CN116420939A - Combustion control method and system for electronic cigarette based on smart secret key - Google Patents

Abstract

The present invention is applicable to the improvement application field of intelligent control technology, and provides a combustion control method of an electronic cigarette based on a smart key, including an electronic cigarette with a short-distance communication function and a smart key, and the combustion control method of an electronic cigarette based on a smart key Including unlocking steps and locking steps: in the unlocking step, start the smart key within the effective range of the electronic cigarette, establish a communication channel between the electronic cigarette and the smart key to unlock the electronic cigarette, and the internal combustion device of the electronic cigarette works normally; in the locking step, in the smart key When the key switch is turned off or out of the effective range of the electronic cigarette, the electronic cigarette cannot receive the matching agreement, the electronic cigarette is automatically locked, and its internal combustion appliances cannot work. It can be intelligently identified, automatically sensed, and the operation is more convenient. It can prevent teenagers from stealing e-cigarettes or mishandling e-cigarettes to bring safety risks.

Description

Combustion control method and system for electronic cigarette based on smart secret key

technical field

The invention belongs to the improved application field of intelligent control technology, and in particular relates to a combustion control method and system of an electronic cigarette based on an intelligent key.

Background technique

In order to better protect young people and prevent young people from secretly smoking e-cigarettes, it is necessary to set a child lock function for e-cigarettes.

Currently, there are mobile phones connected via Bluetooth, child lock function set through the mobile APP, and electronic cigarettes and heat-not-burn appliances unlocked/unlocked. But this method requires a mobile phone as an operating tool, and a specific APP needs to be installed as an operating system.

Contents of the invention

The purpose of the present invention is to provide a combustion control method and system for an electronic cigarette based on a smart key, aiming at solving the above-mentioned technical problems.

The present invention is realized in this way, a combustion control method of an electronic cigarette based on a smart key, including an electronic cigarette with a short-distance communication function and a smart key, and the combustion control method of an electronic cigarette based on a smart key includes an unlocking step and a locking step step:

The unlocking step is to activate the smart key within the effective range of the electronic cigarette, establish a communication channel between the electronic cigarette and the smart key to unlock the electronic cigarette, and the internal combustion device of the electronic cigarette works normally;

In the locking step, when the smart key switch is turned off or out of the effective range of the electronic cigarette, the electronic cigarette cannot receive the matching agreement, the electronic cigarette is automatically locked, and its internal combustion device cannot work.

A further technical solution of the present invention is: the unlocking step includes the following steps:

SJ1, the start-up state of the electronic cigarette scans the received signal at an interval of a preset time to identify whether it is an unlocking matching signal, if so, feeds back a successful matching signal to the smart key and requests to establish communication, if not, deletes the received signal;

SJ2. After the smart key interprets the feedback information, it sends a communication protocol to establish a communication connection to the electronic cigarette, and at the same time sends an unlock command signal;

SJ3. The electronic cigarette receives the signal and establishes a communication channel according to the communication protocol, and executes the received command to unlock the electronic cigarette so that the internal combustion appliance can work normally.

A further technical solution of the present invention is: the locking step includes the following steps:

SS1. Turn off the smart key switch or the smart key leaves the effective range of the electronic cigarette, so that the communication connection between the electronic cigarette and the smart key cannot be maintained;

SS2. If the electronic cigarette does not receive the communication signal within the preset time, it will be automatically locked so that the internal combustion appliance cannot work.

A further technical solution of the present invention is: the communication connection used in the unlocking step and the locking step adopts a short-distance bluetooth communication protocol.

Another object of the present invention is to provide a combustion control system for an electronic cigarette based on a smart key, including an electronic cigarette with a short-distance communication function and a smart key. The combustion control system for an electronic cigarette based on a smart key includes an unlocking module and a locking module. module

The unlocking module is used to start the smart key within the effective range of the electronic cigarette, the electronic cigarette and the smart key establish a communication channel to unlock the electronic cigarette, and the internal combustion device of the electronic cigarette works normally;

The locking module is used for closing the smart key switch or leaving the effective range of the electronic cigarette, and the electronic cigarette cannot receive the matching agreement, the electronic cigarette is automatically locked, and its internal combustion appliances cannot work.

A further technical solution of the present invention is: the unlocking module includes

The signal matching judging module is used to scan and receive the signal at a preset time interval in the start state of the electronic cigarette to identify whether it is an unlocking matching signal. If it is, it will feed back a successful matching signal to the smart key and request to establish communication. If not, it will send the received signal delete;

Establish a communication unit for the smart key to read the feedback information and send the communication protocol for establishing a communication connection to the electronic cigarette, and at the same time send an unlock command signal;

The unlocking unit is used for the electronic cigarette to receive signals to establish a communication channel according to the communication protocol, and execute the received instruction to unlock the electronic cigarette so that the internal combustion appliance can work normally.

A further technical solution of the present invention is: the locking module includes

The communication disconnection unit is used to turn off the smart key switch or the smart key leaves the effective range of the electronic cigarette so that the communication between the electronic cigarette and the smart key cannot be maintained;

The locking unit is used to automatically lock the electronic cigarette if it does not receive a communication signal within a preset time, so that the internal combustion device cannot work.

A further technical solution of the present invention is: the communication connection used in the unlocking module and the locking module adopts the bluetooth communication protocol for short-distance communication.

Another object of the present invention is to provide a smart key, which includes a shell, a key switch, a battery, a PCB circuit board, a bluetooth module and an indicator light, and the key switch, a battery, a PCB circuit board, and a bluetooth module and the indicator light are all arranged in the shell, the output end of the battery is connected to the input end of the PCB circuit board, the key switch, the bluetooth module and the indicator light are arranged on the PCB circuit board, and the battery The output end of the key switch is electrically connected to the input end of the key switch, the output end of the key switch is electrically connected to the input end of the Bluetooth module, and the output end of the Bluetooth module is connected to the input end of the indicator light.

A further technical solution of the present invention is: the Bluetooth module includes a chip U2, a capacitor C4, a capacitor C5, a capacitor C8, a capacitor C13, a resistor R3, an indicator light LED1, a resistor R2, a key switch SW1, a capacitor C12, an inductor L1, a capacitor C11, resistor R1, capacitor C10, capacitor C9, crystal oscillator Y1, capacitor C7, capacitor C6, capacitor C2, capacitor C1, capacitor C3, terminal U1, ceramic antenna ANT1 and battery BAT, the positive pole of the battery BAT is connected to the One end of the capacitor C3 and the third pin of the terminal U1, the second pin of the terminal U1 is respectively connected to one end of the capacitor C1, one end of the capacitor C2, the 48th pin of the chip U2, one end of the capacitor C5, and the chip U2 The 13th pin of the chip U2, one end of the capacitor C13, one end of the resistor R3, one end of the resistor R2, the 36th pin of the chip U2 and one end of the capacitor C6, the first pin of the chip U2 is grounded through the capacitor C8, the chip The 15th pin of U2 is connected to the cathode of the indicator LED1, the anode of the indicator LED1 is connected to the other end of the resistor R3, and the other end of the resistor R2 is respectively connected to the input terminal of the key switch and the 18th pin of the chip U2. The 30th pin of the chip U2 is respectively connected to one end of the capacitor C12 and one end of the inductor L1, and the other end of the inductor L1 is respectively connected to one end of the resistor R1 and one end of the capacitor C11, and the capacitor C11 The other end is connected to one end of the ceramic antenna ANT1, the 33rd pin of the chip U2 is connected to one end of the capacitor C10, and the 34th pin of the chip U2 is respectively connected to one end of the crystal oscillator Y1 and one end of the capacitor C9. The 35th pin of the chip U2 is respectively connected to the other end of the crystal oscillator Y1 and one end of the capacitor C7.

The beneficial effects of the present invention are: the electronic cigarette and the heat-not-burn appliance can be locked/unlocked without a mobile phone and an APP, and can be intelligently identified, automatically sensed, and the operation is more convenient. It can prevent teenagers from stealing e-cigarettes or mishandling e-cigarettes to bring safety risks.

Description of drawings

Fig. 1 is a flowchart of a combustion control method for an electronic cigarette based on a smart key provided by an embodiment of the present invention.

Fig. 2 is a schematic structural diagram of a smart key provided by an embodiment of the present invention.

Fig. 3 is a schematic cross-sectional structure diagram of the electronic cigarette provided by the embodiment of the present invention.

Fig. 4 is an electrical schematic diagram of the smart key provided by the embodiment of the present invention.

Fig. 5 is an electrical schematic diagram of the electronic cigarette provided by the embodiment of the present invention.

Detailed ways

Embodiments of the present invention are described in detail below, examples of which are shown in the drawings, wherein the same or similar reference numerals designate the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the figures are exemplary and are intended to explain the present invention and should not be construed as limiting the present invention.

In describing the present invention, it should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", The orientations or positional relationships indicated by "horizontal", "top", "bottom", "inner", "outer", etc. are based on the orientation or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than Nothing indicating or implying that a referenced device or element must have a particular orientation, be constructed, and operate in a particular orientation should therefore not be construed as limiting the invention. In addition, in the description of the present invention, "plurality" means two or more, unless otherwise specifically defined.

As shown in Figures 1-5, the combustion control method of the electronic cigarette based on the smart key provided by the present invention includes an electronic cigarette with a short-distance communication function and a smart key, and the combustion control method of the electronic cigarette based on the smart key includes an unlocking step and lock steps:

The unlocking step is to activate the smart key within the effective range of the electronic cigarette, the electronic cigarette and the smart key establish a communication channel to unlock the electronic cigarette, and the internal combustion device of the electronic cigarette works normally; the unlocking process also includes the following steps, SJ1, electronic cigarette Scan the received signal at an interval of preset time in the start state to identify whether it is an unlocking matching signal, if so, feed back a successful matching signal to the smart key and request to establish communication, if not, delete the received signal; SJ2, smart key interpretation feedback information Then send the communication protocol to establish a communication connection to the electronic cigarette, and at the same time send an unlock command signal; SJ3, the electronic cigarette receives the signal to establish a communication channel according to the communication protocol, and executes the receiving command to unlock the electronic cigarette so that the internal combustion device can work normally.

In the locking step, when the smart key switch is turned off or out of the effective range of the electronic cigarette, the electronic cigarette cannot receive the matching agreement, the electronic cigarette is automatically locked, and its internal combustion device cannot work. SS1. Turning off the smart key switch or the smart key leaves the effective range of the electronic cigarette, so that the communication between the electronic cigarette and the smart key cannot be maintained; SS2. The electronic cigarette is automatically locked when it fails to receive the communication signal within the preset time, so that the internal combustion device cannot work.

The smart key has a function switch, which allows the smart key to be turned on or off; the smart key communicates with electronic cigarettes or heat-not-burn appliances through the Bluetooth protocol, and they communicate through the Bluetooth connection. When the smart key is turned on , the electronic cigarette can automatically match the smart key through the Bluetooth protocol. After recognizing the signal of the smart key, the electronic cigarette is automatically unlocked and can be smoked; when the smart key switch is turned on and the smart key is turned off, the electronic cigarette cannot recognize the smart key. Then it is in a locked state, unable to start and unable to smoke.

Another object of the present invention is to provide a combustion control system for an electronic cigarette based on a smart key, including an electronic cigarette with a short-distance communication function and a smart key. The combustion control system for an electronic cigarette based on a smart key includes an unlocking module and a locking module. module

The unlocking module is used to start the smart key within the effective range of the electronic cigarette, the electronic cigarette and the smart key establish a communication channel to unlock the electronic cigarette, and the internal combustion device of the electronic cigarette works normally;

The locking module is used for closing the smart key switch or leaving the effective range of the electronic cigarette, and the electronic cigarette cannot receive the matching agreement, the electronic cigarette is automatically locked, and its internal combustion appliances cannot work.

The unlocking module includes

The signal matching judging module is used to scan and receive the signal at a preset time interval in the start state of the electronic cigarette to identify whether it is an unlocking matching signal. If it is, it will feed back a successful matching signal to the smart key and request to establish communication. If not, it will send the received signal delete;

Establish a communication unit for the smart key to read the feedback information and send the communication protocol for establishing a communication connection to the electronic cigarette, and at the same time send an unlock command signal;

The unlocking unit is used for the electronic cigarette to receive signals to establish a communication channel according to the communication protocol, and execute the received instruction to unlock the electronic cigarette so that the internal combustion appliance can work normally.

The locking module includes

The communication disconnection unit is used to turn off the smart key switch or the smart key leaves the effective range of the electronic cigarette so that the communication between the electronic cigarette and the smart key cannot be maintained;

The locking unit is used to automatically lock the electronic cigarette if it does not receive a communication signal within a preset time, so that the internal combustion device cannot work.

The communication connection used in the unlocking module and the locking module adopts the bluetooth communication protocol for short-distance communication.

Another object of the present invention is to provide a smart key, which includes a housing 10, a key switch, a battery, a PCB circuit board, a bluetooth module and an indicator light 30, the key switch, a battery, a PCB circuit board, a bluetooth The module and the indicator light 30 are all arranged in the housing 10, the output end of the battery is connected to the input end of the PCB circuit board, and the key switch, bluetooth module and indicator light 30 are arranged on the PCB circuit board Above, the output end of the battery is electrically connected to the input end of the key switch, the output end of the key switch is electrically connected to the input end of the Bluetooth module, and the output end of the Bluetooth module is connected to the indication light input. A circular indicator port and a button 20 with rebound function are arranged on the shell, and the button 20 is oval.

The bluetooth module includes chip U2, capacitor C4, capacitor C5, capacitor C8, capacitor C13, resistor R3, indicator light LED1, resistor R2, key switch SW1, capacitor C12, inductor L1, capacitor C11, resistor R1, capacitor C10, Capacitor C9, crystal oscillator Y1, capacitor C7, capacitor C6, capacitor C2, capacitor C1, capacitor C3, connection terminal U1, ceramic antenna ANT1 and battery BAT, the positive pole of the battery BAT is respectively connected to one end of the capacitor C3 and connection terminal U1 The third pin of the terminal U1, the second pin of the terminal U1 is respectively connected to one end of the capacitor C1, one end of the capacitor C2, the 48th pin of the chip U2, one end of the capacitor C5, the 13th pin of the chip U2, and the capacitor C13. One end, one end of the resistor R3, one end of the resistor R2, the 36th pin of the chip U2 and one end of the capacitor C6, the first pin of the chip U2 is grounded through the capacitor C8, and the 15th pin of the chip U2 is connected to the indicator light The cathode of LED1, the anode of the indicator light LED1 are connected to the other end of the resistor R3, and the other end of the resistor R2 is respectively connected to the input end of the key switch and the 18th pin of the chip U2, and the 18th pin of the chip U2 Pin 30 is respectively connected to one end of the capacitor C12 and one end of the inductor L1, the other end of the inductor L1 is respectively connected to one end of the resistor R1 and one end of the capacitor C11, and the other end of the capacitor C11 is connected to the ceramic antenna ANT1 The 33rd pin of the chip U2 is connected to one end of the capacitor C10, the 34th pin of the chip U2 is respectively connected to one end of the crystal oscillator Y1 and one end of the capacitor C9, and the 35th pin of the chip U2 is respectively Connect the other end of the crystal oscillator Y1 to one end of the capacitor C7.

As shown in Figure 4, the principle of smart key unlocking:

1. When the button SW1 is pressed, the level of the MCU pin P0.15 is pulled from high to low, and the MCU is woken up by an interrupt.

2. The MCU pin P0.15 turns from high to low, and the indicator LED1 lights up once.

3. The MCU signal passes through the antenna matching network (C12, L1, R1, C11) and the ceramic antenna (ANT1) from the MCU pin ANT, first sends the signal set by the communication protocol, and then sends other indication signals according to the number of times the button is pressed. Thereby controlling the opening and closing of the electronic cigarette.

4. After sending the signal, the MCU enters sleep mode and waits for the button to be pressed again.

As shown in Figure 5, the working principle of electronic cigarettes:

1. The electronic cigarette is powered by a battery, and the negative electrode of the battery protects the entire circuit (overcurrent, overvoltage, short circuit) through a lithium battery protection IC (U2).

2. The battery is stabilized at 3.3V through the LDO and supplied to the MCU

3. The MCU uses the MCU pin ANT to receive and send signals through the antenna matching network (C12, L1, R1, C11) and the ceramic antenna (ANT1). action,

4. After the electronic cigarette receives the opening signal, the button signal starts to be detected. If SW1 is pressed, the MCU pin P0.15 level will be pulled from high to low, and the MCU will be woken up by the interrupt.

MCU pin P0.20 outputs a high level, Q1 is turned on, and the current flows from +BAT through R5 and the heating wire. VSENS1 and R_AD1 detect the voltage across R5 to calculate the resistance of the heating wire.

5. After detecting that the resistance value is correct, the MCU pin P0.02 outputs a high level and turns on Q3. Then control Q2 to open. Current flows from +BAT through the heating wire, so that the heating wire works.

6. Release the button, the level of MCU pin P0.15 is pulled up from low, the MCU pin P0.02 stops outputting high level, and the heating wire stops heating.

7. Wait for the button to be pressed again.

A fixed communication protocol is set between the electronic cigarette and the smart key. Only through the communication protocol can the electronic cigarette device receive and send signals normally, otherwise the next step will not be performed. Press the button to wake up the Bluetooth IC. Bluetooth sends a set of fixed data through the matching circuit and antenna. When the electronic cigarette receives the signal in the protocol, a connection is established. The electronic cigarette set realizes the opening and closing function according to the signal of the smart key. The smart key enters the dormant standby mode, waiting for the next key press to turn on.

The invention is an electronic cigarette smart key, which is equipped with a function switch, which can make the smart key in the on or off state. The smart key communicates with electronic cigarettes or heat-not-burn appliances through the Bluetooth protocol. They communicate through Bluetooth connection. When the smart key is turned on, the electronic cigarette can automatically match the smart key through the Bluetooth protocol and recognize the smart key signal. Afterwards, the electronic cigarette is automatically in the unlocked state, and you can smoke; when the smart key switch is turned on to make the smart key in the off state, the electronic cigarette cannot recognize the smart key, and the electronic cigarette is in a locked state, unable to start, and unable to smoke. That is, the smart key controls whether the electronic cigarette or the heat-not-burn appliance can work, so as to prevent teenagers from stealing electronic cigarettes or mishandling electronic cigarettes to bring safety risks.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention should be included in the protection of the present invention. within range.

Claims (10)

1. A combustion control method for an electronic cigarette based on a smart key, characterized in that it includes an electronic cigarette with a short-distance communication function and a smart key, and the combustion control method for an electronic cigarette based on a smart key includes an unlocking step and a locking step: The unlocking step is to activate the smart key within the effective range of the electronic cigarette, establish a communication channel between the electronic cigarette and the smart key to unlock the electronic cigarette, and the internal combustion device of the electronic cigarette works normally; In the locking step, when the smart key switch is turned off or out of the effective range of the electronic cigarette, the electronic cigarette cannot receive the matching agreement, the electronic cigarette is automatically locked, and its internal combustion device cannot work. 2. The combustion control method based on the smart key electronic cigarette according to claim 1, wherein the unlocking step comprises the following steps: SJ1, the start-up state of the electronic cigarette scans the received signal at an interval of a preset time to identify whether it is an unlocking matching signal, if so, feeds back a successful matching signal to the smart key and requests to establish communication, if not, deletes the received signal; SJ2. After the smart key interprets the feedback information, it sends a communication protocol to establish a communication connection to the electronic cigarette, and at the same time sends an unlock command signal; SJ3. The electronic cigarette receives the signal and establishes a communication channel according to the communication protocol, and executes the received command to unlock the electronic cigarette so that the internal combustion appliance can work normally. 3. The combustion control method based on the smart key electronic cigarette according to claim 2, wherein the locking step comprises the following steps: SS1. Turn off the smart key switch or the smart key leaves the effective range of the electronic cigarette, so that the communication connection between the electronic cigarette and the smart key cannot be maintained; SS2. If the electronic cigarette does not receive the communication signal within the preset time, it will be automatically locked so that the internal combustion appliance cannot work. 4. The combustion control method based on the smart key electronic cigarette according to claim 3, characterized in that, the communication connection used in the unlocking step and the locking step adopts a short-distance Bluetooth communication protocol. 5. A combustion control system based on an electronic cigarette with a smart key, characterized in that it includes an electronic cigarette with a short-distance communication function and a smart key, and the combustion control system based on an electronic cigarette with a smart key includes an unlocking module and a locking module The unlocking module is used to start the smart key within the effective range of the electronic cigarette, the electronic cigarette and the smart key establish a communication channel to unlock the electronic cigarette, and the internal combustion device of the electronic cigarette works normally; The locking module is used for closing the smart key switch or leaving the effective range of the electronic cigarette, and the electronic cigarette cannot receive the matching agreement, the electronic cigarette is automatically locked, and its internal combustion appliances cannot work. 6. The combustion control system based on the smart key electronic cigarette according to claim 5, wherein the unlocking module includes The signal matching judging module is used to scan and receive the signal at a preset time interval in the start state of the electronic cigarette to identify whether it is an unlocking matching signal. If it is, it will feed back a successful matching signal to the smart key and request to establish communication. If not, it will send the received signal delete; Establish a communication unit for the smart key to read the feedback information and send the communication protocol for establishing a communication connection to the electronic cigarette, and at the same time send an unlock command signal; The unlocking unit is used for the electronic cigarette to receive signals to establish a communication channel according to the communication protocol, and execute the received instruction to unlock the electronic cigarette so that the internal combustion appliance can work normally. 7. The combustion control system based on the smart key electronic cigarette according to claim 6, wherein the locking module includes The communication disconnection unit is used to turn off the smart key switch or the smart key leaves the effective range of the electronic cigarette so that the communication between the electronic cigarette and the smart key cannot be maintained; The locking unit is used to automatically lock the electronic cigarette if it does not receive a communication signal within a preset time, so that the internal combustion device cannot work. 8 . The combustion control system based on the smart key electronic cigarette according to claim 7 , wherein the communication connection used in the unlocking module and the locking module adopts a Bluetooth communication protocol for short-distance communication. 9. A kind of smart key, it is characterized in that, described smart key comprises shell, key switch, battery, PCB circuit board, bluetooth module and indicator light, described key switch, battery, PCB circuit board, bluetooth module and indication The lamps are all arranged in the shell, the output end of the battery is connected to the input end of the PCB circuit board, the key switch, bluetooth module and indicator light are arranged on the PCB circuit board, and the output of the battery The terminal is electrically connected to the input terminal of the key switch, the output terminal of the key switch is electrically connected to the input terminal of the Bluetooth module, and the output terminal of the Bluetooth module is connected to the input terminal of the indicator light. 10. The smart key according to claim 9, wherein the Bluetooth module includes a chip U2, a capacitor C4, a capacitor C5, a capacitor C8, a capacitor C13, a resistor R3, an indicator LED1, a resistor R2, and a key switch SW1 , capacitor C12, inductor L1, capacitor C11, resistor R1, capacitor C10, capacitor C9, crystal oscillator Y1, capacitor C7, capacitor C6, capacitor C2, capacitor C1, capacitor C3, terminal U1, ceramic antenna ANT1 and battery BAT, the The positive pole of the battery BAT is respectively connected to one end of the capacitor C3 and the third pin of the terminal U1, and the second pin of the terminal U1 is respectively connected to one end of the capacitor C1, one end of the capacitor C2, and the 48th pin of the chip U2 , one end of the capacitor C5, the 13th pin of the chip U2, one end of the capacitor C13, one end of the resistor R3, one end of the resistor R2, the 36th pin of the chip U2 and one end of the capacitor C6, the first pin of the chip U2 passes through the The capacitor C8 is grounded, the 15th pin of the chip U2 is connected to the cathode of the indicator LED1, the anode of the indicator LED1 is connected to the other end of the resistor R3, and the other end of the resistor R2 is respectively connected to the button switch. The input end and the 18th pin of the chip U2, the 30th pin of the chip U2 are respectively connected to one end of the capacitor C12 and one end of the inductor L1, and the other end of the inductor L1 is respectively connected to one end of the resistor R1 and the capacitor C11 one end of the capacitor C11, the other end of the capacitor C11 is connected to one end of the ceramic antenna ANT1, the 33rd pin of the chip U2 is connected to one end of the capacitor C10, and the 34th pin of the chip U2 is respectively connected to the crystal oscillator Y1 One end and one end of the capacitor C9, and the 35th pin of the chip U2 are respectively connected to the other end of the crystal oscillator Y1 and one end of the capacitor C7.

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