CN100375901C - Three-measuring range DC potential difference meter with five's place reading utilizing, shunt branch - Google Patents
Three-measuring range DC potential difference meter with five's place reading utilizing, shunt branch Download PDFInfo
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- CN100375901C CN100375901C CNB2005100622710A CN200510062271A CN100375901C CN 100375901 C CN100375901 C CN 100375901C CN B2005100622710 A CNB2005100622710 A CN B2005100622710A CN 200510062271 A CN200510062271 A CN 200510062271A CN 100375901 C CN100375901 C CN 100375901C
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Abstract
The present invention relates to a DC potential difference meter with a five-digit reading number, which uses a shunting branch circuit, is converted by three measuring ranges and is used for measuring the DC voltage. The DC potential difference meter has the three measuring ranges and is composed of three measuring discs of 20*100 omega, 9*22 omega and 10*2.2 omega, and a slide wire disc of 0 omega to 12.1 omega. The DC potential difference meter provides the five-digit reading number. All resistors for measuring are directly connected by conducting wires, and the contact resistance and the variation of a measuring stepping switch are excluded out of a measuring result. When the minimum resolution is equal to 0.1 muV, the DC potential difference meter also has the good repeatability. The integer power of a one-digit number or a two-digit number multiplied with ten is used as a resistance value of the resistor used for the conversion of the meausring ranges.
Description
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 being used for measure portion in the potential difference meter three step discs and a slide wire disc arranged, 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: the adjustable resistance RP that regulates 20 * 37 Ω of working current size
1And the adjustable resistance RP of range of adjustment between 0～41 Ω
2, be used to reduce by 480 Ω fixed resistance R of supply voltage
0The resistor network that 1018 Ω of sampling usefulness set up on resistance R N and three step discs, the two slide wire disc during to standard is connected in the potential difference meter work loop, when the voltage drop on the 1018 Ω setting resistance R N equated with the potential difference meter internal attachment standard, its working current equaled 1mA; First step disc is made up of I measuring disk that 20 * 100 Ω are respectively arranged and the I ' replacement dish, second step disc is by non-resistance between the 0th and the 1st, these two contacts disconnect, all the other contacts are by the II measuring disk of 9 * 22 Ω of resistance connection, 10 * 22 Ω the II ' replacement dishes are arranged and be not welded with resistance, the 0th independence, the II that all the other contacts connect " bracket panel forms; the 3rd step disc is by being all III measuring disk and the III ' replacement dish that 10 * 2.2 Ω resistance form and the III that 10 * 1.1 Ω resistance are arranged " bracket panel forms, the 4th dish is two slide wire discs, two slide wire resistance resistances all are 12.1 Ω, wherein one is IV measuring disk slip, another root is an IV ' replacement dish slip, the index dial of two slide wire discs indicates 10 big lattice of 0～100 one indicating value, every big lattice have 10 little lattice, the corresponding resistance of every big lattice is 1.1 Ω, from the 0.55 Ω resistance wire at slide wire resistance silk top " 1 " in two slide wire discs inside, stretching out two slide wire disc parts at first is 5 little lattice, the back is to have 0,1,2 ... 10 big lattice of 100 one scale values have 105 little lattice; Except that first step disc, the brush of the measuring disk on all the other each dishes oneself dish is connected with the brush of replacement dish; The I ' replacement is coiled at the 20th and is connected III by 647.9 Ω resistance R 1 " bracket panel the 10th point; III " the 0th of bracket panel connect II " bracket panel the 0th point; and III " bracket panel brush and II " bracket panel is connected all the other contacts except that the 0th; II " bracket panel brush one tunnel connects the II ' replacement and coils the 10th point, and 198 Ω resistance R are passed through on another road
2Coiling at the 10th with the III ' replacement is connected, the 1st of II measuring disk connects III measuring disk the 10th point, it is that 201.1 Ω resistance R, 3 backs are connected with the 0th of I measuring disk that the 0th of II measuring disk is connected resistance jointly with the 0th of III measuring disk, the 20th of I measuring disk connects IV measuring disk the 10th point, and the IV ' replacement dish top connects 27687.9 Ω resistance R
4The back is coiled at the 0th with the I ' replacement and is connected; The I ' replacement dish brush and 300 Ω resistance r
1Be connected in parallel on potential difference meter measure portion 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* 2430 Ω resistance r are passed through in 1 range contact
2With K
1-3* 10 range contacts connect, and are connected on the negative pole of potential difference meter metering circuit after the connection again, four blade three throw switch K
1-1* 10 range contacts connect the 1st measuring disk brush; 30 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* 270 Ω resistance r are passed through in 0.1 range contact
4With K
1-1* 10 range contacts connect K
1-3* 240.3 Ω resistance r are passed through with * 1 range contact in 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 junction 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 IV measuring disk line top.
By above technical scheme, the measuring disk that three step discs and slide wire disc 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
2Resistance obtain revising, zero potential can obtain revising by adjusting the slide wire disc zero-bit, or increases between IV measuring disk and the I measuring disk lead resistance and revise, so 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
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 RP
3, arrive resistance R then
0, adjustable resistance 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 RP
3, be standard loop to the standard cell negative pole again.When four dishes are all thrown " 0 ", left side resistance is 2970 Ω between two brushes of first step disc, and the right resistance equals 29700 Ω, and total resistance is 2700 Ω between two brushes of first step disc, therefore 10/11 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 3rd dish partly resistance in parallel when the 3rd dish was thrown different indicating value, the circuit resistance was constant.When second dish is not thrown 0 the time, the 3rd dish is thrown different indicating values, the circuit resistance is not having III " resistance changes during bracket panel; the 3rd dish every increase stepping, circuit resistance can increase half resistance of each stepping resistance, for the total resistance of holding circuit constant; each stepping reduces same resistance in the 3rd bracket panel; resistance minimum when second step disc throws 0, at this moment allows the III ' bracket panel resistance all seal in circuit, makes the circuit resistance constant.Because first dish and the 4th dish are formed by resistance identical measuring disk and replacement dish, so what indicating value no matter four 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.
Basic range potential difference meter working current is 1mA, left side electric current 10/11mA between two brushes of first step disc, the right electric current is 1/11mA, left side electric current flows through II " is divided into two equal branch roads; when second dish throws at 0; two branch roads that flow through II measuring disk and III measuring disk separate; when the II measuring disk does not throw 0; flow through II measuring disk branch current and all flow through III measuring disk resistance; 10 resistance of III measuring disk play the effect of the 1st resistance of II measuring disk, when the III measuring disk is thrown n behind the bracket panel brush
3The time, n
3Though～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;
The 1mA working current is to determine like this, at " U
x" two of two ends measure terminals and connect normal voltage near full scale, K switch by polarity
2Throw to the left side, the measuring disk indicating value is identical with standard voltage value, regulates resistance R P by regulating working current
1And RP
2, make the galvanometer nulling, again with K switch
2Throw to the right, sampling is 1018 Ω with the resistance of setting up resistance R N, and 0～2 Ω adjustable resistance RP has connected
3, regulate RP
3, make galvanometer nulling once more, again with K switch
2Throw to the left side, regulate RP
2Make the galvanometer nulling, again with K switch
2Throw to the right and regulate RP
3Make the galvanometer nulling, when switch points to the left side and the right and do not regulate the equal nulling of galvanometer, the standardization of potential difference meter working current is described, promptly set up ohmically pressure drop and equate, at this moment with RP with the electromotive force of unsaturated standard cell EN
3Locking, this potential difference meter is from now on just as standard.After the working current standardization, the I measuring disk is thrown n
1, the II measuring disk is thrown n
2, the III measuring disk is thrown n
3, the IV measuring disk is thrown n
4, K switch
2Throw to the left side, be positioned at this moment that voltage is between two terminals of measurement:
Ux＝5/11×22n
2+5/11×2.2n
3+10/11×(200+1.1)+10/11×100n
1-1/11×(20-n
1)×100-1/11×(10-n
4)×1.1(mv)
＝10n
2+n
3+2000/11+1+1000n
1/11-2000/11+100n
1/11-1+0.1n
4(mv)
＝100n
1+10n
2+n
3+0.1n
4(mv)
More than be * 10 range four measurement disks indicating values, when * 0.1 range, the four measurement disks indicating value is expressed as n
1+ 0.1n
2+ 0.01n
3+ 0.001n
4(mv), above n
4Calculating by big lattice resistance, is 0.1 μ v at the every little lattice resolution of * 0.1 range therefore.
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=480 Ω, adjustable resistance RP
1=20 * 37 Ω, RP
2Be 0～41 Ω.
Four blade three 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 and resistance R
5, resistance R
6, resistance R
7The amplifying circuit of forming the differential output of differential input amplifies signal, and the signal after the amplification shows with reometer G.
Claims (1)
1. three measuring ranges DC potentiometer that has five digit reading to adopt diverter branch, it has the adjustable resistance RP of 20 * 37 Ω that regulate the working current size
1And the adjustable resistance RP of range of adjustment between 0～41 Ω
2, be used to reduce by 480 Ω fixed resistance R of supply voltage
0The resistor network that 1018 Ω of sampling usefulness set up on resistance R N and three step discs, the two slide wire disc during to standard is connected in the potential difference meter work loop, when the voltage drop on the 1018 Ω setting resistance R N equated with the potential difference meter internal attachment standard, its working current equaled 1mA; It is characterized in that first step disc is made up of I measuring disk that 20 * 100 Ω are respectively arranged and the I ' replacement dish, second step disc is by non-resistance between the 0th and the 1st, these two contacts disconnect, all the other contacts are by the II measuring disk of 9 * 22 Ω of resistance connection, 10 * 22 Ω the II ' replacement dishes are arranged and be not welded with resistance, the 0th independence, the II that all the other contacts connect " bracket panel forms; the 3rd step disc is by being all III measuring disk and the III ' replacement dish that 10 * 2.2 Ω resistance form and the III that 10 * 1.1 Ω resistance are arranged " bracket panel forms, the 4th dish is two slide wire discs, two slide wire resistance resistances all are 12.1 Ω, wherein one is IV measuring disk slip, another root is an IV ' replacement dish slip, the index dial of two slide wire discs indicates 10 big lattice of 0～100 one indicating value, every big lattice have 10 little lattice, the corresponding resistance of every big lattice is 1.1 Ω, from the 0.55 Ω resistance wire at slide wire resistance silk top " 1 " in two slide wire discs inside, stretching out two slide wire disc parts at first is 5 little lattice, the back is to have 0,1,2 ... 10 big lattice of 100 one scale values have 105 little lattice; Except that first step disc, the brush of the measuring disk on all the other each dishes oneself dish is connected with the brush of replacement dish; The I ' replacement coils at the 20th by 647.9 Ω resistance R
1Connect III " bracket panel the 10th point; III " the 0th of bracket panel connect II " bracket panel the 0th point; and III " bracket panel brush and II " bracket panel is connected all the other contacts except that the 0th; II " bracket panel brush one tunnel connects the II ' replacement and coils the 10th point, and 198 Ω resistance R are passed through on another road
2Coil at the 10th with the III ' replacement and be connected, the 1st of II measuring disk connects III measuring disk the 10th point, and it is 201.1 Ω resistance R that the 0th of II measuring disk is connected resistance jointly with the 0th of III measuring disk
3The back is connected with the 0th of I measuring disk, and the 20th of I measuring disk connects IV measuring disk the 10th point, and the IV ' replacement dish top connects 27687.9 Ω resistance R
4The back is coiled at the 0th with the I ' replacement and is connected; The I ' replacement dish brush and 300 Ω resistance r
1Be connected in parallel on potential difference meter measure portion 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* 2430 Ω resistance r are passed through in 1 range contact
2With K
1-3* connection of 10 range contacts, be connected on potential difference meter measure portion negative pole after the connection again, four blade three throw switch K
1-1* 10 range contacts connect I measuring disk brush; 30 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* 270 Ω resistance r are passed through in 0.1 range contact
4With K
1-1* 10 range contacts connect K
1-3* 240.3 Ω resistance r are passed through with * 1 range contact in 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 junction 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 IV measuring disk slip top.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB2005100622710A CN100375901C (en) | 2005-12-28 | 2005-12-28 | Three-measuring range DC potential difference meter with five's place reading utilizing, shunt branch |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB2005100622710A CN100375901C (en) | 2005-12-28 | 2005-12-28 | Three-measuring range DC potential difference meter with five's place reading utilizing, shunt branch |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1811470A CN1811470A (en) | 2006-08-02 |
| CN100375901C true CN100375901C (en) | 2008-03-19 |
Family
ID=36844509
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNB2005100622710A Withdrawn - After Issue CN100375901C (en) | 2005-12-28 | 2005-12-28 | Three-measuring range DC potential difference meter with five's place reading utilizing, shunt branch |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN100375901C (en) |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0280303A2 (en) * | 1987-02-26 | 1988-08-31 | Veb Kombinat Wolle Und Seide | Method and circuit for the automatic measuring of direct currents |
| CN2035080U (en) * | 1988-04-11 | 1989-03-29 | 付狄鹏 | Electric difference temperature meter |
| CN1425923A (en) * | 2001-12-08 | 2003-06-25 | 骆乃光 | Multiple measuring range DC potential difference meter |
-
2005
- 2005-12-28 CN CNB2005100622710A patent/CN100375901C/en not_active Withdrawn - After Issue
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0280303A2 (en) * | 1987-02-26 | 1988-08-31 | Veb Kombinat Wolle Und Seide | Method and circuit for the automatic measuring of direct currents |
| CN2035080U (en) * | 1988-04-11 | 1989-03-29 | 付狄鹏 | Electric difference temperature meter |
| CN1425923A (en) * | 2001-12-08 | 2003-06-25 | 骆乃光 | Multiple measuring range DC potential difference meter |
Non-Patent Citations (2)
| Title |
|---|
| 直流电位差计的三个回路. 李得亨.计量与测试技术，第1期. 2000 * |
| 高精度双量程桥式电位差计. 刘浙华.实用测试技术，第3期. 1995 * |
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| Publication number | Publication date |
|---|---|
| CN1811470A (en) | 2006-08-02 |
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