CN216133129U

CN216133129U - Multifunctional digital display test pencil circuit and device thereof

Info

Publication number: CN216133129U
Application number: CN202023019898.7U
Authority: CN
Inventors: 柯元东; 黄志刚; 陈志宏; 曾繁建; 黄海林
Original assignee: ZHANGZHOU YUSHAN ELECTRONIC MANUFACTURING CO LTD
Current assignee: ZHANGZHOU YUSHAN ELECTRONIC MANUFACTURING CO LTD
Priority date: 2020-12-15
Filing date: 2020-12-15
Publication date: 2022-03-25
Anticipated expiration: 2030-12-15

Abstract

The utility model relates to a multifunctional digital display test pencil circuit and a device thereof, comprising: the alternating voltage detection circuit who contains the response pole piece, analog-to-digital conversion chip U1, button control circuit, display screen, power supply circuit, alternating voltage detection circuit electricity is connected analog-to-digital conversion chip U1, analog-to-digital conversion chip U1 electricity is connected the display screen, analog-to-digital conversion chip U1 is right alternating voltage signal handles the back, according to alternating voltage signal's intensity, controls the display screen and indicates alternating voltage signal's power, and button control circuit electricity is connected analog-to-digital conversion chip U1, button control circuit output button signal extremely analog-to-digital conversion chip U1, analog-to-digital conversion chip U1 discerns button signal and execution and the corresponding operation of this button signal, power supply circuit provides working power supply for analog-to-digital conversion chip U1. The utility model has the advantages that: the strength of the signal can be indicated and the magnetic field strength can be detected.

Description

Multifunctional digital display test pencil circuit and device thereof

Technical Field

The utility model relates to a multifunctional digital display test pencil circuit and a device thereof, belonging to the field of electricians.

Background

The inductive test pencil currently available on the market works according to the electric field induction principle. The electrified body can be measured without pulling out the wire insulating layer, thereby greatly facilitating the work of electric power operators. However, most of the existing induction test pens adopt an indicator light for displaying, the strength of the measured voltage cannot be directly displayed, and an electric power operator cannot directly know the electrification condition of an electrified body, so that certain influence is caused on safe operation.

In addition, it is more important for professional equipment maintenance and inspection personnel to grasp the operation state after the load is electrified than to judge whether the load is electrified or not. At present, whether power consumption is normal or not is generally known by testing the current condition of a load, a clamp ammeter is generally used as a commonly used test instrument, and a single power line needs to be clamped during measurement, so that great trouble is brought to measurement in narrow space or occasions where the power lines are not conveniently separated. If the direct current is tested, a clamp meter with a direct current measuring function needs to be selected, the price is relatively expensive, and if the test pencil can preliminarily know the current passing through the lead and the working current of the electrified load, the effect of achieving twice the result with half the effort can be obviously achieved.

The magnetic field is a special invisible and untouchable substance with the radiation characteristics of wave particles. A magnetic field exists around the magnets, and the interaction between the magnets is mediated by the magnetic field. Since the magnetism of a magnet is derived from an electric current, which is the movement of an electric charge, in general terms, a magnetic field is generated by the change in the moving charge or electric field. In modern science and technology and human life, magnetic fields can be encountered everywhere, and generators, motors, transformers, telegraph, telephones, induction cookers, microwave ovens, radios, accelerators, thermonuclear fusion devices and the like are not related to magnetic phenomena, the working conditions of various electrical appliances can be known by measuring the magnetic fields, stronger electromagnetic radiation is harmful to human bodies, professional magnetic field intensity testers are expensive and difficult to accept by the public, electromagnetic radiation of electric equipment and the surrounding environment can be known more by using low-price test pens, and the electromagnetic radiation is more easily popularized and utilized.

Disclosure of Invention

In order to solve the above technical problems, the present invention provides a multifunctional digital display test pencil circuit, which can measure not only an ac voltage but also a magnetic field in a non-contact manner, and can indicate the strength of a signal during measurement.

The first technical scheme of the utility model is as follows:

a multi-function digital display test pencil circuit comprising: comprises an alternating voltage detection circuit of an induction pole piece, an analog-to-digital conversion chip U1, a button control circuit, a display screen and a power supply circuit, the alternating voltage detection circuit is electrically connected with the analog-to-digital conversion chip U1, the alternating voltage detection circuit inputs the collected alternating voltage signal to the analog-to-digital conversion chip U1, the analog-to-digital conversion chip U1 is electrically connected with the display screen, after the analog-to-digital conversion chip U1 processes the alternating voltage signal, according to the intensity of the alternating voltage signal, the display screen is controlled to indicate the intensity of the alternating voltage signal, the button control circuit is electrically connected with the analog-to-digital conversion chip U1, the button control circuit outputs a button signal to the analog-to-digital conversion chip U1, the analog-to-digital conversion chip U1 recognizes the button signal and executes an operation corresponding to the button signal, and the power supply circuit supplies working power to the analog-to-digital conversion chip U1.

Preferably, the test pencil circuit further comprises a magnetic field detection circuit, the analog-to-digital conversion chip U1 provides power excitation for the magnetic field detection circuit and receives a voltage signal output by the magnetic field detection circuit, and the analog-to-digital conversion chip U1 judges the strength of the magnetic field according to the voltage signal and controls the display screen to indicate the strength of the magnetic field signal.

Preferably, the analog-to-digital conversion chip U1 includes a pin 1 and a pin 2 which form an ADC differential input, a pin 3 which can output power excitation, a pin 9 which outputs a control signal, and a signal output by the pin 9 is used for controlling the on and off of the magnetic field detection circuit; the magnetic field detection circuit comprises an NPN triode Q3, a PNP triode Q4, a voltage regulator tube DZ1, a resistor R15, a Hall element H1 and an adjustable resistor VR1, wherein the base electrode of the NPN triode Q3 is connected with a pin 9 of the analog-to-digital conversion chip U1, the collector electrode of the NPN triode Q3 is connected with the base electrode of the PNP triode Q4, the collector electrode of the PNP triode Q4 is connected with the input end of the voltage regulator tube DZ1, the emitter electrode of the PNP triode Q4 is connected with a pin 3 of the analog-to-digital conversion chip U1, the output end of the voltage regulator tube DZ1 provides a stable voltage VDD1, the output end of the voltage regulator tube DZ1 is respectively connected with a first power supply end of the Hall element H1 and one fixed end of the adjustable resistor 1, the second power supply end of the Hall element H1 is connected with a fixed end of the adjustable resistor VR1, and the second power supply end of the sliding element H1 is also connected with a pin 1 of the analog-to-digital conversion chip U1, the signal output end of the Hall element H1 is connected with a pin 2 of the analog-to-digital conversion chip U1, and the other fixed end of the adjustable resistor VR1 is grounded.

Preferably, the alternating voltage detection circuit comprises a non-contact alternating voltage induction electrode piece NCV, a resistor R1 and a resistor R4; the non-contact alternating voltage induction electrode piece NCV is connected with a pin 8 of the analog-to-digital conversion chip U1 after being connected with the resistor R4 in series, the pin 8 is a digital I/O interface, and the non-contact alternating voltage induction electrode piece NCV is also connected with the resistor R1 in series and then is grounded.

Preferably, a display screen driving module is arranged in the analog-to-digital conversion chip U1, and is connected to the display screen through a digital I/O interface on the analog-to-digital conversion chip U1, so as to drive the display screen to display information.

Preferably, the analog-to-digital conversion chip U1 is a 20-bit ADC analog-to-digital conversion chip U1, which is model number SD 8020M.

The button control circuit comprises a power switch button K1 and a function selection button K2, wherein the power switch button K1 and the function selection button K2 are respectively connected with a digital I/O interface of the analog-to-digital conversion chip U1.

Preferably, the test pencil circuit further comprises an acousto-optic alarm circuit, the power supply circuit supplies power to the acousto-optic alarm circuit, the acousto-optic alarm circuit comprises a key sensitivity indicator light LED1, an alarm indicator light LED2, a startup backlight indicator light D2, an alternating current pressure electric signal backlight indicator light D3, a buzzer BUZZ and an NPN triode Q2, one end of each of the key sensitivity indicator light LED1, the startup backlight indicator light D2 and the alternating current pressure electric signal backlight indicator light D3 is grounded, the other end is respectively connected with a digital I/O interface of the analog-to-digital conversion chip U1 in a one-to-one correspondence manner, after the alarm indicator light LED2 and the buzzer BUZZ are connected in series, one end is connected with the power supply circuit, the other end is connected with a collector of the NPN triode Q2, a base of the NPN triode Q2 is connected with the other digital I/O interface of the analog-to-digital conversion chip U1, the emitter of the NPN transistor Q2 is grounded.

Preferably, the test pencil circuit further comprises an LED lighting circuit, the power supply circuit supplies power to the LED lighting circuit, the LED lighting circuit comprises a voltage boosting chip IC1 and a lighting lamp LED3, an enable end of the voltage boosting chip IC1 is connected to a digital I/O interface of the analog-to-digital conversion chip U1, and an output end of the voltage boosting chip IC1 is connected to the lighting lamp LED3 and then grounded.

The utility model also provides a multifunctional digital display test pencil device.

A multifunctional digital display type test pencil device comprises a pencil shell and a multifunctional digital display type test pencil circuit in the first technical scheme, wherein the test pencil circuit is arranged in the pencil shell; the pen shell comprises a pen point and a pen body, the pen body comprises an operation area and a holding area, the operation area is provided with a display screen of the test pencil circuit and a button in a button control circuit, and the end part of the pen point is provided with an induction pole piece in the alternating voltage detection circuit.

The utility model has the following beneficial effects:

1. the utility model relates to a multifunctional digital display test pencil circuit and a device thereof, which adopt acousto-optic alarm and can indicate the strength of a detected signal on a display screen, for example, a plurality of progress bars are used for carrying out calibration on the alternating current voltage or the magnetic field to be tested, so that a tester can quickly and accurately judge the strength of the signal, and the effect of getting twice the result with half the effort is achieved.

2. The multifunctional digital display test pencil circuit and the device thereof have high and low sensitivity which can be selected, can cover a larger measurement range and meet the test requirements of different occasions.

3. The multifunctional digital display test pencil circuit and the device thereof can increase the magnetic field detection function of the product only by adding a small number of devices, and have higher cost performance.

4. The utility model relates to a multifunctional digital display test pencil circuit and a device thereof.A (SD8020M) 20-bit ADC analog-to-digital conversion chip U1 is selected, an LCD driving module is provided, and an ADC differential input end and an analog signal input end of an ADC are provided, so that the test requirements of alternating voltage and a magnetic field can be met simultaneously, and the circuit is simple and can easily achieve the expected effect.

Drawings

FIG. 1 is a schematic block diagram of the multifunctional digital display test pencil circuit of the present invention;

FIG. 2 is a schematic circuit diagram of a multifunctional digital display test pencil circuit of the present invention;

FIG. 3 is a schematic diagram of a magnetic field detection circuit of the multifunctional digital display test pencil circuit of the present invention;

FIG. 4 is a schematic diagram of an audible and visual alarm circuit of the multifunctional digital display test pencil circuit of the present invention;

FIG. 5 is a schematic diagram of an LED lighting circuit of the multifunctional digital display test pencil circuit of the present invention;

FIG. 6 is a diagram showing the display effect of the display screen of the multifunctional digital test pencil circuit according to the present invention.

Fig. 7 is a top view of a product structure of a multifunctional digital display test pencil device of the present invention.

Detailed Description

The utility model is described in detail below with reference to the figures and the specific embodiments.

Example one

Referring to fig. 1, a multifunctional digital display test pencil circuit includes: comprises an alternating voltage detection circuit of an induction pole piece, an analog-to-digital conversion chip U1, a button control circuit, a display screen and a power supply circuit, the alternating voltage detection circuit is electrically connected with the analog-to-digital conversion chip U1, the alternating voltage detection circuit inputs the collected alternating voltage signal to the analog-to-digital conversion chip U1, the analog-to-digital conversion chip U1 is electrically connected with the display screen, after the analog-to-digital conversion chip U1 processes the alternating voltage signal, according to the intensity of the alternating voltage signal, the display screen is controlled to indicate the intensity of the alternating voltage signal, the button control circuit is electrically connected with the analog-to-digital conversion chip U1, the button control circuit outputs a button signal to the analog-to-digital conversion chip U1, the analog-to-digital conversion chip U1 recognizes the button signal and executes an operation corresponding to the button signal, and the power supply circuit supplies working power to the analog-to-digital conversion chip U1. Preferably, the display screen is an LCD (liquid crystal display) screen.

The test pencil circuit can realize the purpose of indicating the strength of alternating voltage through the display screen, so that a tester can make quick and accurate judgment on the signal strength, and the effect of achieving twice the result with half the effort is achieved

The implementation process of the present invention is specifically described by taking the 20-bit ADC analog-to-digital conversion chip SD8020M as an example.

Referring to fig. 2, an LCD driver module is disposed in the analog-to-digital conversion chip U1, pin 1 of the analog-to-digital conversion chip U1 is AIP, pin 2 is AIN, which form an ADC differential input terminal, pin 3 of the analog-to-digital conversion chip U1 is AVVDDR, which can provide power excitation for an external sensor, pin 6 of the analog-to-digital conversion chip U1 is digital I/O P20, which can be used as an external interrupt 0, pin 7 of the analog-to-digital conversion chip U1 is digital I/O P21, which can be used as an external interrupt 1, pin 8 of the analog-to-digital conversion chip U1 is digital I/O P22, which can be combined with a negative terminal V-of a power supply circuit to be used as an analog signal input or a reference voltage input of an ADC and also used for an external voltage detection input, pin 9 of the analog-to-digital conversion chip U1 is digital I/O P23, pin 15 of the analog-to-digital conversion chip U1 is digital I/O P25, the digital-to-analog conversion chip U3878 can be used as buzzer output, pins 16 to 27 of the analog-to-digital conversion chip U1 are digital I/O P47-40, P37-34 can be used as SEG11-0 of a liquid crystal display screen, pins 28 to 31 of the analog-to-digital conversion chip U1 are digital I/O P33-30, and the digital-to-analog conversion chip U1 can be used as COM3-0 of the liquid crystal display screen.

In this embodiment, as shown in fig. 2, the power supply circuit is a battery BATT, and 2 pieces of 1.5V batteries can be used to supply power to the product, and the negative terminal V-of the battery BATT is used as a ground terminal and also as a common ground terminal. The positive electrode of the battery BATT is used as a power supply VDD and is connected with a pin 5 of a pin 4 boosting chip IC1 of an analog-to-digital conversion chip U1, when the product is not operated for 5 minutes, the product can be automatically shut down, and the product enters a sleep mode so as to save working power.

As shown in fig. 2, the ac voltage detection circuit includes a non-contact ac voltage sensing electrode piece NCV, a resistor R1 and a resistor R4; the non-contact alternating voltage induction electrode piece NCV is connected with a pin 8 of the analog-to-digital conversion chip U1 after being connected with the resistor R4 in series, the pin 8 is a digital I/O interface, and the non-contact alternating voltage induction electrode piece NCV is also connected with the resistor R1 in series and then is grounded. The non-contact alternating voltage induction electrode plate can be composed of a nickel-plated brass plate. The resistor R1 can be used for testing sensitivity adjustment, and the larger the resistance value of R1, the higher the sensitivity.

A magnetic field detection circuit can be added in the test pencil circuit, so that the test pencil has a magnetic field detection function, and the strength of a magnetic field is indicated through a display screen. The analog-to-digital conversion chip U1 provides power excitation for the magnetic field detection circuit and receives voltage signals output by the magnetic field detection circuit, and the analog-to-digital conversion chip U1 judges the strength of a magnetic field according to the voltage signals and controls the display screen to indicate the strength of the magnetic field signals. As shown in fig. 3, the pin 9 of the analog-to-digital conversion chip U1 is used for outputting a control signal to control the on and off of the magnetic field detection circuit; the magnetic field detection circuit comprises an NPN triode Q3, a PNP triode Q4, a voltage regulator tube DZ1, a resistor R15, a Hall element H1 and an adjustable resistor VR1, wherein in the embodiment, the Hall element H1 is HW-108A. The base of the NPN triode Q3 is connected to the pin 9 of the analog-to-digital conversion chip U1, the collector of the NPN triode Q3 is connected to the base of the PNP triode Q4, the collector of the PNP triode Q4 is connected to the input end of the regulator DZ1, the emitter of the PNP triode Q4 is connected to the pin 3 of the analog-to-digital conversion chip U1, the output end of the regulator DZ1 provides a stable voltage VDD1, the output end of the regulator DZ1 is respectively connected to the first power supply end of the hall element H1 (i.e., the pin 1 of the hall element H1 in fig. 3) and a fixed end of the adjustable resistor VR1, the second power supply end of the hall element H1 (i.e., the pin 4 of the hall element H1 in fig. 3) is connected to the sliding end of the adjustable resistor VR1, the second power supply end of the hall element H1 is further connected to the pin 1 of the analog-to-digital conversion chip U1, and the signal output end of the hall element H5 (i.e, i.e., the pin 5732 of the hall element H1 in fig. 3) is connected to the pin 582 of the pin 1 of the analog-to-digital conversion chip U1 And the other fixed end of the adjustable resistor VR1 is grounded. In fig. 3, a biasing resistor R13 is connected in series with the base of the NPN transistor Q3, a biasing resistor R14 is connected in series with the base of the PNP transistor Q4, and a filter capacitor C4 is connected in series with the output end of the regulator DZ1 and then grounded. A resistor R15 is connected in series with the first power supply terminal of the hall element H1, and resistors R18, R17 and R16 are connected in series with the two fixed terminals and the sliding terminal of the adjustable resistor VR1, so that the voltage values at the pin 1 and the pin 3 of the hall element H1 meet the design requirements, which is a conventional technical means in the field, and other resistor combination design methods are also adopted to meet the electrical requirements of the hall element H1 or to arrange the circuit design requirements. When the test pencil selects a magnetic field measurement mode, a pin 9 of the analog-to-digital conversion chip U1 outputs a high level, a pin 3 of the analog-to-digital conversion chip U1 outputs a voltage of 2.4V, the voltage is stabilized by a voltage stabilizing tube DZ1, a stable working voltage is provided for the Hall element H1, and according to a magnetic field generated by a lead with current, the magnetic field intensity generated is in direct proportion to the current and in inverse proportion to the distance, the formula is as follows: and B is KI/d, wherein: b is the magnetic field intensity; k is a known coefficient; i is the current intensity; d is the distance to the straight wire. Hall Effect principle: when a conductor is placed in a magnetic field, which is perpendicular to the direction of the current, a transverse potential difference VH is generated in the conductor, perpendicular to the direction of the magnetic field and the direction of the current. The Hall element is utilized to test the induced magnetic field intensity, and the Hall element has unequal potential which can influence the measurement result, so that the unequal potential needs to be compensated. When VR1 is adjusted to make B equal to 0, VH equal to 0, and Hall element H1 is HW-108A, when magnetic field strength B equal to 50mT, and supply voltage Vc of Hall equal to 1V, output voltage VH of Hall element can be as high as 320mV, and weak magnetic field strength can be ensured to be measured normally when high sensitivity measurement is selected.

As shown in fig. 2, the button control circuit includes a power switch button K1 and a function selection button K2, and the power switch button K1 and the function selection button K2 are respectively connected to a digital I/O interface of the analog-to-digital conversion chip U1. Specifically, one end of a power switch button K1 is connected with a pin 6 of an analog-to-digital conversion chip U1, the other end of the power switch button is grounded, the power switch button K1 is used for being used as a power supply and buzzer warning sound switch, the power supply is turned on or off after long pressing for 2 seconds, and the buzzer warning sound and warning indicator lamp are turned on or off after short pressing, one end of a function selection button K2 is connected with a pin 7 of the analog-to-digital conversion chip U1, and the other end of the function selection button K2 is connected with the ground and is used for selecting high and low sensitivity and alternating voltage or magnetic field measurement functions.

The test pencil circuit further comprises an acousto-optic alarm circuit, and the power supply circuit supplies power to the acousto-optic alarm circuit. As shown in fig. 4, the acousto-optic warning circuit includes a key sensitivity indicator LED1, a warning indicator LED2, a startup backlight indicator D2, an ac voltage electric signal backlight indicator D3, a buzzer BUZZ, and an NPN triode Q2, wherein one ends of the key sensitivity indicator LED1, the startup backlight indicator D2, and the ac voltage electric signal backlight indicator D3 are all grounded, the other ends are respectively connected to a digital I/O interface of the analog-to-digital conversion chip U1 in a one-to-one correspondence manner, after the warning indicator LED2 and the buzzer BUZZ are connected in series, one end is connected to the power supply circuit, the other end is connected to a collector of the NPN triode Q2, a base of the NPN triode Q2 is connected to another digital I/O interface of the analog-to-digital conversion chip U1, and an emitter of the NPN triode Q2 is grounded. Specifically, a pin 15 of the analog-to-digital conversion chip U1 is connected to a resistor R9, the other end of the resistor R9 is connected to a base of an NPN transistor Q2, a collector of the NPN transistor Q2 is connected to one pin of a buzzer BUZZ and a cathode of an alarm indicator light LED2, the other pin of the buzzer BUZZ is connected to a resistor R10, the other pin of the resistor R10 is connected to a power supply VDD (positive electrode of a power supply battery), an emitter of the NPN transistor Q2 is grounded, an anode of the alarm indicator light LED2 is connected to the resistor R12, the other pin of the resistor R12 is connected to the power supply VDD, a pin 18 of the analog-to-digital conversion chip is connected to one end of the resistor R6, the other end of the resistor R6 is connected to an anode of a key sensitivity indicator light LED1, a cathode of the key sensitivity indicator light LED1 is grounded, a pin 17 of the analog-to-digital conversion chip U1 is connected to one end of the resistor R7, and the other end of the key-on resistor R7 is connected to a backlight D2, the cathode of the power-on backlight indicator light D2 is grounded, and the power-on backlight indicator light D2 is generally green. The pin 16 of the analog-to-digital conversion chip U1 is connected with one end of a resistor R8, the other end of the resistor R8 is connected with the anode of the alternating-current pressure electric signal backlight indicator lamp D3, and the cathode of the alternating-current pressure electric signal backlight indicator lamp D3 is grounded. The alternating current pressure electrical signal backlight indicator light D3 is typically red. When the test pencil detects an alternating voltage, the flashing speed of the red warning signal lamp LED2 is increased or decreased along with the intensity of the sensed voltage signal, the beep prompt tone of the buzzer is synchronously increased or decreased, when the test pencil detects a static magnetic field, the red warning signal lamp LED2 lights up, the buzzer sounds long, when a dynamic magnetic field is detected, the red warning signal lamp LED2 lights up and the buzzer sounds intermittently, when a current test is carried out, whether the current component is a direct current component or an alternating current component is judged, the green starting backlight indicator lamp D2 lights up when the test pencil is started, and when the test pencil senses a strong enough alternating voltage signal, the backlight changes from green to red, namely the alternating current pressure electric signal backlight indicator lamp D3 lights up, and the green starting backlight indicator lamp D2 lights up.

The test pencil circuit also comprises an LED lighting circuit, the power supply circuit supplies power to the LED lighting circuit, the LED lighting circuit comprises a boosting chip IC1 and a lighting lamp LED3, the enabling end of the boosting chip IC1 is connected with a digital I/O interface of the analog-to-digital conversion chip U1, and the output end of the boosting chip IC1 is connected with the rear ground of the lighting lamp LED 3. Specifically, as shown in fig. 5, pin 19 of the analog-to-digital conversion chip U1 is connected to pin 3 of the resistor R20 and the boost chip IC1 (charge pump boost DC-DC converter), respectively, the other end of the resistor R20 is grounded, pin 5 of the boost chip IC1 is connected to the power supply VDD, and pin 2 of the boost chip IC1 is grounded. Pin 4 of the boost chip IC1 is connected to one end of a capacitor C7, pin 6 of the boost chip IC1 is connected to the other end of the capacitor C7, pin 1 of the boost chip IC1 outputs a voltage of 3.3V, which is connected to one end of a capacitor C6 and one end of a resistor R11, respectively, the other end of the capacitor C6 is grounded, the other end of the resistor R11 is connected to the anode of the LED lighting LED3, and the cathode of the lighting LED3 is grounded.

The display symbols of the display screen are shown in fig. 6, the display screen displays a LOW symbol when LOW-sensitivity measurement is selected, the display screen displays an HiS symbol when high-sensitivity measurement is selected, the display screen displays an AC symbol when alternating voltage measurement is selected, and the display screen displays the AC symbols simultaneously when the detected alternating voltage strength is strong enough

And (4) a symbol. When the magnetic field measurement is selected, the display screen displays the MSD symbol, and when the buzzer alarm function is on, the display screen displays

When the symbol, the buzzer and the warning lamp are turned off,

the symbol is not displayed, the power consumption of the battery can be saved, the service life is prolonged, and the function can be selected when the battery is near to be exhausted and cannot be replaced in time. Meanwhile, the display screen indicates the detected signal strength with 8 progress bars (the stronger the signal, the more the progress bars).

Example two

As shown in fig. 7, a multifunctional digital display test pencil device comprises a pencil shell and a multifunctional digital display test pencil circuit according to the first embodiment, the test pencil circuit is disposed in the pencil shell 1, the pencil shell 1 comprises a pencil point 11 and a pencil body 12, the pencil body 12 comprises an operation area 121 and a holding area 122, the operation area 121 is provided with a display screen 3 of the test pencil circuit and a button 4 in a button control circuit, and the end of the pencil point 11 is provided with an induction pole piece 5 in an alternating voltage detection circuit.

The multifunctional digital display test pencil circuit and the device thereof can detect the strength of alternating current signals and the strength of magnetic fields, adopt acousto-optic alarm and can indicate the strength of the detected signals on the display screen, and a tester can quickly and accurately judge the strength of the detected signals to achieve the effect of twice the result with half the effort. Meanwhile, the test pencil of the utility model has selectable high and low sensitivity, can cover a larger measurement range and meets the test requirements of different occasions.

The above description is only an embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications of equivalent structures and equivalent processes performed by the present specification and drawings, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.

Claims

1. A multi-functional digital display test pencil circuit, comprising: comprises an alternating voltage detection circuit of an induction pole piece, an analog-to-digital conversion chip U1, a button control circuit, a display screen and a power supply circuit, the alternating voltage detection circuit is electrically connected with the analog-to-digital conversion chip U1, the alternating voltage detection circuit inputs the collected alternating voltage signal to the analog-to-digital conversion chip U1, the analog-to-digital conversion chip U1 is electrically connected with the display screen, after the analog-to-digital conversion chip U1 processes the alternating voltage signal, according to the intensity of the alternating voltage signal, the display screen is controlled to indicate the intensity of the alternating voltage signal, the button control circuit is electrically connected with the analog-to-digital conversion chip U1, the button control circuit outputs a button signal to the analog-to-digital conversion chip U1, the analog-to-digital conversion chip U1 recognizes the button signal and executes an operation corresponding to the button signal, and the power supply circuit provides working power for the analog-to-digital conversion chip U1; the magnetic field detection circuit further comprises a magnetic field detection circuit, the analog-to-digital conversion chip U1 provides power excitation for the magnetic field detection circuit and receives voltage signals output by the magnetic field detection circuit, and the analog-to-digital conversion chip U1 judges the strength of a magnetic field according to the voltage signals and controls the display screen to indicate the strength of the magnetic field signals.

2. The multifunctional digital display test pencil circuit of claim 1, wherein: the analog-to-digital conversion chip U1 comprises a pin 1 and a pin 2 which form ADC differential input, a pin 3 which can output power excitation, and a pin 9 which outputs a control signal, wherein the signal output by the pin 9 is used for controlling the on and off of the magnetic field detection circuit; the magnetic field detection circuit comprises an NPN triode Q3, a PNP triode Q4, a voltage regulator tube DZ1, a resistor R15, a Hall element H1 and an adjustable resistor VR1, wherein the base electrode of the NPN triode Q3 is connected with a pin 9 of the analog-to-digital conversion chip U1, the collector electrode of the NPN triode Q3 is connected with the base electrode of the PNP triode Q4, the collector electrode of the PNP triode Q4 is connected with the input end of the voltage regulator tube DZ1, the emitter electrode of the PNP triode Q4 is connected with a pin 3 of the analog-to-digital conversion chip U1, the output end of the voltage regulator tube DZ1 provides a stable voltage VDD1, the output end of the voltage regulator tube DZ1 is respectively connected with a first power supply end of the Hall element H1 and one fixed end of the adjustable resistor 1, the second power supply end of the Hall element H1 is connected with a fixed end of the adjustable resistor VR1, and the second power supply end of the sliding element H1 is also connected with a pin 1 of the analog-to-digital conversion chip U1, the signal output end of the Hall element H1 is connected with a pin 2 of the analog-to-digital conversion chip U1, and the other fixed end of the adjustable resistor VR1 is grounded.

3. The multifunctional digital display test pencil circuit of claim 1, wherein: the alternating voltage detection circuit comprises a non-contact alternating voltage induction electrode piece NCV, a resistor R1 and a resistor R4; the non-contact alternating voltage induction electrode piece NCV is connected with a pin 8 of the analog-to-digital conversion chip U1 after being connected with the resistor R4 in series, the pin 8 is a digital I/O interface, and the non-contact alternating voltage induction electrode piece NCV is also connected with the resistor R1 in series and then is grounded.

4. The multifunctional digital display test pencil circuit of claim 1, wherein: a display screen driving module is arranged in the analog-to-digital conversion chip U1 and is connected with the display screen through a digital I/O interface on the analog-to-digital conversion chip U1 to drive the display screen to display information.

5. The multifunctional digital display test pencil circuit of claim 1, wherein: the analog-to-digital conversion chip U1 is a 20-bit ADC analog-to-digital conversion chip U1, and the model thereof is SD 8020M.

6. The multifunctional digital display test pencil circuit of claim 1, wherein: the button control circuit comprises a power switch button K1 and a function selection button K2, wherein the power switch button K1 and the function selection button K2 are respectively connected with a digital I/O interface of the analog-to-digital conversion chip U1.

7. The multifunctional digital display test pencil circuit of claim 1, wherein: the alarm circuit comprises a key sensitivity indicator LED1, an alarm indicator LED2, a startup backlight indicator D2, an alternating current pressure electric signal backlight indicator D3, a buzzer BUZZ and an NPN triode Q2, one ends of the key sensitivity indicator light LED1, the starting backlight indicator light D2 and the alternating current pressure electric signal backlight indicator light D3 are all grounded, the other ends are respectively connected with a digital I/O interface of the analog-to-digital conversion chip U1 in a one-to-one correspondence manner, after the alarm indicator light LED2 is connected with the buzzer BUZZ in series, one end of the alarm indicator light LED2 is connected with the power supply circuit, the other end of the alarm indicator light LED2 is connected with the collector of the NPN triode Q2, the base electrode of the NPN triode Q2 is connected with the other digital I/O interface of the analog-to-digital conversion chip U1, and the emitter electrode of the NPN triode Q2 is grounded.

8. The multifunctional digital display test pencil circuit of claim 1, wherein: still include the LED lighting circuit, the power supply circuit is the power supply of LED lighting circuit, the LED lighting circuit includes a chip IC1 and light LED3 steps up, the enable end of chip IC1 that steps up connects a digital I/O interface of analog-to-digital conversion chip U1, the output of chip IC1 that steps up is connected ground connection behind the light LED 3.

9. The utility model provides a multi-functional digital display test pencil device which characterized in that: the multifunctional digital display type test pencil circuit comprises a pencil shell and the multifunctional digital display type test pencil circuit as claimed in any one of claims 1 to 8, wherein the test pencil circuit is arranged in the pencil shell, the pencil shell comprises a pencil head and a pencil body, the pencil body comprises an operation area and a holding area, the operation area is provided with a display screen of the test pencil circuit and a button in a button control circuit, and the end part of the pencil head is provided with an induction pole piece in the alternating voltage detection circuit.