CN109581022A - Double-impedance input universal meter and method for displaying battery capacity on universal meter - Google Patents
Double-impedance input universal meter and method for displaying battery capacity on universal meter Download PDFInfo
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- CN109581022A CN109581022A CN201910087116.6A CN201910087116A CN109581022A CN 109581022 A CN109581022 A CN 109581022A CN 201910087116 A CN201910087116 A CN 201910087116A CN 109581022 A CN109581022 A CN 109581022A
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- 238000012545 processing Methods 0.000 claims description 29
- 238000006243 chemical reaction Methods 0.000 claims description 15
- 238000012544 monitoring process Methods 0.000 claims description 9
- 230000005611 electricity Effects 0.000 claims description 2
- 229910052751 metal Inorganic materials 0.000 description 40
- 239000002184 metal Substances 0.000 description 40
- 238000005259 measurement Methods 0.000 description 19
- 101000974343 Homo sapiens Nuclear receptor coactivator 4 Proteins 0.000 description 15
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- 102100028680 Protein patched homolog 1 Human genes 0.000 description 13
- 101710161390 Protein patched homolog 1 Proteins 0.000 description 13
- 238000012360 testing method Methods 0.000 description 11
- 102100036894 Protein patched homolog 2 Human genes 0.000 description 10
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- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 4
- 229910001416 lithium ion Inorganic materials 0.000 description 4
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- WJZHMLNIAZSFDO-UHFFFAOYSA-N manganese zinc Chemical compound [Mn].[Zn] WJZHMLNIAZSFDO-UHFFFAOYSA-N 0.000 description 3
- 101100410162 Caenorhabditis elegans ptc-3 gene Proteins 0.000 description 2
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- 101100522123 Caenorhabditis elegans ptc-1 gene Proteins 0.000 description 1
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 1
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 1
- 208000027418 Wounds and injury Diseases 0.000 description 1
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- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 1
- 239000010931 gold Substances 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- 208000014674 injury Diseases 0.000 description 1
- 229910052744 lithium Inorganic materials 0.000 description 1
- KBMLJKBBKGNETC-UHFFFAOYSA-N magnesium manganese Chemical compound [Mg].[Mn] KBMLJKBBKGNETC-UHFFFAOYSA-N 0.000 description 1
- 229910052748 manganese Inorganic materials 0.000 description 1
- 239000011572 manganese Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- YVUZUKYBUMROPQ-UHFFFAOYSA-N mercury zinc Chemical compound [Zn].[Hg] YVUZUKYBUMROPQ-UHFFFAOYSA-N 0.000 description 1
- BSWGGJHLVUUXTL-UHFFFAOYSA-N silver zinc Chemical compound [Zn].[Ag] BSWGGJHLVUUXTL-UHFFFAOYSA-N 0.000 description 1
- 238000013024 troubleshooting Methods 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
- G01R15/12—Circuits for multi-testers, i.e. multimeters, e.g. for measuring voltage, current, or impedance at will
- G01R15/125—Circuits for multi-testers, i.e. multimeters, e.g. for measuring voltage, current, or impedance at will for digital multimeters
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Abstract
The invention relates to a double-impedance input multimeter which comprises an input terminal, a gear selector switch, a power supply circuit, a double-impedance measuring circuit, an ADC (analog to digital converter), a DSP (digital signal processor) and an LCD (liquid crystal display) screen, wherein the input terminal is connected with the power supply circuit; the gear selector switch is used for switching the measuring range of the multimeter; the power supply circuit provides working voltage for the multimeter; the dual impedance measurement circuit transmits the electrical signal measured by the input terminal to the ADC converter; the output end of the ADC converter is electrically connected with the input end of the DSP, and the ADC converter converts an input electric signal into a digital signal and transmits the digital signal to the DSP; the output end of the DSP is electrically connected with the LCD display screen, and the DSP converts digital signals into driving signals of the LCD display screen to drive the LCD display screen to display corresponding data.
Description
Technical Field
The invention relates to a double-impedance input universal meter and a method for displaying the electric quantity of a battery on the universal meter, and relates to the technical field of digital universal meters.
Background
The voltage measurement of the digital multimeter has the characteristic of high input impedance, basically 10M omega, and some small meters with manual range shifting adopt 1M omega, which means that when the digital multimeter is placed in a circuit for measurement, the influence on the circuit performance is extremely small, which is the effect required by most voltage measurement applications, however, some circuits sensitive to electromagnetic field interference or circuits with short distance between electrified wires and non-electrified wires exist in the measurement, because distributed capacitance exists between the wires, when the multimeter with high impedance is used for measurement, a false voltage is coupled to a measured instrument through the distributed capacitance, so that a false reading is obtained, the false voltage can reach 80-85% of the voltage of 'hard wiring', if the false voltage is not identified as the false voltage, extra time and energy are consumed in the troubleshooting of the circuit fault, if a low impedance measuring gear with input impedance of only 1K to dozens of K omega is arranged, the false voltage disappears, the digital multimeter can meet the requirements of basic voltage measurement, and the digital multimeter can hardly buy a single product with high price.
The digital multimeter is taken as a common electrical measuring instrument, is a common thing when being carried to outdoor or field operation, and is a very troublesome thing when a tester finds that the power consumption of a power supply battery of the instrument is about to be exhausted or exhausted and no battery which can be replaced is available, a plurality of products have the advantages that when the power consumption of the power supply battery is low, some test functions have low power consumption and can be normally used, while some functions have high power consumption, such as back lighting, when a buzzer gives an alarm, the residual power of the power supply battery is seriously insufficient and cannot be normally used, all digital multimeters in the market at present adopt a low-voltage prompt symbol on an LCD only when the power consumption of the battery is about to be exhausted, inconvenience is avoided for normal use of a user, and the invention is necessary for monitoring the power consumption of the power supply battery of the instrument in real time.
The battery is used as a mode for providing energy sources for various electrical products, is widely applied and has various varieties, common batteries are divided into 1.5V,3.0V,3.7V,6V,9V,12V,24V and the like according to voltage specifications, disposable batteries and rechargeable batteries are divided according to whether rechargeable or not, and common disposable batteries comprise alkaline manganese batteries, zinc-manganese batteries, lithium batteries, silver-zinc batteries, zinc-air batteries, zinc-mercury batteries and magnesium-manganese batteries; the conventional product has more defects and defects in the aspect of battery test function, the conventional product is a digital meter with manual range conversion basically, some batteries (such as 1.5V,9V and 12V batteries) are provided with a digital meter according to specific gears, a resistor with a certain resistance value is used as a dummy load (namely a discharge resistor) for simulating and testing the voltage of the battery in a working state, due to the variety of the batteries, the problem that only a plurality of batteries with voltage specifications can be tested has larger limitation and cannot meet the test requirement (such as 3.7V lithium ion batteries commonly used on mobile phones are excluded), due to the fact that the sizes of the batteries have more differences, if only one working current is set for the tested battery, the possibility of the difference from the actual working condition exists, the test result is difficult to ensure the accuracy of the test result, the problem that the tested battery has enough working current and can not be tested by using a conventional 3.7V lithium ion battery, and if the tested battery has a certain false input resistance value is set as a false fuse, the conventional product has a great risk of being input resistor, such as a false fuse: the UT33B + product specification notes the following remarks in the battery measurement section: the voltage higher than 60V of direct current or 30V of alternating current is not required to be input, so that the damage to an instrument or the injury to a user are avoided, and the safety has a great problem due to the protection mode. For testers, paying attention to the working voltage of a tested battery, paying more attention to the actual capacity of the tested battery, using 3 LED lamps at most in a digital table with a function of measuring the battery on the market, prompting the states of the tested battery by using 'good', 'problematic' and 'bad' according to the voltage of the tested battery, wherein in addition to the problems, the states are only distinguished by 3, and the LED lamps occupy more positions, as shown in a structural schematic diagram of a product capable of measuring the voltage of the battery in fig. 1, so that the problems exist;
as shown in fig. 2, there is also a method and a meter for monitoring the battery power in a multi-state, in which a discharge resistance of 30 Ω is used for a battery test of 1.5V, a discharge resistance of 900 Ω is used for a battery test of 9V, and a resistance of 240 Ω is used for a battery test of 12V. The problems of limitation, accuracy and safety cannot be avoided, the only difference is that the indication of the electric quantity of the battery measured by the LED lamp is changed into LCD display, and the display modes of the LCD are respectively expressed by 3 English words as follows: "GOOD", "LOW", or "Bad"; "GOOD", "LOW" and "Bad". These words occupy more visible area of the LCD, necessarily affecting the display effect of other physical quantity measurements, and then take a 12V battery measurement as an example: the load resistor 240 omega has a discharge current of 12/240=0.05A according to ohm's theorem, and it is known that a 12V battery is commonly used in a rechargeable storage battery with a larger capacity, and the voltage value changes due to the magnitude of the discharge current under the condition of the same residual capacity, the higher the discharge current is, the lower the voltage is, the discharge current is above 7A when the electric vehicle normally runs, the discharge current of 0.05A is like no load, and the actual voltage is 13.7V when the single battery is fully charged and no load, but is not nominal 12V. The non-linear relation exists between the voltage and the capacity of the battery, when the battery is discharged to a certain voltage value, the voltage can be sharply reduced, and if the battery is deeply discharged for a long time, the damage to the battery is quite large; therefore, the discharge must be terminated at a certain voltage value, and the voltage for terminating the discharge is called a discharge termination voltage; the set discharge end voltage is significant for prolonging the service life of the storage battery, the discharge end voltage of a normal 12V rechargeable battery is 10.5V, the discharge resistance adopts a resistance of 240 omega according to the test of the 12V battery set by the patent and related products, the battery voltage is more than or equal to 10.5V and shows GOOD, and the battery voltage is less than or equal to 7.5 and shows Bad. Obviously, the method is unscientific and unreasonable, and is easy to cause misdetection and misjudgment. Therefore, it is necessary to make more optional settings for the discharge current of the battery and to make finer scales for the battery capacity.
Disclosure of Invention
In order to solve the problems in the prior art, the invention provides a double-impedance input multimeter and a method for displaying the battery capacity on the multimeter.
The technical scheme of the invention is as follows:
the first technical scheme is as follows:
a double-impedance input multimeter comprises an input terminal, a gear shift switch, a power supply circuit, a double-impedance measurement circuit, an ADC converter, a DSP digital processor and an LCD display screen; the gear selector switch is used for switching the measuring range of the multimeter; the power supply circuit comprises a battery and provides working voltage for the multimeter; the double-impedance measuring circuit comprises a high-input impedance circuit and a low-input impedance circuit, wherein the input end of the high-input impedance circuit is electrically connected with the input terminal, the output end of the high-input impedance circuit is electrically connected with the ADC through a gear selector switch, the input end of the low-input impedance circuit is electrically connected with the input terminal, the output end of the low-input impedance circuit is electrically connected with the ADC through the gear selector switch, and the double-impedance measuring circuit transmits an electric signal measured by the input terminal to the ADC; the output end of the ADC converter is electrically connected with the input end of the DSP, and the ADC converter converts an input electric signal into a digital signal and transmits the digital signal to the DSP; the output end of the DSP is electrically connected with the LCD display screen, and the DSP converts digital signals into driving signals of the LCD display screen to drive the LCD display screen to display corresponding data.
Furthermore, the gear shift switch comprises a plurality of groups of golden finger contact pieces.
Further, the high input impedance circuit includes a high resistance resistor, one end of the high resistance resistor is electrically connected to the input terminal, and the other end of the high resistance resistor is electrically connected to the input terminal of the ADC converter; the low input impedance circuit comprises a plurality of low-resistance resistors with different resistances, one end of each low-resistance resistor is electrically connected with the input terminal, the other end of each low-resistance resistor is electrically connected with each group of golden finger contact pieces on the gear shift switch, and after one group of golden finger contact pieces are connected, the corresponding low-resistance resistors are connected with the high-resistance resistors in parallel.
Furthermore, the power supply circuit comprises a voltage-stabilizing power supply chip, the input end of the voltage-stabilizing power supply chip is connected with the anode of the battery through a group of golden finger contact pieces, the grounding end of the voltage-stabilizing power supply chip is connected with the cathode of the battery, and the output end of the voltage-stabilizing power supply chip provides working voltage for electrical appliances in the multimeter.
The battery power monitoring circuit further comprises a battery power monitoring circuit, wherein the battery power monitoring circuit comprises a voltage-dividing resistor R4 and a voltage-dividing resistor R20, one end of the voltage-dividing resistor R4 is connected with the input end of the voltage-stabilizing power supply chip, the other end of the voltage-dividing resistor R4 is connected with one end of the voltage-dividing resistor R20, and the other end of the voltage-dividing resistor R20 is connected with the grounding end of the voltage-stabilizing power supply chip; the joint of connecting divider resistance R4 and divider resistance R20 is connected with the input electricity of ADC converter, transmits battery voltage signal to it, the ADC converter carries to after converting battery voltage signal into digital signal DSP digital processor, DSP digital processor drive LCD display screen display battery electric quantity.
Further, the ADC converter and the DSP are integrated into a universal meter automatic range conversion chip IC 1.
The second technical scheme is as follows:
a method of displaying battery power on a multimeter comprising the steps of:
pre-writing the relation between the voltage value of each specification battery and the battery electric quantity in a processing chip of the universal meter;
selecting a measuring range on a universal meter according to the nominal voltage of the battery to be measured;
detecting the voltage value of the battery to be detected, and sending the voltage value to a processing chip of the universal meter;
the processing chip of the universal meter converts the voltage value of the battery to be tested into the battery capacity of the current battery to be tested according to the voltage value of the battery to be tested, and drives a display screen of the universal meter to display corresponding data;
the battery to be tested can be a battery detected on an input terminal of the universal meter or a power supply battery of the universal meter.
Further, the specific method for pre-writing the relationship between the voltage value of each specification battery and the battery capacity in the processing chip of the multimeter comprises the following steps:
acquiring a discharge curve of each specification of battery according to the discharge resistance of each specification of battery in the universal meter;
according to the corresponding battery discharge curve, the electric quantity of each specification battery is divided into a plurality of equal parts, and the maximum voltage value and the minimum voltage value of each equal division interval are obtained;
and according to the maximum voltage value and the minimum voltage value of each equal division interval, the battery electric quantity of the battery with the corresponding specification is graduated and written into a processing chip of the universal meter.
Furthermore, the specific method for converting the processing chip of the multimeter into the battery capacity of the current battery to be tested according to the voltage value of the battery to be tested and driving the display screen of the multimeter to display the corresponding data is as follows:
comparing the voltage value of the battery to be measured with the scale of the battery with the corresponding specification, and dividing the voltage value into corresponding equal division intervals;
and a processing chip of the multimeter drives a display screen to display corresponding battery electric quantity data according to the battery electric quantity corresponding to the equal division interval into which the voltage value of the battery to be tested is divided.
Further, the battery electric quantity data is displayed in a progress bar mode; each equal interval corresponds to different progresses of the progress bar, and the processing chip of the universal meter drives the progress bar on the display screen to display the corresponding progress according to the corresponding equal interval.
The invention has the following beneficial effects:
1. the invention relates to a double-impedance input multimeter which is provided with a high input impedance circuit and a low input impedance circuit, and is connected with an ADC (analog to digital converter) through a gear change-over switch, so that the problem that the measurement requirement of the multimeter cannot be met only by setting high input impedance in the prior art is solved.
2. The invention discloses a double-impedance input universal meter which is provided with a battery capacity monitoring circuit and can monitor the battery capacity of the universal meter.
3. The invention relates to a double-impedance input universal meter, wherein a low-input impedance circuit is provided with a plurality of low-impedance resistors with different resistance values so as to adapt to various objects to be measured with different specifications, and the measurement result is more accurate.
4. According to the method for displaying the battery capacity on the universal meter, the relation between the battery voltage and the battery capacity is written into the universal meter processing chip in advance, so that the residual capacity of the battery to be tested can be obtained by measuring the voltage of the battery to be tested, corresponding data is displayed through the display screen of the universal meter, and the obtained battery capacity is relatively accurate.
5. According to the method for displaying the electric quantity of the battery on the multimeter, the electric quantity of the battery to be tested is displayed in a mode of the plurality of the mold progress bars, so that a tester can quickly and accurately judge the electric quantity of the battery to be tested at a glance without excessively analyzing the test voltage of the battery to be tested.
Drawings
FIGS. 1 and 2 are schematic views of a prior art product;
FIG. 3 is a schematic block diagram of a first embodiment of the present invention;
FIG. 4 is a schematic circuit diagram of a first embodiment of the present invention;
fig. 5 is a discharge curve diagram of the discharge resistor 620 Ω of the 9V battery provided in the second embodiment;
fig. 6 is a discharge curve diagram of the discharge resistance 180 Ω of the 9V battery provided in the second embodiment;
FIG. 7 is a design logic diagram and display effect diagram of a multimeter display provided in accordance with a second embodiment.
The reference numbers in the figures denote:
1. an input terminal; 2. a gear selector switch; 3. a power supply circuit; 4. a dual impedance measurement circuit; 41. a high input impedance circuit; 42. a low input impedance circuit; 5. an ADC converter; 6. a DSP digital processor; 7. an LCD display screen; 8. a battery power monitoring circuit,
Detailed Description
The invention is described in detail below with reference to the figures and the specific embodiments.
Example one
Referring to fig. 3 and 4, the double-impedance input multimeter comprises an input terminal 1, a gear shift switch 2, a power supply circuit 3, a double-impedance measurement circuit 4, an ADC converter 5, a DSP digital processor 6 and an LCD display screen 7; the gear selector switch 2 is used for switching the measuring range of the multimeter; the power supply circuit 3 comprises a battery and provides working voltage for the multimeter; the double-impedance measuring circuit 4 comprises a high input impedance circuit 41 and a low input impedance circuit 42, an input end of the high input impedance circuit 41 is electrically connected with the input terminal 1, an output end of the high input impedance circuit is electrically connected with the ADC converter 5 through the shift switch 2, an input end of the low input impedance circuit 42 is electrically connected with the input terminal 1, an output end of the low input impedance circuit is electrically connected with the ADC converter 5 through the shift switch 2, and the double-impedance measuring circuit 4 transmits an electrical signal measured by the input terminal 1 to the ADC converter 5; the output end of the ADC converter 5 is electrically connected with the input end of the DSP digital processor 6, and the input electric signal is converted into a digital signal and is transmitted to the DSP digital processor 6; the output end of the DSP digital processor 6 is electrically connected with the LCD display screen 7, and the DSP digital processor 6 converts digital signals into driving signals of the LCD display screen 7 to drive the LCD display screen 7 to display corresponding data.
Further, the gear shift switch 2 includes a plurality of sets of golden finger contact pieces; referring specifically to fig. 4, S1, S2, S3, S4, S5, S6, S7, S8, S9, S10 and S11 in the drawing are each gold finger contact pieces; in this embodiment, the shift level of the shift level switch 2 includes an AC/DC/BAT (measurement of high impedance AC/DC voltage and no load of the battery) level, an L (BAT/AC/DC) (measurement of low power consumption battery and low input impedance voltage) level, an M (BAT) (medium power consumption battery) level, an H (BAT) (high power consumption battery) level, and an OHM (resistance measurement) level.
Further, the high input impedance circuit 41 includes a high resistance resistor (the high resistance resistor in this embodiment is R25 in fig. 4, and R25 is a precision resistor of 10M Ω), one end of the high resistance resistor is electrically connected to the input terminal 1, and the other end is electrically connected to the input terminal of the ADC converter 5; the low input impedance circuit 42 includes a plurality of low resistance resistors with different resistances, in this embodiment, the low resistance resistors include thermistors PTC1, PTC2, and PTC3, the resistance of the PTC1 is 1K Ω, the resistance of the PTC2 is 150 Ω, and the resistance of the PTC3 is 27 Ω; one end of the PTC1 is connected with an INPUT end of the INPUT terminal, the other end of the PTC1 is connected with the metal contact sheet S1, the metal contact sheets S1 and the metal contact sheets S3 form a group, and the other end of the metal contact sheet S3 is grounded; one end of the PTC3 is connected with an INPUT end of the INPUT terminal, the other end of the PTC3 is connected with a metal contact sheet S10, and the metal contact sheet S10 and the metal contact sheet S3 form a group; one end of the PTC2 is connected with a junction point of the PTC3 and the metal contact piece S10, the other end of the PTC2 is connected with the metal contact piece S2, and the metal contact piece S2 and the metal contact piece S3 form a group; when the metal contact sheet S1 is connected with the metal contact sheet S3, the equivalent circuit of the double-impedance measuring circuit 4 is that the PTC1 is connected with the resistor R25 in parallel; when the metal contact sheet S1 is connected with the metal contact sheet S10, the equivalent circuit of the double-impedance measuring circuit 4 is that the PTC3 is connected with the resistor R25 in parallel; when the metal contact sheet S1 and the metal contact sheet S2 are connected, the equivalent circuit of the double-impedance measuring circuit 4 is that the PTC2 and the PTC3 are connected in series and then connected in parallel with the resistor R25.
Further, the power supply circuit 3 includes a voltage-stabilizing power supply chip (U2 in fig. 4), an input end V + of the voltage-stabilizing power supply chip is connected with the metal contact piece S8, the metal contact piece S8 is connected with the metal contact piece S9 in a group, the metal contact piece S9 is connected with the positive electrode of the battery, a ground end V-of the voltage-stabilizing power supply chip is connected with the negative electrode of the battery, and an output end VDD of the voltage-stabilizing power supply chip provides working voltage for an electrical appliance in the multimeter.
The battery power monitoring circuit 8 comprises a voltage-dividing resistor R4 and a voltage-dividing resistor R20, wherein one end of the voltage-dividing resistor R4 is connected with the input end V + of the voltage-stabilizing power supply chip, the other end of the voltage-dividing resistor R4 is connected with one end of the voltage-dividing resistor R20, and the other end of the voltage-dividing resistor R20 is connected with the grounding end V-of the voltage-stabilizing power supply chip; the node of the voltage dividing resistor R4 connected with the voltage dividing resistor R20 is electrically connected with the input end of the ADC converter 5, and transmits a battery voltage signal to the ADC converter, and the voltage of the battery is obtained after voltage division by the resistor R4 and the resistor R20, and has the size: v + R20/(R4 + R20), the voltage is processed by the DSP 6, and drives the LCD 7 to display the battery power.
Further, the ADC converter 5 and the DSP digital processor 6 are integrated into a multimeter automatic range conversion chip IC1, and the multimeter automatic range conversion chip IC1 is a chip of SD7830 type.
In this embodiment, when the shift of the shift switch 2 is switched to AC/DC/BAT (measurement of high impedance AC/DC voltage and no load of the battery), the INPUT end of the INPUT terminal 1 is connected to one end of the resistor R25, the other end of the resistor R25 is connected to the multimeter automatic range conversion chip IC1, and the resistor R25 is used as the INPUT impedance, so the INPUT impedance of the high INPUT impedance circuit is 10 Μ Ω; when the gear of the gear change-over switch 2 is in the L (BAT/AC/DC) (low-power battery and low-INPUT impedance voltage measurement) gear, the metal contact sheet S1 and the metal contact sheet S3 are connected, the INPUT end of the INPUT terminal 1 is respectively connected with one end of a resistor R25 and one end of a resistor PTC1, the other end of the resistor R25 is connected to an automatic range conversion chip IC1 of the multimeter, the other end of the PTC1 is grounded, the INPUT impedance is equivalent to the parallel value of the resistor R25 and the PTC1, and the resistance value of the resistor R25 is far greater than that of the PTC1, so the INPUT impedance of the L (BAT/AC/DC) gear is 1K omega of the resistance value of the PTC 1; when the gear of the gear shift switch 2 is switched to the M (BAT) (medium power battery) gear, the metal contact sheet S2 and the metal contact sheet S3 are connected, the INPUT end is connected with one end of the resistor R25 and one end of the resistor PTC3 respectively, the other end of the resistor R25 is connected to the multimeter automatic range conversion chip IC1, the other end of the PTC3 is connected with one end of the PTC2, the other end of the PTC2 is grounded through the metal contact sheet S2 and the metal contact sheet S3, the INPUT impedance is equivalent to the parallel value of the resistor R and the resistor 25 after the PTC3 and the PTC2 are connected in series, because the resistance value of the resistor R25 is much greater than that of the PTC2 and the PTC3, the INPUT impedance of the M (BAT) gear is the series value of 150 Ω =177 Ω of the PTC2 and the PTC 3; when the gear of the gear change-over switch 2 is switched to the H (BAT) (high power consumption battery) gear, the metal contact sheet S10 and the metal contact sheet S3 are connected, the INPUT end of the INPUT terminal 1 is respectively connected with one end of the resistor R25 and one end of the resistor PTC3, the other end of the resistor R25 is connected to the automatic range conversion chip IC1 of the multimeter, the other end of the PTC3 is grounded through the metal contact sheet S10 and the metal contact sheet S3, the INPUT impedance is equivalent to the parallel value of the resistor R25 and the PTC3, and because the resistance value of the resistor R25 is far larger than that of the PTC3, the INPUT impedance of the H (BAT) gear is 27 ohms of the resistance value of the PTC 3; when the shift switch 2 is turned on in an OHM (resistance measurement) shift, the metal contact piece S4 is connected to the metal contact piece S5, and the metal contact piece S6 is connected to the metal contact piece S7; the INPUT end of the INPUT terminal 1 is respectively connected with one end of a PTC1 and one end of a resistor R59, the other end of the PTC1 is connected with one end of a resistor R30 and an emitting electrode of a triode Q4 through a metal contact sheet S1, a metal contact sheet S4 and a metal contact sheet S5, the other end of the resistor R30 is connected to an automatic range conversion chip IC1 of the multimeter, the other end of the resistor R59 is connected to the automatic range conversion chip IC1 of the multimeter through a metal contact sheet S6 and a metal contact sheet S7, a standard voltage is sent out by the automatic range conversion chip IC1 of the multimeter during measuring the resistor and is added to the two ends of the resistor to be measured through the PTC1 of the resistor R30, the voltage drop at the two ends of the resistor to be measured is added to the automatic range conversion chip IC1 of the multimeter through the resistor R59, and after data processing is carried out by the automatic range conversion chip IC1 of the multimeter, an LCD display screen 7 is driven to display a measuring result; PTC1 and Q4, Q5 are resistance shelves protection circuit, play the guard action to the circuit after the input end mistyped input a voltage signal.
Example two:
a method of displaying battery power on a multimeter comprising the steps of:
pre-writing the relation between the voltage value of each specification battery and the battery electric quantity in a processing chip of the universal meter;
selecting a measuring range on a universal meter according to the nominal voltage of the battery to be measured;
detecting the voltage value of the battery to be detected, and sending the voltage value to a processing chip of the universal meter;
the processing chip of the universal meter converts the voltage value of the battery to be tested into the battery capacity of the current battery to be tested according to the voltage value of the battery to be tested, and drives a display screen of the universal meter to display corresponding data;
the battery to be tested can be a battery detected on an input terminal of the universal meter or a power supply battery of the universal meter.
Further, the specific method for pre-writing the relationship between the voltage value of each specification battery and the battery capacity in the processing chip of the multimeter comprises the following steps:
acquiring a discharge curve of each specification battery according to the discharge resistance of each specification battery in the universal meter;
according to the corresponding battery discharge curve, the electric quantity of each specification battery is divided into a plurality of equal parts, and the maximum voltage value and the minimum voltage value of each equal division interval are obtained;
and according to the maximum voltage value and the minimum voltage value of each equal division interval, the battery electric quantity of the battery with the corresponding specification is graduated and written into a processing chip of the universal meter.
Further, the specific method for converting the processing chip of the multimeter into the battery capacity of the current battery to be tested according to the voltage value of the battery to be tested and driving the display screen of the multimeter to display the corresponding data is as follows:
comparing the voltage value of the battery to be measured with the scale of the battery with the corresponding specification, and dividing the voltage value into corresponding equal division intervals;
and a processing chip of the multimeter drives a display screen to display corresponding battery capacity data according to the battery capacity corresponding to the equal division interval into which the voltage value of the battery to be tested is divided.
Further, the battery electric quantity data is displayed in a progress bar mode; each equally-divided interval corresponds to different progresses of the progress bar, and the processing chip of the universal meter drives the progress bar on the display screen to display corresponding progresses according to the corresponding equally-divided interval; referring to FIG. 7, the progress bar form in this embodiment includes a full grid symbolThree-grid symbolTwo-lattice symbolOne grid symbolAnd space symbol
The implementation process of the embodiment is described below by taking the multimeter in the first embodiment as an example:
displaying the electric quantity of the power supply battery: the relation between the voltage value of the power supply battery and the battery capacity is written in a processing chip IC1 of the multimeter in advance, for example, a common 9V laminated battery (6F 22 acid zinc-manganese dry battery) of the digital multimeter, because a main power consumption device IC1 is a micro-power consumption device, the discharge resistance of about 1.5mA of the battery working current can be equivalent to the resistance of 620 omega, and the discharge resistance of the battery is obtainedReferring to the electrical curve (see fig. 5), for a dry cell, when the normal voltage drops to 75% of the nominal voltage value, i.e. 9 × 0.75=6.75v, it can be considered that the battery needs to be replaced when the battery is exhausted, referring to the battery discharge curve of fig. 5, the battery power is divided into 5 equal parts when the battery voltage is greater than 6.75V, and the corresponding voltages are: 7.95V,7.73V,7.54V,7.20V and 6.75V, namely the current battery power is divided into 7.95-9V, 7.73-7.95V, 7.54-7.73V, 7.20-7.54V and 6.75-7.20V; when the electric quantity of the power supply battery is selected to be measured on a multimeter, the voltage of the power supply battery is detected, and when the battery voltage belongs to an equal division interval of 7.95V-9V or 7.73V-7.95V, the available electric quantity of the battery is larger than 60 percent, and the good battery state is represented by a Manger symbolThe indication is that when the battery voltage is 7.54V-7.73V, a three-grid symbol is usedIt is indicated that the battery voltage is 7.20V-7.54V and the two-grid symbol is usedThe indication is that a grid symbol is used when the battery voltage is between 6.75V and 7.20VIndicating that the battery voltage is lower than 6.75V by using a space markThe prompt indicates that the battery must be replaced when the battery is exhausted.
Displaying the battery process detected on the input terminal of the multimeter: writing the relation between the voltage value and the battery capacity of each specification battery in a processing chip IC1 of a multimeter in advance, taking a 9V laminated battery (6F 22 acid zinc manganese dry battery) as an example, when the 9V battery is detected in the first embodiment, selecting a gear as an M (BAT) gear for measurement, wherein the input impedance, namely the discharge resistance value of the M (BAT) gear is about 180 omega, and obtaining the discharge of the 9V laminated battery when the discharge resistance is 180 omegaCurves (see fig. 6); referring to the battery discharge curve of fig. 6, the battery voltage greater than 6.75V is divided into 5 equal parts, and the corresponding voltages are: 7.74V,7.3V,7.07V,6.92V and 6.75V, namely the current battery power is divided into 7.74V-9V, 7.3V-7.74V, 7.07V-7.3V, 6.92V-7.07V and 6.75V-6.92V; when the electric quantity of the power supply battery is selected to be measured on a multimeter, the voltage of the power supply battery is detected, and when the battery voltage belongs to a 7.74-9V or 7.3-7.74V equal division interval, the available electric quantity of the battery is larger than 60 percent, and the good battery state is represented by a Manger symbolIt is indicated that a three-grid symbol is used when the battery voltage is 7.07V to 7.3VIt is indicated that a two-grid symbol is used when the battery voltage is 6.92V-7.07VThe indication is that a grid symbol is formed when the battery voltage is between 6.75V and 6.92VIndicating that the battery voltage is lower than 6.75V by using a space markThe prompt indicates that the battery must be replaced when the battery is exhausted.
Taking a 3.7V lithium ion rechargeable battery as an example, the actual voltage value after full charge is normally 4.2V, the optimal charging time is 50-60% of electric quantity consumption, and if the electric quantity consumption exceeds 60% for recharging, the service life of the battery is influenced; the battery voltage and the battery capacity of the 3.7V lithium ion rechargeable battery in no-load state have the following relationship: 4.20V/100%;4.06V/90%;3.98V/80%;3.92V/70%;3.87V/60%;3.82V/50%;3.79V/40%;3.74V/30%;3.68V/10%, and writing the relation between the battery voltage and the battery capacity into a processing chip IC1 of the multimeter; when the available electric quantity of the battery is more than 80 percentManger symbol for indicating battery state is goodIt is suggested that when the battery voltage is lower than 3.98V, the available battery power is lower than 80%, and the three-grid symbol is usedAnd prompting that a two-grid symbol is used for indicating that the available electric quantity of the battery is lower than 70% when the voltage of the battery is lower than 3.92VIt is indicated that a cell symbol is used to indicate that the available battery capacity is less than 60% when the battery voltage is less than 3.87VIndicating that a space symbol is used when the battery voltage is lower than 3.82The indication shows that the available electric quantity of the battery is less than 50%, and the battery needs to be charged in time, and the space symbol is marked when the voltage of the battery is less than 3.79VThe tester will continuously flash to remind the tester that the available battery capacity is lower than 40%, and the service life of the battery is affected if the battery is not charged in time.
Although the discharge curves of the batteries with the same voltage specification cannot be completely consistent due to different material processes of the batteries, a prompt is given to the electric quantity of the batteries (the batteries with a certain specification can only be selected for calibration regardless of the load, the batteries with other models and specifications can only be used as a reference, but the voltage value of the battery with any specification can be measured for the voltage measurement value), and the prompt has stronger reference significance for engineering technicians.
The above description is only an embodiment of the present invention, and is not intended to limit the scope of the present invention, and all equivalent structures or equivalent processes performed by the present invention or directly or indirectly applied to other related technical fields are included in the scope of the present invention.
Claims (10)
1. A dual impedance input multimeter comprising: the device comprises an input terminal (1), a gear selector switch (2), a power supply circuit (3), a double-impedance measurement circuit (4), an ADC (analog to digital converter) converter (5), a DSP (digital signal processor) (6) and an LCD (liquid crystal display) screen (7); the gear selector switch (2) is used for switching the measuring range of the multimeter; the power supply circuit (3) comprises a battery and provides working voltage for the universal meter; the double-impedance measuring circuit (4) comprises a high input impedance circuit (41) and a low input impedance circuit (42), wherein the input end of the high input impedance circuit (41) is electrically connected with the input terminal (1), the output end of the high input impedance circuit is electrically connected with the ADC (5) through a gear selector switch (2), the input end of the low input impedance circuit (42) is electrically connected with the input terminal (1), the output end of the low input impedance circuit is electrically connected with the ADC (5) through the gear selector switch (2), and the double-impedance measuring circuit (4) transmits an electric signal measured by the input terminal (1) to the ADC (5); the output end of the ADC converter (5) is electrically connected with the input end of the DSP digital processor (6), and the input electric signal is converted into a digital signal and is transmitted to the DSP digital processor (6); the output end of the DSP digital processor (6) is electrically connected with the LCD display screen (7), and the DSP digital processor (6) converts digital signals into driving signals of the LCD display screen (7) and drives the LCD display screen (7) to display corresponding data.
2. A dual impedance input multimeter as recited in claim 1, wherein: the gear shift switch (2) comprises a plurality of groups of golden finger contact pieces.
3. A dual impedance input multimeter as recited in claim 2, wherein: the high-input impedance circuit (41) comprises a high-resistance resistor, one end of the high-resistance resistor is electrically connected with the input terminal (1), and the other end of the high-resistance resistor is electrically connected with the input end of the ADC (5); the low input impedance circuit (42) comprises a plurality of low-resistance resistors with different resistances, one end of each low-resistance resistor is electrically connected with the input terminal (1), the other end of each low-resistance resistor is electrically connected with each group of golden finger contact pieces on the gear switching switch (2), and after one group of golden finger contact pieces are connected, the corresponding low-resistance resistors are connected with the high-resistance resistors in parallel.
4. A dual impedance input multimeter as recited in claim 2, wherein: the power supply circuit (3) comprises a voltage-stabilizing power supply chip, the input end of the voltage-stabilizing power supply chip is connected with the positive electrode of the battery through a group of golden finger contact pieces, the grounding end of the voltage-stabilizing power supply chip is connected with the negative electrode of the battery, and the output end of the voltage-stabilizing power supply chip provides working voltage for electric appliances in the multimeter.
5. A dual impedance input multimeter as recited in claim 4, wherein: the battery power monitoring circuit (8) comprises a divider resistor R4 and a divider resistor R20, one end of the divider resistor R4 is connected with the input end of the voltage-stabilizing power supply chip, the other end of the divider resistor R20 is connected with one end of the divider resistor R20, and the other end of the divider resistor R20 is connected with the grounding end of the voltage-stabilizing power supply chip; the junction point that divider resistance R4 and divider resistance R20 are connected with the input electricity of ADC converter (5) is connected, transmits battery voltage signal to it, ADC converter (5) carry behind the battery voltage signal conversion digital signal to DSP digital processor (6), DSP digital processor (6) drive LCD display screen (7) show the battery power.
6. A dual impedance input multimeter as recited in claim 5, wherein: the ADC converter (5) and the DSP digital processor (6) are integrated in a universal meter automatic range conversion chip IC 1.
7. A method of displaying battery charge on a multimeter comprising the steps of:
pre-writing the relation between the voltage value of each specification battery and the battery electric quantity in a processing chip of the universal meter;
selecting a measuring range on a universal meter according to the nominal voltage of the battery to be measured;
detecting the voltage value of the battery to be detected, and sending the voltage value to a processing chip of the universal meter;
the processing chip of the universal meter converts the voltage value of the battery to be tested into the battery capacity of the current battery to be tested according to the voltage value of the battery to be tested, and drives a display screen of the universal meter to display corresponding data;
the battery to be tested can be a tested battery detected on an input terminal of the universal meter or a power supply battery of the universal meter.
8. The method for displaying the battery power on the multimeter according to claim 7, wherein the specific method for pre-writing the relationship between the voltage value of each specification battery and the battery power in a processing chip of the multimeter is as follows:
acquiring a discharge curve of each specification battery according to the discharge resistance of each specification battery in the universal meter;
according to a corresponding battery discharge curve, the electric quantity of each specification battery is divided into a plurality of equal parts, and the maximum voltage value and the minimum voltage value of each equal division interval are obtained;
and according to the maximum voltage value and the minimum voltage value of each equal division interval, the battery electric quantity of the battery with the corresponding specification is graduated and written into a processing chip of the universal meter.
9. The method for displaying the battery power on the multimeter according to claim 8, wherein the specific method that a processing chip of the multimeter converts the voltage value of the battery to be tested into the battery power of the current battery to be tested and drives a display screen of the multimeter to display the corresponding data is as follows:
comparing the voltage value of the battery to be tested with the scales of the battery with the corresponding specification, and dividing the voltage value into corresponding equal intervals;
and a processing chip of the multimeter drives a display screen to display corresponding battery electric quantity data according to the battery electric quantity corresponding to the equal division interval into which the voltage value of the battery to be tested is divided.
10. The method of claim 9, wherein the method further comprises the step of: displaying the battery electric quantity data in a progress bar mode; each equal interval corresponds to different progresses of the progress bar, and the processing chip of the universal meter drives the progress bar on the display screen to display the corresponding progress according to the corresponding equal interval.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN113281549A (en) * | 2021-05-28 | 2021-08-20 | 上海应用技术大学 | Modified digital multimeter and method for measuring pH and ion concentration of solution |
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