CN1330967C

CN1330967C - Portable potential difference meter

Info

Publication number: CN1330967C
Application number: CNB2005100496243A
Authority: CN
Inventors: 骆乃光
Original assignee: Individual
Current assignee: Individual
Priority date: 2005-04-22
Filing date: 2005-04-22
Publication date: 2007-08-08
Anticipated expiration: 2025-04-22
Also published as: CN1673754A

Abstract

The present invention relates to a portable potential difference meter for the measurement of DC voltage, which is composed of an adjustable resistor for adjusting the work current, a setting resistor and a measurement resistor, wherein the setting resistor has the resistance of 50 omega and the work current of 5.5 mA; signals for judging whether the voltage of the setting resistor is equal to the voltage of an electronic reference source of 275 mV can be observed after amplified via an operational amplifier; the work current can be adjusted as 5.5 mA by the adjustable resistor. The portable potential difference meter has three measuring ranges and the maximum measured voltage of 2.3 V.

Description

Portable potential difference meter

Technical field:

The present invention relates to instrument that DC voltage is measured

Background technology:

In the current commercially available portable potential difference meter, highest measurement voltage can only be 1V, the above voltage of energy measurement 1V not, though certain producer has increased the electric resistance partial pressure part on the potential difference meter basis, making Range Extension is UJ59 type potential difference meter to 20V, but is two different matters with the potential difference meter of measuring with the penalty method principle after all.

Summary of the invention:

Purpose of the present invention is that design is a kind of to be measured with the penalty method principle, and the full scale energy measurement is to the multiple measuring range DC potential difference meter of 2.3V.

The present invention realizes by following technical solution: for the multirange potential difference meter, the setting resistance of its measuring resistor network and normal voltage sampling usefulness is to be connected in the work loop, because of the unsaturated standard cell electromotive force between 1.0188～1.0196V, in the work loop, need the more pressure drop of 1V so set up resistance, the electric battery nominal value is that 3V has used only surplus 2.7V old, therefore, adopt the 3V power supply, the potential difference meter of internal attachment standard battery can not be designed into to be measured more than the 1.7V.

The present invention does not adopt unsaturated standard cell in circuit, but adopt the electronics reference source of little power consumption, reference voltage is taken at below the 0.4V, sets up the pressure drop of resistance in the work loop so below 0.4V, just can be assigned to the voltage of 2.3V on the metering circuit all-in resistance.At first allow electric battery through adjustable resistance RP ₂Carry out micro-pressure regulation, voltage supply with I dish, II dish and III coil three measuring disk all-in resistances in parallel by resistance R ₆, R ₇And resistance R ₈The resistor network that the range conversion that is connected into is formed with resistance; Allow the total resistance of three measuring disk equal range transfer resistance R ₆With R ₇Sum, three range transfer resistance R simultaneously ₆, R ₇And R ₈Summation equals 10 times of three measuring disk resistance, allows three measuring disk always hinder and resistance R again ₇With R ₈Summation be resistance R ₆109 times, the working current of circuit is designed to 5.5mA, so range selector K _1-1Throw in the time of * 10 grades resistance R ₆, R ₇With R ₈The series connection back is in parallel with three measuring disk, and the electric current on the measuring disk is 5mA, designs I, when II measuring disk resistance sum is 460 Ω, at this moment can hold 2.3V equipotential (promptly can measure 2.3V voltage) as range switch K with " the unknown " _1-1Throw at * 1 o'clock three measuring disk and resistance R ₈Series connection back and the resistance R of connecting mutually ₆And R ₇Parallel connection, flowing through resistance on the measuring disk is 0.5mA, at this moment measures the upper limit and has reduced by 1/10th; When the range K switch _1-1Throw in the time of * 0.1 grade, the electric current on the measuring disk is 1 hundred-1/10th of 5.5mA, i.e. 0.05mA.Because in the time of * 0.1 grade, resistor network always hinders and has reduced in the circuit, so in the circuit of this grade, increase the resistance R of same resistance ₅, in the holding circuit between node A and the B resistance constant.Range switch K ₁Throw when " breaking " K _1-3Cut off galvanometer power supply B ₂, K _1-1Cut off the potential difference meter working power.K _1-4Cut off reference voltage power supply B ₁

Electric current is flowed through behind the resistor network, passes through resistance R ₄Get back to power supply.The setting resistance of the resistance 4 sampling usefulness that is normal voltages in the work loop, its resistance is less than 72 Ω, just can make on the setting resistance 4 pressure drop less than 0.4V.When working current equals 5.5mA in the potential difference meter, set up resistance R ₄On pressure drop equate with normal voltage EN that just in time it is to amplify the back by signal whether to observe at the zero graduation line from the galvanometer pointer, if working current departs from 5.5mA, can be by regulating resistance R P ₁And RP ₂Resistance makes working current get back to 5.5mA.

Connect " the unknown " two ends with measured by polarity, by regulating the range K switch ₁Reach I, II, III measuring disk until the galvanometer nulling, the reading of measuring disk is tested magnitude of voltage.

Description of drawings:

Accompanying drawing is the potentiometer circuit figure that is limited to 2.3V on measuring

Embodiment:

With after No. 1 battery parallel connection of 2 group of 3 joint, series connection obtains 3V left and right sides DC voltage in the drawings, through the coarse adjustment RP by 10 12 Ω series connection ₁With range of adjustment 0～15 Ω fine tuning RP ₂Node A and B in the back supply circuit.Be that measuring resistance is changed the resistor network of forming with resistance and set up resistance R with the amount limit between node A and B ₄Series circuit, what be connected with node A is measuring disk and resistance R ₆, measuring disk has three dishes, and the I dish is composed in series by 22 20 Ω; The II dish is composed in series by 10 2 Ω resistance, coiling coaxial rotation with II is its replacement dish II ', when the II dish increases by one 2 Ω resistance, replacement dish II ' deducts one 2 Ω resistance simultaneously, when guarantee measuring circuit and in total resistance constant, the III dish is a slide wire disc, and resistance is 2.2 Ω, and the total resistance of these measuring disk is 22 * 20 Ω+10 * 2 Ω+2.2 Ω=462.2 Ω.Now working current is set in 5.5mA, when switch is thrown to * 10 grades, with measuring disk parallel resistance resistance be 46.22 Ω+415.98 Ω+4159.8 Ω=4622 Ω.Its resistance is 10 times of the total resistances of measuring disk, the electric current that flows through it is 0.5mA, and flowing through the measuring disk electric current is 5mA, and I, resistance was 460 Ω when the II measuring disk was full scale, its both end voltage is 2.3V, therefore can offset (can measure) with the measured 2.3V of being voltage.This K switch ₁Throw to * 1 grade R ₆Add R ₇Resistance be 462.2 Ω, the electric current that therefore flows through measuring disk is 0.5mA, at this moment I, II dish full scale measured value reaches 230mV.Work as K switch ₁Throw to * 0.1 o'clock, the resistance value of connecting with measuring disk is that 462.2 Ω+4159.8 Ω+415.98 Ω=its resistance of 5037.98 Ω is R ₆The multiple of resistance is: 5037.98 Ω ÷, 46.22 Ω=109.The measuring disk electric current is 5.5/110mA, i.e. 0.05mA.At this moment I, II measuring disk energy measurement maximal value 23mV.* 10, * the total resistance of this resistor network in 1 o'clock is 420.1818, at * 0.1 o'clock, total resistive became 45.7998 Ω, so resistance reduced 374.382 Ω, so work as K switch ₁Throw to * 0.1 o'clock, increased resistance 374.382 Ω resistance R in the circuit ₅, resistance R ₅An end connect to set up resistance R ₄In node E, the other end and K switch _1-1* 0.1 range contact connects.

Behind the current flowing resistance network, through resistance R ₄The back arrives Node B, resistance R ₄Be the setting resistance that standard loop is used for taking a sample.

The magnitude of voltage of adjustment reference voltage EN makes EN=5.5 * R ₄* 10 ^-3(V)

When key-lifting switch K ₂Throw when " standard " resistance R ₄On voltage and the difference input operational amplifier 2 of EN voltage amplify, indicate by gauge outfit 3, if needle deflection zero graduation line illustrates that working current departs from 5.5mA, rotate coarse adjustment RP ₁And potentiometer RP ₂, make pointer return zero; Key-lifting switch is thrown in " the unknown ", by the range K switch ₁And I, II, III measuring disk suitably select, and can make to be connected on " the unknown " two ends binding post and the identical measured voltage of polarity equates.The voltage signal that whether equates is connecing through post through resistance R from measured being connected on " the unknown " anode ₁₁, R ₁₀, R ₉Voltage on measuring disk amplifies afterwards, obtains by amplifier 2.Same the scale of III dish slip, signal maximum in the time of * 10 grades, signal minimum in the time of * 0.1 grade can suitably be adjusted, the number of winning the confidence R in the time of * 10 grades ₁₁/ (R ₉+ R ₁₀+ R ₁₁), the number of winning the confidence (R in the time of * 1 grade ₁₀+ R ₁₁)/(R ₉+ R ₁₀+ R ₁₁), signal is all imported amplifier in the time of * 0.1 grade.It is by the range K switch _1-2Conversion.

Present embodiment is selected resistance R ₄=50 Ω.Reference voltage EN=275mV then, its obtains like this: the 9V battery current is by range selector K _1-4Enter current-limiting resistance R ₃After, by voltage stabilizer 1 voltage stabilizing, voltage stabilizer 1 is the sort of of 1.235V output among little power consumption voltage reference REF1004, voltage stabilizer 1 output 1.235V is through resistance R ₂And and R ₂Series connection, adjustable extent 0～10K Ω resistance R P ₃With resistance R ₁On the parallel circuit, make RP ₃Less voltage of last acquisition, and use adjustable resistance RP ₃Be fine-tuning to 275mV, resistance R ₂=15K Ω, resistance R ₁=10K.

Claims

1, a kind of portable potential difference meter that is used for dc voltage measurement, it passes through to regulate resistance R P to supply voltage ₁And RP ₂After be added in measuring resistance network and the node A and the B that set up the circuit two ends that resistance is in series, it is characterized in that node A connection is unified into the I measuring disk by 22 20 Ω resistance string, be connected into the measuring disk of II dish and the replacement dish that other 10 2 Ω resistance string are unified into the II dish by 10 2 Ω, the coaxial interlock of two dishes, one 2 Ω resistance of the every increase of II measuring disk, the replacement dish then subtracts one 2 Ω resistance, resistance is constant in the holding circuit, and the III measuring disk of one 2.2 Ω, more than become the resistance of 462.2 Ω after three dish series connection, node A connects the resistance R that resistance is 46.22 Ω again successively ₆, resistance is the resistance R of 415.9 Ω ₇, resistance is the resistance R of 4159.8 Ω ₈Coil at the 10th with replacement and link to each other, as range switch K ₁Throw at * 10 o'clock resistance R ₆And R ₇And R ₈The series connection back is in parallel with three measuring disk, range switch K ₁Throw at * 1 o'clock three measuring disk and resistance R ₈Series connection back and resistance R ₆Resistance in series R ₇Circuit be in parallel range switch K ₁Throw to * 0.1 o'clock three measuring disk and resistance R ₇And resistance R ₈Series connection back and resistance R ₆Parallel connection, * 10, * during 1 range, K switch ₁K _1-1Layer directly connects resistance R ₄In node E, at * 0.1 range switch K ₁K _1-1Layer is through 374.382 Ω resistance R ₅After flow to node E, electric current flows through behind the measuring resistance network to node E from node A, passes through the setting resistance R less than 72 Ω again ₄After flow to the Node B end.

2, a kind of portable potential difference meter that is used for dc voltage measurement according to claim 1, the resistance that it is characterized in that setting up resistance is 50 Ω, its normal voltage is 9V battery B ₁Through current-limiting resistance R ₃The back is by little power consumption voltage reference REF1004[1] 1.235V is provided voltage standard, be the resistance R of 15K Ω again by resistance ₂Be connected on the adjustable resistance RP of range of adjustment 0～10K Ω ₃With resistance be 10K Ω resistance R ₁Dividing potential drop on the parallel resistance is regulated RP ₃, make reference voltage EN=275mV, by amplifier [2] and gauge outfit [3] to setting up resistance R ₄On voltage whether be that 275mV carries out verification.