after passing through the DC voltage drop circuit, which is connected to the anode of the diode D6 and R11 to supply power to the MOS tube switch loop unit.

[0042] The overcurrent protection circuit comprises: a transistor Q4, whose emitter (pin 3) is connected in series with a resistor R5 and a resistor R6 in sequence and then grounded; a wiring is drawn between the resistor R5 and the resistor R6 and connected to the reference electrode (pin 1) of the three-terminal regulator T1, the resistor R4 is connected between the base (pin 1) and the emitter (pin 3) of the transistor Q4, and the base (pin 1) of the transistor Q4 is connected to the emitter (pin 3) of the transistor Q3;

[0043] The filtering and voltage stabilizing circuit comprises: a low-voltage difference linear voltage regulator V1, wherein capacitors C6 and C7 are connected in parallel between the input end (pin 2) of the low-voltage difference linear voltage regulator V1 and the ground end (pin 1) of the low-voltage difference linear voltage regulator V1, capacitor C8 is connected in parallel between the output end (pin 3) of the low-voltage difference linear voltage regulator V1 and the ground end (pin 1) of the low-voltage difference linear voltage regulator V1, and the ground end (pin 1) of the low-voltage difference linear voltage regulator V1 is connected to the ground; wherein, the input end (pin 2) of the low-voltage difference linear voltage regulator V1 is connected to the emitter (pin 3) of the transistor Q4; the 10V DC voltage is reduced to 5V DC after passing through the low-voltage difference linear voltage regulator V1, and the 5V DC is passed through a resistor R19, a direct-slide potentiometer VR1 and a rotary potentiometer VR2 to provide a reference voltage for the PC2 end of the single-chip computer U1.

[0044] Among them, the current input from the live wire end of the power supply passes through the positively connected diode D1 and then flows through the resistor R3 and the resistor R2 in sequence to the base of the transistor Q3 (pin 1). The transistor Q3 is turned on, and the current flows through the emitter of the transistor Q3 (pin 3) and then flows into the base of the transistor Q4 (pin 1). The transistor Q4 is turned on, and the current passes through the emitter of the transistor Q4 (pin 3) to the input end of the low-voltage difference linear regulator V1. The output end of the low-voltage difference linear regulator V1 is connected to the 1-pin VDD of the single-chip computer U1;

[0045] In order to better understand the dimmer of the present invention, the working principle of the dimmer is described as follows:

[0046] When the dimmer is used as a unit dimming switch, the customer moves the dimming handle according to the needs, and the voltage at the 4-pin PC2 terminal of the microcontroller U1 changes according to the resistance changes of the straight-slide potentiometer VR1 and the rotary potentiometer VR2, and the 2-pin PA6 terminal of the microcontroller U1 outputs different voltage signals. When the voltage signal is at a low level, transistor Q7 is turned off, transistor Q5 is turned off, the 10V DC voltage is connected to the base of transistor Q6 (pin 1) through a resistor R12 in series after the diode D6 is connected in a positive direction, Q6 is turned on, and the current of the emitter of transistor Q6 (pin 3) controls the MOS tube Q2 to be turned on through resistors R9 and R10, and controls the MOS tube Q1 to be turned on through resistors R8 and R7; the width of the low level is different, the time when the transistor Q7 is turned off is different, that is, the turn-on time of the MOS tube Q1 and the MOS tube Q2 is different; the longer the turn-on time of the MOS tube Q1 and the MOS tube Q2 in a voltage cycle, the greater the current, that is, the higher the brightness of the load lamp, and the brightness of the lamp can be changed by changing the width of the low level emitted by the 2-pin PA6 end of the single-chip microcomputer U1 to achieve the purpose of dimming.

[0047] In another embodiment of the present invention, the dimmer can also be used as a three-position dimmer switch. When the dimmer is used as a three-position dimmer switch, it is also required to be used in conjunction with an ordinary three-position switch, and the terminal J1 and the terminal J3 are respectively connected to two discrete terminals of the three-position ordinary switch; at this time, the working principle of the dimmer is the same as when the dimmer is used as a single-position dimmer switch.

[0048] Those skilled in the art can understand that the accompanying drawings are only schematic diagrams of an embodiment, and the modules or processes in the accompanying drawings are not necessarily required to implement the present invention.

[0049] Those skilled in the art can understand that the modules in the device in the embodiment can be distributed in the device in the embodiment according to the description of the embodiment, or can be changed accordingly and located in one or more devices different from the embodiment. The modules in the above embodiment can be combined into one module, or can be further divided into multiple sub-modules.

[0050] Finally, it should be noted that 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 they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. 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 rear-cut single-fire wall dimmer, characterized in that: It includes a MOS tube switch circuit unit, a DC power supply unit and a single-chip microcomputer control unit, wherein: The MOS tube switch circuit unit comprises: A terminal J2 connected to the live wire of the power supply, the terminal J2 is connected to the drain of the MOS tube Q1, the gate of the MOS tube Q1 is connected to the gate of the MOS tube Q2 after being connected in series with resistors R7, R8, R9 and R10, the drain of the MOS tube Q2 is connected to the anode of the diode D2, and the cathode of the diode D2 is connected to the cathode of the diode D1; A single-pole double-throw switch, whose fixed end contact is connected to the drain of the MOS tube Q2, the first movable end contact of the single-pole double-throw switch is connected to the wiring terminal J1, and the second movable end contact of the single-pole double-throw switch is connected to the wiring terminal J3, so that the single-pole double-throw switch is selectively connected to the wiring terminal J1 or the wiring terminal J3; The single chip microcomputer control unit comprises: A single-chip microcomputer, whose VDD terminal is the power supply terminal of the single-chip microcomputer and is connected to the output terminal of the DC power supply unit; the PC1 terminal of the single-chip microcomputer is the AC voltage waveform acquisition terminal; the PC2 terminal of the single-chip microcomputer is the voltage conversion signal acquisition terminal; the PA6 terminal of the single-chip microcomputer is the voltage signal output terminal; A straight-slide potentiometer and a rotary potentiometer, wherein the straight-slide potentiometer changes its resistance value by sliding the dimming handle, the straight-slide potentiometer is connected in series with a resistor R17 and then connected to the PC2 terminal of the single-chip computer, and the rotary potentiometer changes its resistance value by rotating the adjustment dial. Resistor R19, the straight-slide potentiometer and the rotary potentiometer are connected in series in sequence between the output terminal of the DC power supply unit and the ground; Transistor Q6, transistor Q5 and transistor Q7, wherein the collector of the transistor Q6 is connected to the resistor R11 and then to the anode of the diode D6, the cathode of D6 is connected to the resistor R12 and then to the base of the transistor Q6; the base of the transistor Q6 is connected to the base of the transistor Q5 and then to the collector of the transistor Q7, the base of the transistor Q7 is connected in series with the resistor R15 and then to the PA6 terminal of the single chip computer, and a wiring is drawn between the emitter of the transistor Q6 and the emitter of the transistor Q5 and connected between the resistor R8 and the resistor R9; The DC power supply unit includes: an AC voltage waveform acquisition circuit, a DC voltage drop circuit, an overcurrent protection circuit and a filtering and voltage stabilizing circuit.

2. The rear-cut single-fire wall dimmer according to claim 1, characterized in that: The AC voltage waveform acquisition circuit includes: a diode D1 connected to the wiring terminal J2, a resistor R13, a resistor R18 and a resistor 14 connected in series from the cathode of the diode D1, and then grounded; a wiring drawn between the resistor R18 and the resistor R14 is connected to the PC1 terminal of the single chip computer; The DC voltage drop circuit comprises: a transistor Q3, with resistors R1, R2 and R3 connected in series between its collector and base; a three-terminal voltage regulator, with its cathode connected to the base of the transistor Q3; The overcurrent protection circuit comprises: a transistor Q4, the emitter of which is connected in series with a resistor R5 and a resistor R6 and then grounded; a wiring drawn between the resistor R5 and the resistor R6 is connected to a reference electrode of the three-terminal regulator; The filtering and voltage stabilizing circuit includes: a low voltage difference linear regulator, wherein capacitors C6 and C7 are connected in parallel between the input end and the ground end of the low voltage difference linear regulator, and capacitor C8 is connected in parallel between the output end and the ground end of the low voltage difference linear regulator; wherein the input end of the low voltage difference linear regulator is connected to the emitter of the transistor Q4.

3. The rear-cut single-fire wall dimmer according to claim 1, characterized in that: The wiring led out between the resistor R7 and the gate of the MOS tube Q1 is connected to the anode of the diode D4, and the cathode of the diode D4 is connected to the wiring led out between the resistor R7 and the resistor R8; the wiring led out between the resistor R10 and the gate of the MOS tube Q2 is connected to the anode of the diode D3, and the cathode of the diode D3 is connected to the wiring led out between the resistor R9 and the resistor R10; the source of the MOS tube Q1 and the source of the MOS tube Q2 are both grounded.

4. The rear-cut single-fire wall dimmer according to claim 1, characterized in that: The adjusting disk of the rotary potentiometer is connected to the resistor of the rotary potentiometer through a connecting rod, and capacitors C3 and C4 are connected in parallel between the variable resistance end of the direct-slide potentiometer and the variable resistance end of the rotary potentiometer.

5. The rear-cut single-fire wall dimmer according to claim 1, characterized in that: The emitter of the transistor Q6 is also connected to the emitter of the transistor Q5, and the collector of the transistor Q5 and the emitter of the transistor Q7 are both grounded.

6. The rear-cut single-fire wall dimmer according to claim 2, characterized in that: A capacitor C5 and a voltage stabilizing diode D5 are connected in parallel across the two ends of the resistor R14.

7. The rear-cut single-fire wall dimmer according to claim 2, characterized in that: The emitter of the transistor Q3 is also connected to the base of the transistor Q4; the anode of the three-terminal regulator is grounded.

8. The rear-cut single-fire wall dimmer according to claim 2, characterized in that: The resistor R4 is connected between the base and the emitter of the transistor Q4.

9. The rear-cut single-fire wall dimmer according to claim 2, characterized in that: The ground terminal of the low voltage difference linear regulator is grounded.

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