CN114545055A - Circuit for adding milliohm measurement to ordinary multimeter and using method - Google Patents
Circuit for adding milliohm measurement to ordinary multimeter and using method Download PDFInfo
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- CN114545055A CN114545055A CN202210447633.1A CN202210447633A CN114545055A CN 114545055 A CN114545055 A CN 114545055A CN 202210447633 A CN202210447633 A CN 202210447633A CN 114545055 A CN114545055 A CN 114545055A
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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
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R1/00—Details of instruments or arrangements of the types included in groups G01R5/00 - G01R13/00 and G01R31/00
- G01R1/30—Structural combination of electric measuring instruments with basic electronic circuits, e.g. with amplifier
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J7/0047—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with monitoring or indicating devices or circuits
- H02J7/0048—Detection of remaining charge capacity or state of charge [SOC]
- H02J7/0049—Detection of fully charged condition
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J7/007—Regulation of charging or discharging current or voltage
- H02J7/00712—Regulation of charging or discharging current or voltage the cycle being controlled or terminated in response to electric parameters
- H02J7/00714—Regulation of charging or discharging current or voltage the cycle being controlled or terminated in response to electric parameters in response to battery charging or discharging current
- H02J7/00716—Regulation of charging or discharging current or voltage the cycle being controlled or terminated in response to electric parameters in response to battery charging or discharging current in response to integrated charge or discharge current
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J7/007—Regulation of charging or discharging current or voltage
- H02J7/007188—Regulation of charging or discharging current or voltage the charge cycle being controlled or terminated in response to non-electric parameters
- H02J7/007192—Regulation of charging or discharging current or voltage the charge cycle being controlled or terminated in response to non-electric parameters in response to temperature
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J7/007—Regulation of charging or discharging current or voltage
- H02J7/007188—Regulation of charging or discharging current or voltage the charge cycle being controlled or terminated in response to non-electric parameters
- H02J7/007192—Regulation of charging or discharging current or voltage the charge cycle being controlled or terminated in response to non-electric parameters in response to temperature
- H02J7/007194—Regulation of charging or discharging current or voltage the charge cycle being controlled or terminated in response to non-electric parameters in response to temperature of the battery
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J2207/00—Indexing scheme relating to details of circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J2207/30—Charge provided using DC bus or data bus of a computer
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Abstract
The invention relates to a circuit for increasing milliohm measurement for a common multimeter and a using method thereof, wherein 2 leads are led out from an output socket XS2 of the circuit and connected to 2 pins of a device to be measured, a pair of meter pens of the multimeter are also connected to the 2 pins of the device to be measured, the multimeter is switched to the lowest level of direct current voltage, a switch S1 of the circuit is closed, the output voltage of a constant voltage source circuit generates 1A current on the device to be measured due to the constant current function of a constant current source circuit, the universal meter pens are connected in parallel at two ends of the device to be measured, the voltage drop of the device to be measured is measured according to the ohm law: r = U/I, and the resistance value of the device to be tested = xx millivolts/1 ampere = xx milliohms of the reading of the multimeter. The ordinary multimeter is added with only one milliohm resistance measuring circuit of the invention, and the measuring function of the resistance with the small resistance value of 0.001 omega-1 omega can be completed.
Description
Technical Field
The invention relates to the field of electronic measuring instruments, in particular to a circuit for adding milliohm measurement to a common multimeter and a using method thereof.
Background
The universal meter is widely used due to convenient carrying, low price and rich functions in the actual circuit measurement process, and can meet the general requirements on the measurement precision of voltage, current and most resistance values.
The DC voltage range of the ordinary multimeter is generally 200mV at least, the resistance range is 1 omega at least, however, due to the contact resistance of the internal function switch and the limitation of the output current of the dry battery, the measurement of the resistance value (m omega level) of the resistor below 1 omega is extremely inaccurate, in the practical use process, the m Ω -level resistance measurement is still more, for example, the contact resistance measurement of a switch, the resistance measurement of a lead, the resistance measurement of a printed wire on a circuit board, the search of a short circuit point on the circuit board and the like, the resistance value to be measured is smaller, usually between several milliohms and several hundred milliohms, for these small resistance measurements, existing multimeters do not measure, or the measurement error is large, at this time, a milliohmmeter or a bridge is generally needed for measurement, but the milliohmmeter and the bridge are heavy, and some milliohmmeter and the bridge need an alternating current power supply to supply power, so that the use is inconvenient.
Disclosure of Invention
In view of the defects of the existing ordinary multimeter in the aspect of measuring small-resistance resistors, the invention provides a circuit for increasing the measurement of milliohm resistors for the ordinary multimeter and a using method thereof.
In order to achieve the purpose, the invention adopts the technical scheme that: a circuit for increasing milliohm measurement for a common multimeter comprises a lithium battery, a charging circuit, a 1.25V constant voltage circuit and a 1A constant current source circuit;
the lithium battery is respectively connected with the charging circuit, the 1.25V constant voltage circuit and the 1A constant current source circuit;
the charging circuit is used for charging the lithium battery;
the lithium battery is used for supplying power to the 1.25V constant voltage circuit and the 1A constant current source circuit;
the 1.25V constant voltage circuit is used for generating 1.25V constant voltage by a power supply provided by the lithium battery;
the 1A constant current source circuit is used for enabling a power supply provided by the lithium battery to generate constant 1A current on a load.
The charging circuit comprises a socket XS1, an integrated circuit N3, a resistor R9, a resistor R10, a resistor R11, a capacitor C10, a capacitor C11, a capacitor C12, a capacitor C13, an indicator lamp VD3 and an indicator lamp VD 4;
the power supply comprises a socket XS1, a pin 1, a pin 4 and a pin 8 of an integrated circuit N3, a positive electrode of a capacitor C10, one end of a capacitor C11, one ends of a resistor R10 and a resistor R11 are connected to a node +5V _ in, a pin 1 and a pin 3 of the integrated circuit N3 and a pin 5 of the socket XS1 are grounded, a pin 2 of the integrated circuit N3 is grounded through a resistor R9, a negative electrode of the capacitor C10 and the other end of the capacitor C11 are grounded, the other end of the resistor R10 is connected to a positive electrode of a diode VD3, a negative electrode of the diode VD3 is connected to a pin 6 of the integrated circuit N3, the other end of the resistor R3 is connected to a positive electrode of the diode VD3, a negative electrode of the diode VD3 is connected to a pin 7 of the integrated circuit N3, the pin 5 of the integrated circuit N3 is connected to a positive electrode of a lithium battery, a positive electrode of the capacitor C3, one end of the capacitor C3 and one end of the switch S3, and a negative electrode of the capacitor GB 3 of the lithium battery C3 and a negative electrode of the capacitor C3 of the lithium battery 3 and a ground;
integrated circuit N3 is model TP 4056.
The 1.25V constant-voltage circuit comprises an integrated circuit N1, a resistor R1, a resistor R2, a capacitor C1, a capacitor C2, a capacitor C3, a capacitor C4, a capacitor C5, an inductor L1 and a diode VD 1;
one end of a pin 1 of the integrated circuit N1, the anode of the capacitor C1 and one end of the capacitor C2 are connected to the node + BAT and the other end of the switch S1, a pin 3 and a pin 5 of the integrated circuit N1, the cathode of the capacitor C1 and the other end of the capacitor C2 are grounded, a pin 2 of the integrated circuit N1 is connected to the cathode of the diode VD1 and one end of the inductor L1, the other end of the inductor L1, the anode of the capacitor C4, the capacitor C3, the capacitor C5 and one end of the resistor R2 are connected to a pin 2 of the output socket XS2, the other end of the capacitor C3 and the cathode of the capacitor C4 are grounded, the other ends of the resistor R2 and the capacitor C5 are connected to a pin 4 of the integrated circuit N1 and one end of the resistor R1, and the other end of the resistor R1 is grounded;
the integrated circuit N1 is model LM 2596S-ADJ.
The 1A constant current source circuit comprises an operational amplifier N2, a field effect transistor VT1, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R7, a resistor R8, a capacitor C6, a capacitor C7, a capacitor C8 and a capacitor C9;
the pin 7 of the operational amplifier N2, the anode of the capacitor C7, one end of the capacitor C6 and one end of the resistor R3 are connected to the node + BAT and the other end of the switch S1, the other end of the capacitor C6 and the cathode of the capacitor C7 are grounded, the other end of the resistor R3 is connected with one end of a resistor R4 and the anode of the diode VD2, the cathode of the diode VD2 is grounded, the other end of the resistor R4 is grounded through a resistor R5, the connecting point of the resistor R4 and the resistor R5 is connected with a pin 3 of an operational amplifier N2, the 2-pin of the operational amplifier N2 is connected with the source of the field effect transistor VT1, one end of the capacitor C9 and one end of the resistor R8, the other ends of the capacitor C9 and the resistor R8 are grounded, a pin 6 of the operational amplifier N2 is connected to the grid of the field effect transistor VT1, the anode of the capacitor C8 and one end of the resistor R7 through the resistor R6, the negative electrode of the capacitor C8, the other end of the resistor R7 and the 4 pin of the operational amplifier N2 are grounded, and the drain electrode of the field effect transistor VT1 is connected to the 1 pin of the output socket XS 2;
operational amplifier N2 was model AD 8638.
A circuit using method for increasing milliohm measurement for a common multimeter is characterized in that 2 leads are led out from an output socket XS2 of the circuit and connected to 2 pins of a device to be measured, a pair of meter pens of the multimeter is also connected to the 2 pins of the device to be measured, the multimeter is dialed to the lowest level of direct-current voltage, a switch S1 of the circuit is closed, due to the constant-current effect of a constant-current source circuit, the output voltage of the constant-voltage source circuit generates 1A current on the device to be measured, the universal meter pens are connected to two ends of the device to be measured in parallel, the voltage drop of the device to be measured is measured, and according to the ohm law:
R=U/I，
the device under test resistance = multimeter reading xx millivolts/1 ampere = xx milliohms,
if the voltage measured by the multimeter exceeds the measuring range, the multimeter is dialed to the previous gear of the lowest direct-current voltage gear, and at the moment, the multimeter is used for shifting to the previous gear of the lowest direct-current voltage gear
The resistance value of the device to be tested = xx volts/1 ampere = xx ohm.
The invention has the beneficial effects that:
the common multimeter is added with only one milliohm resistance measuring circuit of the invention, the measuring function of the resistance with small resistance value of 0.001 omega-1 omega can be completed, the cost of the added circuit is about 20 yuan, but the measuring function of the resistance with several hundred to thousands yuan can be completed, the volume is small and exquisite, is not more than 70 multiplied by 50 multiplied by 22mm, the weight is less than 50 grams, the carrying is convenient, the precision of the measured small resistance value is less than 2.5 percent, and the measuring circuit is equivalent to the milliohm meter of a precision instrument grade, and completely meets the general measuring requirement.
Drawings
FIG. 1 is a block diagram of the circuit connections of the present invention;
FIG. 2 is a schematic diagram of the circuit of the present invention;
FIG. 3 is a circuit connection block diagram according to an embodiment of the invention.
Detailed Description
As shown in FIG. 1, a circuit for increasing milliohm measurement of a common multimeter comprises a lithium battery, a charging circuit, a 1.25V constant voltage circuit and a 1A constant current source circuit;
the lithium battery is used for supplying power to the 1.25V constant voltage circuit and the 1A constant current source circuit;
the 1.25V constant voltage circuit uses power supplied by a lithium battery to generate 1.25V constant voltage;
the 1A constant current source circuit uses power supplied by a lithium battery to generate constant 1A current.
This circuit can be equipped with 5V power adapter, and 5V power adapter is used for charging for the lithium cell of circuit, need not connect power adapter during normal use, only just connects power adapter to charge under the not enough condition of lithium cell electric quantity.
The charging circuit has the functions of constant voltage and current-limiting charging, converts a 5V power supply provided by the power adapter into 4.2V power supply, charges an internal lithium battery, detects charging current in the charging process, judges that the charging current is full to a certain degree and ends the charging process.
The 1.25V constant voltage circuit generates 1.25V constant voltage, so that the voltage is used, on one hand, the low voltage is used as much as possible when the circuit is tested so as to avoid damage to the tested circuit, and the 1.25V is the minimum stabilized voltage output value of the stabilized voltage device.
The socket XS1 is of a Micro USB type, can be connected with a mobile phone charging wire of a widely used Micro USB head, and charges a unit circuit;
the integrated circuit N3 is TP4056, and is a special lithium battery charging management chip.
The integrated circuit N1 is LM2596S-ADJ, which is an output adjustable DC/DC chip.
The operational amplifier N2 is AD8638, which is used for accurately controlling the output current to be constant.
As shown in FIG. 2, the nominal voltage of the lithium battery GB1 is 3.7V, the lithium battery is supplied with power for a 1.25V constant voltage circuit and a 1A constant current source circuit, an integrated circuit N1 in the 1.25V constant voltage circuit is a DC/DC chip, the output voltage amplitude of the integrated circuit is determined by the proportion of a sampling resistor R1 and a resistor R2, and V is determined by the proportion of a sampling resistor R1 to a resistor R2OUT=1.23 (R1+ R2)/R1=1.23 (120+2)/120=1.25V, inductor L1 is an energy storage inductor, VD1 is a freewheeling diode, the continuity of current in inductor L1 is maintained, and capacitor C3 and capacitor C4 are filter capacitors, and ripples on the output are filtered;
the 1A constant current source circuit is composed of devices such as an operational amplifier N2, a field effect tube VT1, a resistor R8 and the like, a load current is sampled by a resistor R8, a sampling voltage is obtained by multiplying the current by a sampling resistance value, the sampling voltage is added to the inverting terminal of the operational amplifier N2, a resistor R3 is connected in series with a diode VD2, a stable voltage is obtained by using the tube voltage drop of the diode, the voltage is divided by a resistor R3 and a resistor R4 and is added to the inverting terminal of the operational amplifier N2 as a reference voltage for setting an output current, the sampling voltage is compared with the reference voltage to determine the high and low of the output voltage, the output of the operational amplifier N2 passes through a filter of a resistor R6 and a capacitor C8 to drive the field effect tube VT1, when the current flowing in the sampling resistor becomes large, the sampling voltage rises, the output of the operational amplifier N2 becomes low, the field effect tube VT1 becomes low due to the grid source voltage and the on resistance increases, thereby reducing the current flowing through the capacitor and achieving the purpose of keeping the output current stable.
The working principle of the charging circuit;
the TP4056 integrated circuit N3 is a complete single-section lithium ion battery constant current/constant voltage charger, adopts an internal PMOSFET architecture, has an anti-reverse charging circuit, and can automatically adjust the charging current through internal thermal feedback so as to limit the temperature of a chip under high-power operation or high-temperature environment; the charging voltage is fixed at 4.2V, the precision is 1%, the accurate charging voltage plays a role in protecting the lithium battery, and the charging current can be set through an external resistor R9; when the charging current drops to 1/10 of the set value after reaching the final floating charge voltage, TP4056 will automatically terminate charging, avoiding the damage of continuous low current floating charge to the lithium battery after full charge.
When the input voltage (an alternating current adapter or a USB power supply connected with the XS 1) is removed, the TP4056 automatically enters a low current state, and the leakage current of the lithium battery is reduced to be below 2 uA;
the TP4056 also comprises the functions of lithium battery temperature detection, under-voltage locking and automatic recharging, and is provided with two pins for indicating the charging state; after the charging is finished, the 6 th pin of the integrated circuit N3 becomes low level, the 5 th pin becomes high level, the corresponding charging end indicator lamp diode VD3 is turned on, the charging indicator lamp diode VD4 is turned off, and the states of the 5 th pin and the 6 th pin, the diode VD3 and the diode VD4 are opposite to the charging end state in the charging process.
The working principle of the 1.25V constant-voltage circuit;
n1 in the 1.25V constant voltage circuit is an output adjustable DC/DC chip, and the output voltage amplitude is determined by the proportion of a sampling resistor R1 and a resistor R2:
VOUT=1.23*(R1+R2)/R1=1.23*(120+2)/120=1.25V
l1 is energy storage inductance, VD1 is a freewheeling diode, keeps the continuity of current in inductance L1, and electric capacity C3, electric capacity C4 are filter capacitance, filters the ripple on the output.
1A constant current source circuit working principle.
The 1A constant current source circuit comprises an operational amplifier N2, a field effect transistor VT1, a resistor R8 and other devices, a line current is sampled by a resistor R8, a sampling voltage is obtained by multiplying the current by a sampling resistance value, the sampling voltage is added to the inverting terminal of the operational amplifier N2, a resistor R3 is connected with a diode VD2 in series, a stable voltage is obtained by using the tube voltage drop of the diode, the voltage is divided by a resistor R3 and a resistor R4 and is added to the inverting terminal of the operational amplifier N2 as a reference voltage for setting an output current, the sampling voltage is compared with the reference voltage to determine the height of the output voltage, the output of the operational amplifier N2 passes through a resistor R6 and a filter driving field effect transistor VT1 of a capacitor C8, when the current flowing in the sampling resistor becomes large, the sampling voltage rises, the output of the operational amplifier N2 becomes low, the field effect transistor VT1 becomes low due to the gate source voltage, the on-resistance increases, thereby reducing the current flowing through the capacitor and achieving the purpose of keeping the output current stable.
As shown in fig. 3, the contact resistance of the fixed contact and the movable contact of the relay in example 1 is measured;
taking 1 JDX18 relays, connecting 2 wires led out from an output socket XS2 of the circuit to 2 pins of a static contact of a JDX18 relay to be tested, dialing to a 200mV direct current gear by using a universal meter, connecting 2 meter pens to 2 pins of the group of static contacts, reading 7mV of the universal meter at the moment, and calculating to obtain a static contact resistance of 7m omega;
the relay coil is powered on to attract the relay, 2 wires led out from an output socket XS2 of the circuit are connected to 2 pins of a JDX18 relay moving contact to be measured, 2 meter pens of a multimeter are also connected to the 2 pins of the group of moving contacts, and then the contact resistance of the moving contacts can be measured.
Example 2 search for short circuit points on a circuit board;
the most short-circuit faults on a new assembled circuit board are short circuits between a power supply and the ground, and when the problems occur, a common method is often difficult to find short-circuit points, because the number of components connected between the power supply and the ground is very large, which component is short-circuited is not well determined; by utilizing the circuit of the invention, 2 lines led out from an output socket XS2 of the circuit are connected to 2 test pens of the multimeter, the multimeter is switched to a 200mV DC gear, 1 test pen is connected with the ground of a circuit board to be checked, the other test pen is used for measuring the resistance value of each power supply point to the ground in a sectional manner, the point with the minimum resistance value is found out to be the short-circuit point, if the circuit of the invention is not connected, the measurement is carried out only by using the X1 omega gear of the multimeter, the reading of the multimeter has no change, and the short-circuit point can not be found out.
Example 3 wire gauge validation;
a 3 m copper wire, the specification of which needs to be confirmed, is used for measuring the resistance of the wire by using the circuit of the invention;
2 wires led out from an output socket XS2 of the circuit are connected to two ends of a lead, a circuit switch S1 is turned on, a universal meter is dialed to a DC200mV grade, two meter pens are connected to two ends of the lead to be measured, voltage drop on the lead is measured, the universal meter displays an out-of-range state, the universal meter is dialed to a DC2V grade, the reading is 0.245V, and the resistivity of a copper material at normal temperature is 1.678 multiplied by 10-8Ω m, the wire cross-sectional area is calculated as follows:
S=1.678×10-8×3/0.245=0.2055×10-6m2=0.2055mm2
looking up the AWG wire specification table, the above calculated value and the cross-sectional area of the 24# wire of 0.2047 mm2The nearest, so judge the wire specification to be measured is AWG24, it is identical with the specification that the wire supplier gives;
directly measuring the resistance of the lead by using a universal meter R multiplied by 1 omega, reading the resistance of the lead to be measured, changing the reading between 0.7 omega and 1.1 omega, taking the intermediate value of 0.9 omega, and calculating the sectional area of the lead to be measured to be 0.056 mm according to the value2The deviation is extremely large and unusable.
Claims (5)
1. A circuit for adding milliohm measurement to a common multimeter is characterized in that: the lithium battery charging circuit comprises a lithium battery, a charging circuit, a 1.25V constant voltage circuit and a 1A constant current source circuit;
the lithium battery is respectively connected with the charging circuit, the 1.25V constant voltage circuit and the 1A constant current source circuit;
the charging circuit is used for charging the lithium battery;
the lithium battery is used for supplying power to the 1.25V constant voltage circuit and the 1A constant current source circuit;
the 1.25V constant voltage circuit is used for generating 1.25V constant voltage by a power supply provided by the lithium battery;
the 1A constant current source circuit is used for enabling a power supply provided by the lithium battery to generate constant 1A current on a load.
2. A circuit for adding milliohm measurements to a common multimeter as recited in claim 1, wherein: the charging circuit comprises a socket XS1, an integrated circuit N3, a resistor R9, a resistor R10, a resistor R11, a capacitor C10, a capacitor C11, a capacitor C12, a capacitor C13, an indicator lamp VD3 and an indicator lamp VD 4;
the power supply comprises a socket XS1, a pin 1, a pin 4 and a pin 8 of an integrated circuit N3, a positive electrode of a capacitor C10, one end of a capacitor C11, one ends of a resistor R10 and a resistor R11 are connected to a node +5V _ in, a pin 1 and a pin 3 of the integrated circuit N3 and a pin 5 of the socket XS1 are grounded, a pin 2 of the integrated circuit N3 is grounded through a resistor R9, a negative electrode of the capacitor C10 and the other end of the capacitor C11 are grounded, the other end of the resistor R10 is connected to a positive electrode of a diode VD3, a negative electrode of the diode VD3 is connected to a pin 6 of the integrated circuit N3, the other end of the resistor R3 is connected to a positive electrode of the diode VD3, a negative electrode of the diode VD3 is connected to a pin 7 of the integrated circuit N3, the pin 5 of the integrated circuit N3 is connected to a positive electrode of a lithium battery, a positive electrode of the capacitor C3, one end of the capacitor C3 and one end of the switch S3, and a negative electrode of the capacitor GB 3 of the lithium battery C3 and a negative electrode of the capacitor C3 of the lithium battery 3 and a ground;
integrated circuit N3 is model TP 4056.
3. A circuit for adding milliohm measurements to a common multimeter as recited in claim 1, wherein: the 1.25V constant-voltage circuit comprises an integrated circuit N1, a resistor R1, a resistor R2, a capacitor C1, a capacitor C2, a capacitor C3, a capacitor C4, a capacitor C5, an inductor L1 and a diode VD 1;
one end of a pin 1 of the integrated circuit N1, the anode of the capacitor C1 and one end of the capacitor C2 are connected to the node + BAT and the other end of the switch S1, a pin 3 and a pin 5 of the integrated circuit N1, the cathode of the capacitor C1 and the other end of the capacitor C2 are grounded, a pin 2 of the integrated circuit N1 is connected to the cathode of the diode VD1 and one end of the inductor L1, the other end of the inductor L1, the anode of the capacitor C4, the capacitor C3, the capacitor C5 and one end of the resistor R2 are connected to a pin 2 of the output socket XS2, the other end of the capacitor C3 and the cathode of the capacitor C4 are grounded, the other ends of the resistor R2 and the capacitor C5 are connected to a pin 4 of the integrated circuit N1 and one end of the resistor R1, and the other end of the resistor R1 is grounded;
the integrated circuit N1 is model LM 2596S-ADJ.
4. A circuit according to claim 1 for adding milliohm measurements to a common multimeter, wherein: the 1A constant current source circuit comprises an operational amplifier N2, a field effect transistor VT1, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R7, a resistor R8, a capacitor C6, a capacitor C7, a capacitor C8 and a capacitor C9;
the pin 7 of the operational amplifier N2, the anode of the capacitor C7, one end of the capacitor C6 and one end of the resistor R3 are connected to the node + BAT and the other end of the switch S1, the other end of the capacitor C6 and the cathode of the capacitor C7 are grounded, the other end of the resistor R3 is connected with one end of a resistor R4 and the anode of the diode VD2, the cathode of the diode VD2 is grounded, the other end of the resistor R4 is grounded through a resistor R5, the connecting point of the resistor R4 and the resistor R5 is connected with a pin 3 of an operational amplifier N2, the 2-pin of the operational amplifier N2 is connected with the source of the field effect transistor VT1, one end of the capacitor C9 and one end of the resistor R8, the other ends of the capacitor C9 and the resistor R8 are grounded, a pin 6 of the operational amplifier N2 is connected to the grid of the field effect transistor VT1, the anode of the capacitor C8 and one end of the resistor R7 through the resistor R6, the negative electrode of the capacitor C8, the other end of the resistor R7 and the 4 pin of the operational amplifier N2 are grounded, and the drain electrode of the field effect transistor VT1 is connected to the 1 pin of the output socket XS 2;
operational amplifier N2 was model AD 8638.
5. A method of using the circuit of claim 1 to add milliohm measurements to a common multimeter, comprising: lead out 2 wires with this circuit output socket XS2 and connect 2 pins of awaiting measuring the device on, a pair of pen-shape metre of universal meter also receives 2 pins of awaiting measuring the device on, dial the universal meter to the lowest grade of direct current voltage, closed circuit ' S switch S1, because constant current source circuit ' S constant current effect, make constant voltage source circuit ' S output voltage produce 1A ' S electric current on the device that awaits measuring, the general purpose pen-shape metre connects in parallel at the device both ends that awaits measuring, the measuring is the voltage drop of the device that awaits measuring, according to ohm ' S law:
R=U/I，
device under test resistance = multimeter reading xx millivolts/ampere = xx milliohms,
if the voltage measured by the multimeter exceeds the measuring range, the multimeter is dialed to the previous gear of the lowest direct-current voltage gear, and at the moment, the multimeter is used for shifting to the previous gear of the lowest direct-current voltage gear
And the resistance value of the device to be tested = xx volts/ampere = xx ohms.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116500459A (en) * | 2023-06-28 | 2023-07-28 | 中汽研汽车检验中心(常州)有限公司 | Lithium battery safety performance evaluation method and device, storage medium and electronic equipment |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102621392A (en) * | 2012-03-19 | 2012-08-01 | 吴健 | Pocket-size digital milliohmmeter |
| CN109581021A (en) * | 2018-12-21 | 2019-04-05 | 成都前锋电子仪器有限责任公司 | A kind of measurement multimeter |
| CN211652972U (en) * | 2019-12-26 | 2020-10-09 | 山西工程技术学院 | Linear scale ohmmeter based on constant current source |
-
2022
- 2022-04-25 CN CN202210447633.1A patent/CN114545055A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102621392A (en) * | 2012-03-19 | 2012-08-01 | 吴健 | Pocket-size digital milliohmmeter |
| CN109581021A (en) * | 2018-12-21 | 2019-04-05 | 成都前锋电子仪器有限责任公司 | A kind of measurement multimeter |
| CN211652972U (en) * | 2019-12-26 | 2020-10-09 | 山西工程技术学院 | Linear scale ohmmeter based on constant current source |
Non-Patent Citations (4)
| Title |
|---|
| MARK_MD: "TP4056(x) 锂电线性充电电路应用手册", 《CSDN》 * |
| 田俊杰等: "基于场效应管的恒流源设计", 《中国测试》 * |
| 老刘爱捣鼓: "省钱了！无损改装，让普通万用表变身高精度低电阻毫欧表", 《BILIBILI》 * |
| 黄国盛: "基于LM2596 的DC-DC 可调降压模块设计", 《CSDN》 * |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116500459A (en) * | 2023-06-28 | 2023-07-28 | 中汽研汽车检验中心(常州)有限公司 | Lithium battery safety performance evaluation method and device, storage medium and electronic equipment |
| CN116500459B (en) * | 2023-06-28 | 2023-08-29 | 中汽研汽车检验中心(常州)有限公司 | Lithium battery safety performance evaluation method and device, storage medium and electronic equipment |
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Application publication date: 20220527 |