A hand-held moisture detector circuit

Abstract

The application discloses a kind of handheld humidity detector circuit, mainly solve the problem of greater detection error of existing humidity detector.The circuit includes high-frequency microwave module for generating microwave and receiving feedback signal, humidity display module connected with high-frequency microwave module for converting humidity analog voltage fed back by high-frequency microwave module into digital value for display, and power module for powering high-frequency microwave module and humidity display module.Through the above design, the application improves the circuit of high-frequency microwave module, in different test environments, according to the difference of the measured material, set different gears, generate different frequency electromagnetic waves, get feedback signal through flyback voltage transformer, use full-bridge rectifier circuit to get measured analog voltage value, the analog quantity can be displayed through three-bit and a half AD conversion IC and then through LCD code screen actual humidity value, the feedback signal receiving is stable, which greatly improves the measurement accuracy of the detector.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of electronic circuit, in particular, it relates to a hand-held humidity detector circuit. BACKGROUND

[0002] With the development of modern industrial and agricultural technology and the improvement of people's requirements for living environment and quality, the measurement and control of humidity become increasingly important. For example, in the workshop with dust operation and electronic product production, the humidity in the room is low due to water leakage, and static electricity is generated, which often leads to explosion accidents. In the production process of large-scale integrated circuits, the humidity is lower than 30% due to water leakage, which easily generates static electricity and affects production. The humidity in the warehouse is too large, which causes the stored materials to deteriorate or become bad. In the aspects of seedling raising, cultivation, production and preservation in agriculture, the measurement and control of humidity are also needed.

[0003] The measurement of the humidity detector uses the electromagnetic wave technology measurement principle. According to the difference of the measured material, different positions are set to generate electromagnetic waves of different frequencies, so as to obtain the analog quantity of the material humidity, and then the analog quantity is converted into digital quantity to display the data. However, in the existing humidity detector, the microwave frequency generated by the microwave generating circuit is unstable, which often makes the detection error of the humidity detector larger, and affects the judgment of the actual environmental humidity. SUMMARY

[0004] The purpose of the present application is to provide a hand-held humidity detector circuit, which mainly solves the problem of large detection error of the existing humidity detector.

[0005] In order to achieve the above purpose, the technical scheme adopted by the present application is as follows:

[0006] A hand-held humidity detector circuit, comprising a high-frequency microwave module for generating microwaves and receiving feedback signals, a humidity display module connected to the high-frequency microwave module for converting humidity analog voltage feedback by the high-frequency microwave module into digital values for display, and a power module for powering the high-frequency microwave module and the humidity display module; the high-frequency microwave module comprises a resistor R20 connected to the power module, a potentiometer VR6 with the second and first pins connected to the resistor R20 and the common terminal of the power module, a potentiometer VR1 connected to the third pin of the potentiometer VR6, a potentiometer VR3 with the third pin connected to the other end of the resistor R20, an electrolytic capacitor E5 with the negative terminal connected to the first pin of the potentiometer VR3, a flyback voltage transformer T1 with the seventh pin connected to the positive terminal of the electrolytic capacitor E5, a full-bridge rectifier circuit with the AC input connected to the fourth and fifth pins of the flyback voltage transformer T1, a resistor R17 connected to the DC negative terminal of the full-bridge rectifier circuit, a capacitor C6 connected to the other end of the resistor R17, a resistor R27 with one end connected to the other end of the capacitor C6 and the other end connected to the third pin of the potentiometer VR1, a resistor R26 with one end connected to the common terminal of the capacitor C6 and the resistor R27 and the other end grounded, a transistor Q3 with the emitter connected to the third pin of the flyback voltage transformer T1 through the capacitor C1, a capacitor C8 connected between the base of the transistor Q3 and the eighth pin of the flyback voltage transformer T1, a capacitor C9 connected between the collector of the transistor Q3 and the eighth pin of the flyback voltage transformer T1, a resistor R18 connected between the collector of the transistor Q3 and the sixth pin of the flyback voltage transformer T1, a capacitor C3 with one end connected to the emitter of the transistor Q3 and the other end connected to the DC negative terminal of the full-bridge rectifier circuit, a multi-frequency signal transmitting circuit connected in parallel to the capacitor C3, and a capacitor C115 with one end connected to the emitter of the transistor Q3 and the other end grounded; wherein the tenth pin of the flyback voltage transformer T1 is connected to the power module through the resistor R28, the ninth pin of the flyback voltage transformer T1 is connected to the base of the transistor Q3, the emitter of the transistor Q3 is connected to the DC positive terminal of the full-bridge rectifier circuit through the common terminal of the capacitor C6, the resistor R27 and the resistor R26, the second pin of the potentiometer VR3 and the DC positive terminal of the full-bridge rectifier circuit are both connected to the humidity display module.

[0007] Further, in the present application, the multi-frequency signal transmitting circuit comprises an encoding switch SW1 connected to the DC negative terminal of the full-bridge rectifier circuit, a resistor R2 connected between the first pin of the encoding switch SW1 and the emitter of the transistor Q3, a resistor R3 connected between the second pin of the encoding switch SW1 and the emitter of the transistor Q3, a resistor R4 connected between the fourth pin of the encoding switch SW1 and the emitter of the transistor Q3, and a resistor R5 connected between the fifth pin of the encoding switch SW1 and the emitter of the transistor Q3.

[0008] Further, in the application, the humidity display module comprises an AD converter connected with the 2nd pin of the potentiometer VR3, a capacitor C14 connected between the REF_IN pin and the CREF+ pin of the AD converter, a capacitor C5 connected between the CREF- pin and the CREF+ pin of the AD converter, a capacitor C4, a resistor R15 and a resistor C4-1 connected with the A-Z pin, the BUFF pin and the INT pin of the AD converter respectively, a capacitor C10 connected between the OCS_1 pin and the OCS_3 pin of the AD converter, a resistor R19 connected between the OCS_1 pin and the OCS_2 pin of the AD converter, and an LCD display screen connected with the AD converter; wherein the REF_LO pin, the COMMON pin and the IN_LO pin of the AD converter are connected with the positive pole of the full-bridge rectifier circuit, the other ends of the capacitor C4, the resistor R15 and the resistor C4-1 are connected together, and the V+ pin of the AD converter is connected with the power module.

[0009] Further, in the application, the power module comprises a dual D-type flip-flop U1, a power supply battery connected with the 3rd pin of the dual D-type flip-flop U1 through the key switch K1, a resistor R10-1 connected with the 4th pin of the dual D-type flip-flop U1, a capacitor C16 connected with the other end of the resistor R10-1 and grounded, a voltage output adjusting module connected with the other end of the capacitor C16 and the output end of the power supply battery, a resistor R9-1 connected with the 6th pin of the dual D-type flip-flop U1 at one end and grounded at the other end, a capacitor C8-1 connected with the 6th pin of the dual D-type flip-flop U1 at one end and the output end of the power supply battery at the other end, a triode Q31 with the base connected with the 1st pin of the dual D-type flip-flop U1 through the resistor R31, an electrolytic capacitor E3 with the positive pole connected with the emitter of the triode Q31 and the output end of the power supply battery and the negative pole grounded, a resistor R8-1 connected with the 7th, 8th, 10th and 11th pins of the dual D-type flip-flop U1 at one end, and a capacitor C7-1 connected with the 7th, 8th, 10th and 11th pins of the dual D-type flip-flop U1 at one end and the other end; wherein the collector of the triode Q1 is taken as the output end of the power module to supply power for other modules.

[0010] Further, in the application, the voltage output adjusting module comprises a resistor R6 connected with the output end of the power supply battery, an electrolytic capacitor E4 with the positive pole connected with the other end of the resistor R6 and the negative pole grounded, the two fixed ends connected with the two ends of the electrolytic capacitor E4, and a potentiometer U3 with the sliding end connected with the output end of the power supply battery.

[0011] Further, in the application, the humidity display module further comprises a digital display retention module; the digital display retention module comprises a flip-flop U2 connected with the LCD display screen through the 12th pin, a resistor R23 connected with the 1st pin of the flip-flop U2, a triode Q2 of which the base is connected with the other end of the resistor R23 through the resistor R24 and the emitter is connected with the 12th pin of the flip-flop U2, a resistor R21 of which one end is connected with the collector of the triode Q2 and the other end is connected with the 13th pin of the flip-flop U2, a capacitor C11 of which one end is connected with the 2nd and 3rd pins of the flip-flop U2 and the other end is connected with the 14th pin of the flip-flop U2, a capacitor C15 of which one end is connected with the 2nd and 3rd pins of the flip-flop U2 through the resistor R22 and the other end is grounded, a key switch S1 of which one end is connected with the 1st pin of the flip-flop U2 and the other end is connected with the common end of the capacitor C15 and the resistor R22, a resistor R25 connected with the 5th, 9th and 11th pins of the flip-flop U2, and a capacitor C31 of which one end is connected with the other end of the resistor R25 and the other end is connected with the output end of the power module; wherein the 13th pin of the flip-flop U2 is further connected with the BP / GND pin of the AD converter, and the 4th pin of the flip-flop U2 is further connected with the HOLD* pin of the AD converter.

[0012] Further, in the application, the data transmission module connected with the high-frequency microwave module and the power module, the data transmission module comprises a communication chip U5 of ESP32F type, a switch K2 of which one end is connected with the EN pin of the communication chip U5 and the other end is grounded, a resistor R703 connected between the EN pin and the 3V3 pin of the communication chip U5, a resistor R705 connected between the SENVP pin and the 3V3 pin of the communication chip U5, a resistor R704 connected between the SENVN pin and the 3V3 pin of the communication chip U5, a resistor R710 connected between the IO34 pin and the 3V3 pin of the communication chip U5, a resistor R709 connected between the IO34 pin and the 3V3 pin of the communication chip U5, a capacitor C1 of which one end is connected with the 3V3 pin of the communication chip U5 and the other end is grounded, an electrolytic capacitor C12 of which the positive electrode is connected with the 3V3 pin of the communication chip U5 and the negative electrode is grounded, a resistor R7 of which one end is connected with the IO17 pin of the communication chip U5 and the other end is connected with the common end of the resistor R17 and the capacitor C6 in the high-frequency microwave module, a resistor R1 of which one end is connected with the IO17 pin of the communication chip U5 and the other end is connected with the output end of the power module, a resistor R8 connected between the IO17 pin and the IO16 pin of the communication chip U5, and a switch K1 of which one end is connected with the IO0 pin of the communication chip U5 and the other end is grounded.

[0013] Compared with the prior art, the application has the following beneficial effects:

[0014] (1) This invention utilizes the measurement principle of electromagnetic wave technology. By improving the circuit of the high-frequency microwave module, different levels are set according to the different materials being tested under different test environments to generate electromagnetic waves of different frequencies. Feedback signals are obtained through a flyback voltage transformer, and the measured analog voltage value is obtained through a full-bridge rectifier circuit. This analog quantity can be converted to the actual humidity value by a three-and-a-half-digit AD conversion IC and then displayed on an LCD screen. The feedback signal reception is stable, which greatly improves the measurement accuracy of the detector.

[0015] (2) By setting up a data transmission module, the present invention can connect to the main device through the wifi / Bluetooth module on the module, and send the humidity value to the main device according to a custom protocol, which facilitates the recording and storage of data. Attached Figure Description

[0016] Fig. 1 This is a circuit diagram of the high-frequency microwave module in this invention.

[0017] Fig. 2 This is a circuit diagram of the power supply module in this invention.

[0018] Fig. 3 This is a circuit diagram of the humidity display module in this invention.

[0019] Fig. 4 This is a circuit diagram of the digital display holding module in this invention.

[0020] Fig. 5 This is a circuit diagram of the data transmission module in this invention. Detailed Implementation

[0021] The present invention will be further described below with reference to the accompanying drawings and embodiments. The embodiments of the present invention include, but are not limited to, the following embodiments.

[0022] Example

[0023] like Figs. 1-5 As shown, the present invention discloses a handheld humidity detector circuit, including a high-frequency microwave module for generating microwaves and receiving feedback signals, a humidity display module connected to the high-frequency microwave module for converting the humidity analog voltage fed back by the high-frequency microwave module into a digital value for display, and a power supply module for supplying power to the high-frequency microwave module and the humidity display module.

[0024] In the embodiment, the high-frequency microwave module comprises a resistor R20 connected to the power module at one end, a potentiometer VR6 with the second and first pins connected to the resistor R20 and the common terminal of the power module, a potentiometer VR1 connected to the third pin of the potentiometer VR6, a potentiometer VR3 with the third pin connected to the other end of the resistor R20, an electrolytic capacitor E5 with the negative terminal connected to the first pin of the potentiometer VR3, a flyback voltage transformer T1 with the seventh pin connected to the positive terminal of the electrolytic capacitor E5, a full-bridge rectifier circuit with the AC input connected to the fourth and fifth pins of the flyback voltage transformer T1, a resistor R17 connected to the DC negative terminal of the full-bridge rectifier circuit, a capacitor C6 connected to the other end of the resistor R17, a resistor R27 connected to the other end of the capacitor C6 and the third pin of the potentiometer VR1, a resistor R26 connected to the common terminal of the capacitor C6 and the resistor R27 and grounded, a transistor Q3 with the emitter connected to the third pin of the flyback voltage transformer T1 via the capacitor C1, a capacitor C8 connected between the base of the transistor Q3 and the eighth pin of the flyback voltage transformer T1, a capacitor C9 connected between the collector of the transistor Q3 and the eighth pin of the flyback voltage transformer T1, a resistor R18 connected between the collector of the transistor Q3 and the sixth pin of the flyback voltage transformer T1, a capacitor C3 connected to the emitter of the transistor Q3 and the DC negative terminal of the full-bridge rectifier circuit at the other end, a multi-frequency signal transmitting circuit connected in parallel to the capacitor C3, and a capacitor C115 connected to the emitter of the transistor Q3 at one end and grounded at the other end; wherein the tenth pin of the flyback voltage transformer T1 is connected to the power module via the resistor R28, the ninth pin of the flyback voltage transformer T1 is connected to the base of the transistor Q3, the emitter of the transistor Q3 is connected to the DC positive terminal of the full-bridge rectifier circuit via the common terminal of the capacitor C6, the resistor R27, and the resistor R26, and the second pin of the potentiometer VR3 and the DC positive terminal of the full-bridge rectifier circuit are both connected to the humidity display module. In the circuit, the resistor R20 and the capacitor C3 form an RC oscillation circuit to generate a signal of a certain frequency which is transmitted through the antenna, and the frequency value of the signal can be adjusted by the measurement range of the handheld measuring instrument to meet the corresponding frequency required by different materials; then the feedback signal is obtained through the flyback voltage transformer; and then the analog voltage value of the measurement is obtained through the full-bridge rectifier circuit, and the analog voltage is converted and transmitted to the humidity display module to display the actual humidity value.

[0025] In the embodiment, the multi-frequency signal transmitting circuit comprises an encoder switch SW1 connected to the DC negative terminal of the full-bridge rectifier circuit, a resistor R2 connected between the first pin of the encoder switch SW1 and the emitter of the transistor Q3, a resistor R3 connected between the second pin of the encoder switch SW1 and the emitter of the transistor Q3, a resistor R4 connected between the fourth pin of the encoder switch SW1 and the emitter of the transistor Q3, and a resistor R5 connected between the fifth pin of the encoder switch SW1 and the emitter of the transistor Q3. The model of the encoder switch SW1 is SS-24F01-G6, and there are four gears. The signal strength is attenuated by switching the external key switch to different resistance values, so as to match the humidity measurement of different materials. The first gear is used for measuring marble, the second gear is used for measuring concrete and cement wall surface, the third gear is used for measuring brick and firebrick, and the fourth gear is used for measuring cement mortar.

[0026] In the embodiment, the humidity display module comprises an AD converter with the REF_IN pin connected to the second pin of the potentiometer VR3, a capacitor C14 connected between the REF_IN pin and the CREF+ pin of the AD converter, a capacitor C5 connected between the CREF- pin and the CREF+ pin of the AD converter, a capacitor C4, a resistor R15 and a resistor C4-1 connected to the A-Z pin, the BUFF pin and the INT pin of the AD converter respectively, a capacitor C10 connected between the OCS_1 pin and the OCS_3 pin of the AD converter, a resistor R19 connected between the OCS_1 pin and the OCS_2 pin of the AD converter, and an LCD display screen connected to the AD converter; wherein the REF_LO pin, the COMMON pin and the IN_LO pin of the AD converter are connected to the DC positive terminal of the full-bridge rectifier circuit, the other ends of the capacitor C4, the resistor R15 and the resistor C4-1 are connected together, and the V+ pin of the AD converter is connected to the power module. In the circuit, the AD converter chip ICL7106 containing a seven-segment decoder, a display driver, a reference power supply and a clock system and containing a back electrode driving line is mainly used for liquid crystal display. The chip ICL7106 is used to convert the analog voltage value into a digital voltage value, and then the actual humidity value is displayed on the LCD digital code screen.

[0027] In the embodiment, the power module comprises a dual D-type flip-flop U1, a power supply battery connected to the 3rd pin of the dual D-type flip-flop U1 through a key switch K1, a resistor R10-1 connected to the 4th pin of the dual D-type flip-flop U1, a capacitor C16 connected to the other end of the resistor R10-1 and grounded, a voltage output adjusting module connected to the other end of the capacitor C16 and the output end of the power supply battery, a resistor R9-1 connected to the 6th pin of the dual D-type flip-flop U1 at one end and grounded at the other end, a capacitor C8-1 connected to the 6th pin of the dual D-type flip-flop U1 at one end and to the output end of the power supply battery at the other end, a triode Q31 with the base connected to the 1st pin of the dual D-type flip-flop U1 through a resistor R31, an electrolytic capacitor E3 with the positive pole connected to the emitter of the triode Q31 and the output end of the power supply battery and the negative pole grounded, a resistor R8-1 connected to the 7th, 8th, 10th and 11th pins of the dual D-type flip-flop U1 at one end, and a capacitor C7-1 connected to the 7th, 8th, 10th and 11th pins of the dual D-type flip-flop U1 at one end and to the other end of the resistor R8-1 at the other end; wherein the collector of the triode Q31 serves as the output end of the power module to supply power to other modules.

[0028] The voltage output adjusting module comprises a resistor R6 connected to the output end of the power supply battery, an electrolytic capacitor E4 with the positive pole connected to the other end of the resistor R6 and the negative pole grounded, a potentiometer U3 with both fixed ends connected to the two ends of the electrolytic capacitor E4 and the sliding end connected to the output end of the power supply battery. The power supply battery provides a 6v voltage power supply by connecting four 7# batteries in series; the voltage output adjusting module adjusts the voltage output value by the adjustable voltage dividing resistor; the dual D-type flip-flop U1 and the light touch key switch K1 form a switch circuit, and the flip-flop changes state once every time the power switch is pressed to turn on or off the triode Q31 responsible for the power switch control, thereby realizing the power switch of the humidity meter, and the triode Q31 provides power to each module at the collector output.

[0029] In the embodiment, the humidity display module further comprises a digital display holding module; the digital display holding module comprises a flip-flop U2 connected with the LCD display screen at the 12th pin, a resistor R23 connected with the 1st pin of the flip-flop U2, a triode Q2 with the base connected with the other end of the resistor R23 through the resistor R24 and the emitter connected with the 12th pin of the flip-flop U2, a resistor R21 with one end connected with the collector of the triode Q2 and the other end connected with the 13th pin of the flip-flop U2, a capacitor C11 with one end connected with the 2nd and 3rd pins of the flip-flop U2 and the other end connected with the 14th pin of the flip-flop U2, a capacitor C15 with one end connected with the 2nd and 3rd pins of the flip-flop U2 through the resistor R22 and the other end grounded, a key switch S1 with one end connected with the 1st pin of the flip-flop U2 and the other end connected with the common end of the capacitor C15 and the resistor R22, a resistor R25 with one end connected with the 5th, 9th and 11th pins of the flip-flop U2, and a capacitor C31 with one end connected with the other end of the resistor R25 and the other end connected with the output end of the power module; wherein the 13th pin of the flip-flop U2 is further connected with the BP / GND pin of the AD converter, and the 4th pin of the flip-flop U2 is further connected with the HOLD* pin of the AD converter. The circuit provides a low-level input signal through the position key switch S1, and simultaneously outputs a high-level signal through the channel 1, and provides a period of trigger signal for the humidity display module through the residual value of the capacitor, so as to realize the value display holding function of the humidity display module.

[0030] In the embodiment, the humidity meter detection circuit further comprises a data transmission module connected with the high-frequency microwave module and the power module, the data transmission module comprises a communication chip U5 of ESP32F type, a switch K2 having one end connected with an EN pin of the communication chip U5 and the other end grounded, a resistor R703 connected between the EN pin and a 3V3 pin of the communication chip U5, a resistor R705 connected between a SENVP pin and the 3V3 pin of the communication chip U5, a resistor R704 connected between a SENVN pin and the 3V3 pin of the communication chip U5, a resistor R710 connected between an IO34 pin and the 3V3 pin of the communication chip U5, a resistor R709 connected between the IO34 pin and the 3V3 pin of the communication chip U5, a capacitor C1 having one end connected with the 3V3 pin of the communication chip U5 and the other end grounded, an electrolytic capacitor C12 having a positive electrode connected with the 3V3 pin of the communication chip U5 and a negative electrode grounded, a resistor R7 having one end connected with an IO17 pin of the communication chip U5 and the other end connected with a common terminal of a resistor R17 and a capacitor C6 in the high-frequency microwave module, a resistor R1 having one end connected with the IO17 pin of the communication chip U5 and the other end connected with an output terminal of the power module, a resistor R8 connected between the IO17 pin and an IO16 pin of the communication chip U5, and a switch K1 having one end connected with an IO0 pin of the communication chip U5 and the other end grounded. The module is relatively simple in hardware design, connects the humidity analog voltage value generated by the high-frequency microwave module to the ADC sampling pin of the communication chip, calculates the digital voltage value in the chip, and sends the actual humidity value to the paired communication device through the wireless Bluetooth antenna.

[0031] Through the above design, the application improves the circuit of the high-frequency microwave module, sets different gears according to different materials to be tested in different test environments, generates electromagnetic waves of different frequencies, obtains feedback signals through the flyback voltage transformer, obtains the measured analog voltage value through the full-bridge rectifier circuit, and displays the actual humidity value through the three-bit and a half AD conversion IC and the LCD code screen. The feedback signal receiving is stable, and the measurement accuracy of the detector is greatly improved. Therefore, the application has high use value and promotion value.

[0032] The above embodiment is only one of the preferred embodiments of the application and should not be used to limit the protection scope of the application. Any modification or polishing without substantial meaning made within the main design idea and spirit of the application, which still solves the technical problems consistent with the application, should be included in the protection scope of the application.

Claims

1. A hand-held moisture detector circuit, comprising: The application relates to a humidity display module, which comprises a high-frequency microwave module for generating microwaves and receiving feedback signals, a humidity display module connected with the high-frequency microwave module for converting humidity analog voltage fed back by the high-frequency microwave module into digital values for display, and a power module for supplying power to the high-frequency microwave module and the humidity display module; the high-frequency microwave module comprises a resistor R20 connected with the power module at one end, a potentiometer VR6 connected with the resistor R20 and the common terminal of the power module at the 2nd and 1st pins, a potentiometer VR1 connected with the 3rd pin of the potentiometer VR6, a potentiometer VR3 connected with the other end of the resistor R20 at the 3rd pin, an electrolytic capacitor E5 connected with the 1st pin of the potentiometer VR3 at the negative pole, a flyback voltage transformer T1 connected with the positive pole of the electrolytic capacitor E5 at the 7th pin, a full-bridge rectifier circuit connected with the 4th and 5th pins of the flyback voltage transformer T1 at the alternating current input end, a resistor R17 connected with the direct current negative terminal of the full-bridge rectifier circuit, a capacitor C6 connected with the other end of the resistor R17, a resistor R27 connected with the other end of the capacitor C6 and the 3rd pin of the potentiometer VR1 at one end, a resistor R26 connected with the common terminal of the capacitor C6 and the resistor R27 at one end and grounded at the other end, a triode Q3 connected with the 3rd pin of the flyback voltage transformer T1 at the emitter through a capacitor VC1, a capacitor C8 connected between the base of the triode Q3 and the 8th pin of the flyback voltage transformer T1, a capacitor C9 connected between the collector of the triode Q3 and the 8th pin of the flyback voltage transformer T1, a resistor R18 connected between the collector of the triode Q3 and the 6th pin of the flyback voltage transformer T1, a capacitor C3 connected with the emitter of the triode Q3 at one end and with the direct current negative terminal of the full-bridge rectifier circuit at the other end, a multi-frequency signal transmitting circuit connected in parallel to the capacitor C3, and a capacitor C115 connected with the emitter of the triode Q3 at one end and grounded at the other end; wherein the 10th pin of the flyback voltage transformer T1 is connected with the power module through a resistor R28, the 9th pin of the flyback voltage transformer T1 is connected with the base of the triode Q3, the emitter of the triode Q3 is connected with the direct current positive terminal of the full-bridge rectifier circuit through the common terminal of the capacitor C6, the resistor R27 and the resistor R26, the 2nd pin of the potentiometer VR3 and the direct current positive terminal of the full-bridge rectifier circuit are connected with the humidity display module; The multi-frequency signal transmitting circuit comprises an encoder switch SW1 connected with the direct current negative terminal of the full-bridge rectifier circuit, a resistor R2 connected between the 1st pin of the encoder switch SW1 and the emitter of the triode Q3, a resistor R3 connected between the 2nd pin of the encoder switch SW1 and the emitter of the triode Q3, a resistor R4 connected between the 4th pin of the encoder switch SW1 and the emitter of the triode Q3, and a resistor R5 connected between the 5th pin of the encoder switch SW1 and the emitter of the triode Q3; wherein the model of the encoder switch SW1 is SS-24F01-G6.

2. The hand-held humidity detector circuit of claim 1, wherein, The humidity display module comprises an AD converter connected with the REF_HI pin and the 2nd pin of the potentiometer VR3, a capacitor C14 connected between the REF_HI pin and the CREF+ pin of the AD converter, a capacitor C5 connected between the CREF- pin and the CREF+ pin of the AD converter, a capacitor C4, a resistor R15 and a resistor C4-1 connected with the A-Z pin, the BUFF pin and the INT pin of the AD converter respectively, a capacitor C10 connected between the OCS_1 pin and the OCS_3 pin of the AD converter, a resistor R19 connected between the OCS_1 pin and the OCS_2 pin of the AD converter, and an LCD display screen connected with the AD converter; wherein the REF_LO pin, the COMMON pin and the IN_LO pin of the AD converter are connected with the direct current positive pole end of the full-bridge rectifier circuit, the other ends of the capacitor C4, the resistor R15 and the resistor C4-1 are connected together, the V+ pin of the AD converter is connected with the power module.

3. A hand-held moisture detector circuit according to claim 2, wherein The power module comprises a double-path D-type flip-flop U1, a power supply battery connected with the 3rd pin of the double-path D-type flip-flop U1 through the key switch K1, a resistor R10-1 connected with the 4th pin of the double-path D-type flip-flop U1, a capacitor C16 connected with the other end of the resistor R10-1 and grounded, a voltage output adjusting module connected with the other end of the capacitor C16 and the output end of the power supply battery, a resistor R9-1 connected with the 6th pin of the double-path D-type flip-flop U1 at one end and grounded at the other end, a capacitor C8-1 connected with the 6th pin of the double-path D-type flip-flop U1 at one end and with the output end of the power supply battery at the other end, a triode Q31 with the base connected with the 1st pin of the double-path D-type flip-flop U1 through the resistor R31, an electrolytic capacitor E3 with the positive pole connected with the emitter of the triode Q31 and the output end of the power supply battery and the negative pole grounded, a resistor R8-1 connected with the 7th, 8th, 10th and 11th pins of the double-path D-type flip-flop U1 at one end, and a capacitor C7-1 connected with the 7th, 8th, 10th and 11th pins of the double-path D-type flip-flop U1 at one end and with the other end connected with the 7th, 8th, 10th and 11th pins of the double-path D-type flip-flop U1; wherein the collector of the triode U1 is taken as the output end of the power module to supply power to other modules.

4. The hand-held humidity detector circuit of claim 3, wherein, The voltage output adjusting module comprises a resistor R6 connected with the output end of the power supply battery, an electrolytic capacitor E4 with the positive pole connected with the other end of the resistor R6 and the negative pole grounded, the two fixed ends connected with the two ends of the electrolytic capacitor E4, and a potentiometer U3 with the sliding end connected with the output end of the power supply battery.

5. A hand-held moisture detector circuit according to claim 4, wherein The humidity display module further comprises a digital display retention module; the digital display retention module comprises a flip-flop U2 connected with the LCD display screen through the 12th pin, a resistor R23 connected with the 1st pin of the flip-flop U2, a triode Q2 of which the base is connected with the other end of the resistor R23 through the resistor R24 and the emitter is connected with the 12th pin of the flip-flop U2, a resistor R21 of which one end is connected with the collector of the triode Q2 and the other end is connected with the 13th pin of the flip-flop U2, a capacitor C11 of which one end is connected with the 2nd and 3rd pins of the flip-flop U2 and the other end is connected with the 14th pin of the flip-flop U2, a capacitor C15 of which one end is connected with the 2nd and 3rd pins of the flip-flop U2 through the resistor R22 and the other end is grounded, a key switch S1 of which one end is connected with the 1st pin of the flip-flop U2 and the other end is connected with the common end of the capacitor C15 and the resistor R22, a resistor R25 of which one end is connected with the 5th, 9th and 11th pins of the flip-flop U2, and a capacitor C31 of which one end is connected with the other end of the resistor R25 and the other end is connected with the output end of the power module; wherein the 13th pin of the flip-flop U2 is further connected with the BP / GND pin of the AD converter, and the 4th pin of the flip-flop U2 is further connected with the HOLD pin of the AD converter.

6. A hand-held humidity detector circuit according to claim 5, wherein The data transmission module connected with the high-frequency microwave module and the power module, the data transmission module comprises a communication chip U5 of ESP32F type, a switch K2 of which one end is connected with the EN pin of the communication chip U5 and the other end is grounded, a resistor R703 connected between the EN pin and the 3V3 pin of the communication chip U5, a resistor R705 connected between the SENVP pin and the 3V3 pin of the communication chip U5, a resistor R704 connected between the SENVN pin and the 3V3 pin of the communication chip U5, a resistor R710 connected between the IO34 pin and the 3V3 pin of the communication chip U5, a resistor R709 connected between the IO34 pin and the 3V3 pin of the communication chip U5, a capacitor C1 of which one end is connected with the 3V3 pin of the communication chip U5 and the other end is grounded, an electrolytic capacitor C2 of which the positive electrode is connected with the 3V3 pin of the communication chip U5 and the negative electrode is grounded, a resistor R7 of which one end is connected with the IO17 pin of the communication chip U5 and the other end is connected with the common end of the resistor R17 and the capacitor C6 in the high-frequency microwave module, a resistor R1 of which one end is connected with the IO17 pin of the communication chip U5 and the other end is connected with the output end of the power module, a resistor R8 connected between the IO17 pin and the IO16 pin of the communication chip U5, and a switch K1 of which one end is connected with the IO0 pin of the communication chip U5 and the other end is grounded.

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