CN1793955A - Laboratory potential difference meter having five measuring discs three measuring range - Google Patents

Laboratory potential difference meter having five measuring discs three measuring range Download PDF

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Publication number
CN1793955A
CN1793955A CN 200510062258 CN200510062258A CN1793955A CN 1793955 A CN1793955 A CN 1793955A CN 200510062258 CN200510062258 CN 200510062258 CN 200510062258 A CN200510062258 A CN 200510062258A CN 1793955 A CN1793955 A CN 1793955A
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China
Prior art keywords
resistance
measuring disk
bracket panel
range
dish
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CN 200510062258
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Chinese (zh)
Inventor
骆乃光
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Individual
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Individual
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Priority to CN 200510062258 priority Critical patent/CN1793955A/en
Publication of CN1793955A publication Critical patent/CN1793955A/en
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Abstract

A three-range potential difference meter with five measuring discs in laboratory type is prepared as using 20x 80 omega as the first measuring disc, 9x 17.6 omega as the second and the third measuring discs, 10x 1.76 omega as the fourth and fifth measuring discs; using conductive wire to connect resistances on all measuring discs between two measuring end buttons to exclude influence of contact resistance variation and thermo voltage from measuring switch on measuring result and using integer power of one or two digit number multiplying by ten as value of resistance used on range changeover.

Description

Five measuring disk, three range Laboratary type potential difference meters are arranged
Technical field
The present invention relates to measure the instrument of DC voltage.
Background technology
The potential difference meter of current production, when measuring disk has three when above, measure between terminal for two and have switch contact resistance and variation, therefore, even working current is little of 0.1mA, the silver-bearing copper compound substance is not only adopted in the brush of switch and contact, contact area is also done very greatly, variation is brought influence when reducing measuring switch stepping switching, this just makes the instrument volume become big, nonetheless, can not make potential difference meter resolution little to 0.1 μ v, the thermoelectrical potential that also has switch in addition with contact variable thermoelectric potential influence.
Summary of the invention
The problem to be solved in the present invention is, when the step switch that is used for measure portion in the potential difference meter has five, and contact resistance and variation that the measuring switch stepping is switched, the switch thermoelectrical potential does not influence measurement result, makes instrumental resolution reach 0.1 μ v.When range was changed, range conversion was the resistance that one digit number or two figure places are taken advantage of 10 integral number power with resistance.
Technical scheme of the present invention is such: working current is regulated resistance R P 1, RP 2, RP 3And be used to reduce the fixed resistance R of supply voltage 0, sampling is with setting up resistance and temperature compensation dish RP during to standard 4And five resistor networks of measuring on the step switch are connected in the potential difference meter work loop, and working current is 1.25mA when standardization; It is characterized in that first step dish is made up of I measuring disk and I ' replacement dish, 0～20 indicating value is provided, two resistance above the dish are 20 * 80 Ω, second step disc is by " 0 ", non-resistance between " 1 " two contacts, there is the II measuring disk of 9 * 17.6 Ω resistance 1～10 contact, II ' the replacement dish of 10 * 17.6 Ω reaches and is not connected to resistance, 0 contact is independent, the II that all the other contacts link to each other " the bracket panel composition; the 3rd step disc is by " 9 "; non-resistance between " 10 " two contacts; be the III measuring disk of 9 * 17.6 Ω resistance between 0～9 contact; III ' the replacement dish of 10 * 0.176 Ω and the 10th III that all the other each points of independence connect " the bracket panel composition, the 4th step disc is by all being that the IV measuring disk of 10 * 0.176 Ω resistance and IV ' replacement dish and resistance are the IV of 10 * 0.088 Ω " bracket panel forms; the 5th step disc is the V measuring disk of 10 * 0.176 Ω by resistance; V ' replacement dish and resistance are the V of 10 * 0.088 Ω " bracket panel forms, except that first step disc, the replacement dish of all the other four step discs and the brush of measuring disk are connected to each other; I ' replacement dish brush is connected in the metering circuit positive pole, and I ' replacement is coiled at the 20th and connected 122.232 Ω resistance R 1The back connects IV " bracket panel the 10th point, IV " 0 connection of bracket panel II " bracket panel 0 point; IV " the bracket panel brush connects II " contact of bracket panel except that 0 o'clock, II " the bracket panel brush is divided into two-way, and one the tunnel through 174.24 Ω resistance R 2Back and IV " replacement coils at the 10th and is connected, and another road connects II ' replacement and coils the 10th point, and II measuring disk the 1st o'clock is through 15.84 Ω resistance R 3Back IV measuring disk the 10th connection, 0 of 0 of II measuring disk and IV measuring disk all with 168.888 Ω resistance R 4Connect at one end resistance R 4The other end is connected with 0 of I measuring disk; 0 on I ' replacement dish connects 18111.12 Ω resistance R 5Back and V " 0 of bracket panel is connected; V " the 10th connection of bracket panel III " bracket panel the 10th point; V " the bracket panel brush connects III ' bracket panel all the other each contacts except that the 10th contact, III " the bracket panel brush is divided into two branch roads, the one tunnel through 174.24 Ω resistance R 6The back connects 0 point of V ' replacement dish, and another road connects III ' replacement and coils 0 point, and the 9th of III measuring disk connects 15.84 Ω resistance R 7The back is connected with 0 of V measuring disk, and the 10th of III measuring disk measured at the 10th with the V dish and all be connected with the 20th of I measuring disk; The I ' replacement dish brush and 200 Ω resistance r 1Be connected in parallel on potential difference meter and measure partly positive pole, resistance r 1The other end connect four blade three throw switch K 1-1* 1 range contact, K 1-2* 1 range contact and K 1-1* 10 range contacts connect K 1-3* 1620 Ω resistance r are passed through in 1 range contact 2With K 1-3* connection of 10 range contacts, this contact is connected the negative pole of potential difference meter metering circuit, four blade three throw switch K 1-1* 10 range contacts connect the 1st measuring disk brush; 20 Ω resistance r 3Be connected resistance r with the I ' replacement dish brush 3The other end connect K 1-1* 0.1 range contact, K 1-2* 180 Ω resistance r are passed through in 0.1 range contact 4With K 1-1* 10 range contacts connect K 1-3* touch by 160.2 Ω resistance r with * 1 range 0.1 range contact 5Connect four blade three throw switch K 1-1, K 1-2, K 1-3Three normally closed contact short circuits; Two terminals of measuring disk are anodal to be connected with the 10th of II measuring disk, and negative pole is by galvanometer change-over switch K 2Be connected with 0 of III measuring disk.
By above technical scheme, the measuring disk that five step discs are used for measure portion connects with lead, contact resistance and variation, not in measuring the loop, the just potential difference meter work loop of influence always hinders, because total resistance resistance is very big, so variation can be ignored, the thermoelectric potential influence of several μ V be supply voltage, supply voltage be the volt, how many μ V are thermoelectrical potential be, both differ 10 the 6 power orders of magnitude, and therefore influence can be ignored, even so, even contact resistance variation and thermoelectrical potential are big to the degree of can not ignore, can be by standard is adjusted RP 3Resistance obtain revising, zero potential can increase between V measuring disk and the I measuring disk lead resistance and revise, Just because of this, reduced requirement to switch, after adopting small-sized measurement step switch, it is many that whole instrument overall dimensions reduce, and this instrumental resolution can obtain good repeatability when being 0.1 μ V.Because the range conversion is that one digit number or double figures are taken advantage of 10 integral number power with resistance, available interim standard resistance is revised with resistance range conversion, has improved the accuracy of potential difference meter range ratio.
Description of drawings
Accompanying drawing is a principle of the invention circuit.
Embodiment
In the drawings, by " U x" anodal through each measuring disk, pass through change-over switch K again 2To " U x" negative pole is to measure the loop, by positive source through measuring step switch to setting resistance R N and temperature compensation dish RP 4, arrive resistance R then 0, adjustable resistance RP 3, RP 2And RP 1After, getting back to power cathode is the work loop, anodal through change-over switch K from standard cell EN 2, to setting up resistance R N and temperature compensation dish RP 4, be standard loop to the standard cell negative pole again.When five dishes are all thrown " 0 ", left side resistance equals 1980 Ω between two brushes of first step disc, and the right resistance equals 19800 Ω, and total resistance is 1800 Ω between two brushes of first step disc, therefore 10/1 on the left side of total current flows between two brushes of first dish, and 1/11 flows on the right.When second dish threw at 0, second dish equated that with the 4th dish partly resistance in parallel when the 4th dish was thrown different indicating value, the circuit resistance was constant.When second dish is not thrown 0 the time, the 4th dish is thrown different indicating values, the circuit resistance is not having IV " resistance changes during bracket panel; stepping of the 4th every increase of dish; the circuit resistance can increase half resistance of each stepping resistance; for the total resistance of holding circuit constant; at IV " in the bracket panel each stepping reduce same resistance, when second step disc throws 0, the resistance minimum, at this moment allow IV " bracket panel resistance all seals in circuit, makes the circuit resistance constant, in like manner; the right circuit is provided with III " bracket panel and V " bracket panel is that to switch to the total resistance of any indicating value holding circuit constant for the 3rd step disc and the 5th step disc switch; because first dish is made up of resistance identical measuring disk and replacement dish, so what indicating value no matter five dishes throw, circuit always hinders constant;
When * 1 range, resistance is 1/9 resistance r of resistance between two brushes of first step disc 1In parallel with two brushes, the electric current that flows through between two brushes of first step disc is reduced to * 1/10 during 10 ranges, the amount of making limit is reduced to 1/10, resistance r 1With resistance value is reduced after two brushes are in parallel, so seal in resistance r in the potentiometer circuit 2Keep total resistance value constant.At * 0.1 range, total resistance resistance in series r between two brushes of first step disc 4After, with 99 times to resistance r 3Resistance and resistance r 3Parallel connection, make to flow through the measuring disk electric current and be reduced to * 10 ranges 1/100, the amount of making limit is reduced to * 10 ranges 1/100, parallel connection reduces resistance, advances resistance r by series connection in potentiometer circuit 5Add resistance r 2Keep total resistance constant;
The potential difference meter working current is 1.25mA, left side electric current 12.5/11mA between two brushes of first step disc, the right electric current is 1.25/11mA, left side electric current flows through II " is divided into two equal branch roads; when second dish threw at 0, two branch roads that flow through II measuring disk and IV measuring disk separated, when the II measuring disk does not throw 0; flow through II measuring disk branch current and all flow through IV measuring disk resistance, and 10 resistance of IV measuring disk add resistance R behind the bracket panel brush 3Play the effect of the 1st resistance of II measuring disk, when the IV measuring disk is thrown n 4The time, n 4Though～0 ohmically electric current is exactly a left side electric current, can regard two branch currents as and be formed by stacking, can be when therefore calculating with separate computations; In like manner, the right electric current is thrown n at the 5th dish between two brushes of first step disc 5The time, 10～n 5Electric current regard the stack of two branch currents as, take separate computations during calculating.Sampling is 814.4 Ω with setting up resistance R N resistance, when the working current standardization, setting up ohmically pressure drop is 1.018V, the potential difference meter calibrating is carried out in constant temperature enclosure, standard electromotive force of the cell is 1.0186V in the time of 20 ℃, during 20 ℃ of temperature departures, every degree can compensate by-40 μ V, temperature compensation dish RP 4Be 20 * 0.04 Ω, satisfy the national standard of each step value compensation 50 μ V of 0.02 grade of potential difference meter.
The minimum calibration of thermometer on the standard cell EN is 0.1 ℃, after according to temperature value the temperature compensation dish being regulated, and K switch 2Point to the right, regulate adjustable resistance RP 1, RP 2And PR 3After, make galvanometer G nulling, potential difference meter working current standardization at this moment, at this moment, the I measuring disk is thrown n 1, the I measuring disk is thrown n 1, the II measuring disk is thrown n 2, the III measuring disk is thrown n 3The IV measuring disk is thrown n 4, the V measuring disk throws n 5
Ux＝12.5/22×17.6n 2+12.5/22×0.176n 4+12.5/11×(160+8.8+0.088)+12.5/11×80n 1-1.25/11×(20-n 1)×80-1.25/22×(10-n 5)×0.176-1.25/22×(10-n 3)×17.6
＝10n 2+0.4n 4+2000/11+10+0.1+1000n 1/11-2000/11+100n 1/11-0.1+0.01n 5-10+1n 3(mv)
＝100n 1+10n 2+1n 3+0.1n 4+0.01n 5(mv)
More than be * five measuring disk indicating values of 10 ranges, when * 0.1 range, five measuring disk indicating values are expressed as n 1+ 0.1n 2+ 0.01n 3+ 0.001n 4+ 0.0001n 5(mv).
The potential difference meter operating voltage is 4.5V, because the every joint stable electrical of dry cell kinetic potential between 1.4V～1.65V, all can be adjusted to standard state to the potential difference meter working current for realizing supply voltage at 4.2V～4.95V, gets fixed resistance R 0=744 Ω, adjustable resistance RP 1=20 * 30 Ω, RP 2Be 20 * 1.6 Ω, RP 3Be 20 * 0.084 Ω.
Four blade double throw switch K 1-4Right * 10, * 1 range carries out the decay of input signal, enters amplifier at the whole signals of * 0.1 range, is (the R of whole signals at * 1 range input signal 10+ R 9)/(R 8+ R 9+ R 10), when * 10 ranges, input signal is the R of whole signals 10/ (R 8+ R 9+ R 10) the diode D of the positive and negative connection of amp.in 1And D 2Be used for input protection, two integrated amplifier OPA128 carry out the differential output of differential input, feedback resistance R 11With R 12Equate, get 1M Ω here, resistance R 13Get 200 Ω, amplified signal shows with reometer G.

Claims (1)

  1. A kind of have five measuring disk, three range Laboratary type potential difference meters, and it has working current to regulate resistance R P 1, RP 2, RP 3And be used to reduce the fixed resistance R of supply voltage 0, sampling is with setting up resistance and temperature compensation dish RP during to standard 4And five resistor networks of measuring on the step switch are connected in the potential difference meter work loop, and working current is 1.25mA when standardization; It is characterized in that first step dish is made up of I measuring disk and I ' replacement dish, 0～20 indicating value is provided, two resistance above the dish are 20 * 80 Ω, second step disc is by " 0 ", non-resistance between " 1 " two contacts, there is the II measuring disk of 9 * 17.6 Ω resistance 1～10 contact, II ' the replacement dish of 10 * 17.6 Ω reaches and is not connected to resistance, 0 contact is independent, the II that all the other contacts link to each other " the bracket panel composition; the 3rd step disc is by " 9 "; non-resistance between " 10 " two contacts; be the III measuring disk of 9 * 17.6 Ω resistance between 0～9 contact; III ' the replacement dish of 10 * 0.176 Ω and the 10th III that all the other each points of independence connect " the bracket panel composition, the 4th step disc is by all being that the IV measuring disk of 10 * 0.176 Ω resistance and IV ' replacement dish and resistance are the IV of 10 * 0.088 Ω " bracket panel forms; the 5th step disc is the V measuring disk of 10 * 0.176 Ω by resistance; V ' replacement dish and resistance are the V of 10 * 0.088 Ω " bracket panel forms, except that first step disc, the replacement dish of all the other four step discs and the brush of measuring disk are connected to each other; I ' replacement dish brush is connected in the metering circuit positive pole, and I ' replacement is coiled at the 20th and connected 122.232 Ω resistance R 1The back connects IV " bracket panel the 10th point, IV " 0 connection of bracket panel II " bracket panel 0 point; IV " the bracket panel brush connects II " contact of bracket panel except that 0 o'clock, II " the bracket panel brush is divided into two-way, and one the tunnel through 174.24 Ω resistance R 2Back and IV " replacement coils at the 10th and is connected, and another road connects II ' replacement and coils the 10th point, and II measuring disk the 1st o'clock is through 15.84 Ω resistance R 3Back IV measuring disk the 10th connection, 0 of 0 of II measuring disk and IV measuring disk all with 168.888 Ω resistance R 4Connect at one end resistance R 4The other end is connected with 0 of I measuring disk; 0 on I ' replacement dish connects 18111.12 Ω resistance R 5Back and V " 0 of bracket panel is connected; V " the 10th connection of bracket panel III " bracket panel the 10th point; V " the bracket panel brush connects III ' bracket panel all the other each contacts except that the 10th contact, III " the bracket panel brush is divided into two branch roads, the one tunnel through 174.24 Ω resistance R 6The back connects 0 point of V ' replacement dish, and another road connects III ' replacement and coils 0 point, and the 9th of III measuring disk connects 15.84 Ω resistance R 7The back is connected with 0 of V measuring disk, and the 10th of III measuring disk measured at the 10th with the V dish and all be connected with the 20th of I measuring disk; The I ' replacement dish brush and 200 Ω resistance r 1Be connected in parallel on potential difference meter and measure partly positive pole, resistance r 1The other end connect four blade three throw switch K 1-1* 1 range contact, K 1-2* 1 range contact and K 1-1* 10 range contacts connect K 1-3* 1620 Ω resistance r are passed through in 1 range contact 2With K 1-3* connection of 10 range contacts, this contact is connected the negative pole of potential difference meter metering circuit, four blade three throw switch K 1-1* 10 range contacts connect the 1st measuring disk brush; 20 Ω resistance r 3Be connected resistance r with the I ' replacement dish brush 3The other end connect K 1-1* 0.1 range contact, K 1-2* 180 Ω resistance r are passed through in 0.1 range contact 4With K 1-1* 10 range contacts connect K 1-3* touch by 160.2 Ω resistance r with * 1 range 0.1 range contact 5Connect four blade three throw switch K 1-1, K 1-2, K 1-3Three normally closed contact short circuits; Two terminals of measuring disk are anodal to be connected with the 10th of II measuring disk, and negative pole is by galvanometer change-over switch K 2Be connected with 0 of III measuring disk.
CN 200510062258 2005-12-28 2005-12-28 Laboratory potential difference meter having five measuring discs three measuring range Withdrawn CN1793955A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN 200510062258 CN1793955A (en) 2005-12-28 2005-12-28 Laboratory potential difference meter having five measuring discs three measuring range

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Application Number Priority Date Filing Date Title
CN 200510062258 CN1793955A (en) 2005-12-28 2005-12-28 Laboratory potential difference meter having five measuring discs three measuring range

Publications (1)

Publication Number Publication Date
CN1793955A true CN1793955A (en) 2006-06-28

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Country Status (1)

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CN (1) CN1793955A (en)

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