CN100386634C - Two-measuring range DC potential difference meter - Google Patents
Two-measuring range DC potential difference meter Download PDFInfo
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- CN100386634C CN100386634C CNB2005100623751A CN200510062375A CN100386634C CN 100386634 C CN100386634 C CN 100386634C CN B2005100623751 A CNB2005100623751 A CN B2005100623751A CN 200510062375 A CN200510062375 A CN 200510062375A CN 100386634 C CN100386634 C CN 100386634C
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- resistance
- measuring disk
- measuring
- iii
- replacement
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Abstract
The present invention relates to a two-measuring range direct current potential difference meter used for measuring direct current voltage. The present invention has two measuring ranges and is composed of four measuring discs as 20*8 omega, 10*0.88 omega, 9*1.76 omega and 10*0.176 omega. All measuring resistors are directly connected by conducting wires. Contact resistance and variation of a measuring stepping switch are excluded out of a measuring result. When the minimum resolution is equal to 1 muV, good repeatability can also be obtained. An integer power of a one-digit number multiplied by ten is used as a resistance value of a resistor used for measuring range conversion.
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 the measuring switch stepping and switching, and this just makes the instrument volume become big, 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 four step discs arranged, contact resistance and variation that the measuring switch stepping is switched, the switch thermoelectrical potential does not influence measurement result, when range was changed, range conversion was the resistance that one digit number is taken advantage of 10 integral number power with resistance.
Technical scheme of the present invention is such: it has the adjustable resistance RP that regulates the working current size
1And RP
2, be used to reduce the fixed resistance R of supply voltage
0, the 815 Ω setting resistance R N of sampling usefulness and range of adjustment are at the adjustable resistance RP of 0~1 Ω during to standard
3, the resistor network that reaches on four step discs is connected in the potential difference meter work loop, and when the voltage drop on the setting resistance R N equated with the potential difference meter internal attachment standard, its working current equaled 1.25mA; Signal amplifies employing two OPA128, resistances and all equals 1M Ω resistance R
1With resistance R
2, 200 Ω resistance R
3The amplifying circuit of forming the differential output of differential input, input end is with the diode D of positive and negative connection
1And D
2Protect, amplified signal shows by reometer G, resistance R
4Both end voltage is made amplifier signal voltage; First step disc is made up of I measuring disk that 20 * 8 Ω are respectively arranged and the I ' replacement dish, second step disc is made up of II measuring disk that 10 * 0.88 Ω are respectively arranged and the II ' replacement dish, the 3rd step disc is by " 9 ", non-resistance between " 10 " two contacts, these two contacts disconnect, all the other contacts are by the III measuring disk of 9 * 1.76 Ω resistance of resistance connection, 10 * 1.76 Ω the III ' replacement dishes are arranged and be not welded with resistance, the 10th independence, the III that all the other contacts connect " bracket panel forms; the 4th step disc is by being all IV measuring disk and the IV ' replacement dish that 10 * 0.176 Ω resistance form and the IV that 10 * 0.088 Ω resistance are arranged " bracket panel forms, except that first step disc, the brush of the measuring disk on all the other step discs oneself dish is connected with the brush of replacement dish; The 1st ' replacement is coiled and was connected the II ' replacement by 12.232 Ω resistance at the 20th o'clock and coil the 10th point, after connecting one 16.968 Ω resistance, the 0th of II measuring disk be connected with the 0th of I measuring disk, the I ' replacement is coiled at the 0th and is connected IV after connecting one 1810.32 Ω resistance " bracket panel the 0th point; IV " the 10th of bracket panel and III " the 10th of bracket panel be connected; IV " the bracket panel brush connects III " bracket panel all contacts except that the 10th contact; and III " bracket panel brush one tunnel connects the III ' replacement and coils the 0th point, another road is coiled at the 0th with the IV ' replacement after by 15.84 Ω resistance and is connected, and the 10th of III measuring disk directly is connected with the 20th of I measuring disk; The 9th of III measuring disk connects IV measuring disk the 0th point, and the 10th of IV measuring disk is connected with the 20th of I measuring disk; The I ' replacement dish brush and 20 Ω resistance r
1Be connected in parallel on potential difference meter measure portion positive pole, resistance r
1The other end connect dpdt double-pole double-throw (DPDT) range selector K
1Layer * 0.1 range contact, a left side, right layer * 0.1 range contact and I measuring disk brush all with double-point double-throw switch K
1Left side layer * 1 range contact connection, 162 Ω resistance r
2One end connects K
1Right layer * 0.1 range contact, the other end connects K
1Right layer * 1 range contact, K
1Right layer * 1 range contact is connected on potential difference meter measure portion negative pole, double-point double-throw switch K
1Left side layer and right layer normally closed contact short circuit, potential difference meter is used to connect measured U
xTwo terminals, anodal terminal is connected with the 10th of II measuring disk, and the negative pole terminal is by galvanometer change-over switch K
2Be connected with 0 of III measuring disk.
By above technical scheme, the measuring disk that four 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 be revised by increasing between IV measuring disk and the I measuring disk lead resistance, has got rid of disturbing factor and has made the apparatus measures data obtain good repeatability.Because the range conversion is that one digit number is taken advantage of 10 integral number power with resistance, available standards 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 198 Ω between two brushes of first step disc, and the right resistance equals 1980 Ω, and total resistance is 180 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 the 3rd dish threw at the 10th, the 4th dish equated that with the 3rd dish partly resistance in parallel when the 4th dish was thrown different indicating value, the circuit resistance was constant.When the 3rd dish is not thrown at the 10th, the 4th dish is thrown different indicating values, the circuit resistance is not having IV " resistance changes during bracket panel; the 4th dish every increase stepping, circuit resistance can reduce half resistance of each stepping resistance, for the total resistance of holding circuit constant; at IV " in the bracket panel each stepping increase same resistance, resistance minimum when the 3rd step disc throws at the 10th, " bracket panel resistance all seals in circuit, makes the circuit resistance constant at this moment to allow IV.Because second dish and first 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 * 0.1 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 1 range, 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.
Basic range potential difference meter standard operation electric 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, the right electric current flows through III " is divided into two equal branch roads; when the 3rd dish throws at the 10th; two branch roads that flow through III measuring disk and IV measuring disk separate; when the III measuring disk does not throw at the 10th; flow through III measuring disk branch current and all flow through IV measuring disk resistance; 10 resistance of IV measuring disk play the effect of the 10th resistance of III measuring disk, when the IV measuring disk is thrown n behind the bracket panel brush
4The time, n
4Though~10 ohmically electric currents are exactly the right electric current, can regard two branch currents as and be formed by stacking, can be with separate computations when therefore calculating;
The standard operation electric 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 815 Ω with the resistance of setting up resistance R N, and 0~1 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:
U
X=12.5/11×0.88n
2+12.5/11×(16+0.88+0.088)+12.5/11×8n
1-1.25/11×(20-n
1)
×8-1.25/22×(10-n
4)×0.176-1.25/22×(10-n
3)×1.76
=n
2+200/11+1+0.1+100n
1/11-200/11+10n
1/11-0.1+0.01n
4-1+0.1n
3(mv)
=10n
1+n
2+0.1n
3+0.01n
4(mv)
More than be * during 1 range, the four measurement disks indicating value, 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).
The potential difference meter operating voltage is 1.5V, 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 1.4V~1.65V, gets fixed resistance R
0=124 Ω, adjustable resistance RP
1=20 * 10 Ω, RP
2Be 0~11 Ω.
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
1With R
2Equate, get 1M Ω here, resistance R
3Get 200 Ω, amplified signal shows that with reometer G resistance R is used for standard loop current limliting, resistance R
4Both end voltage is made amplifier signal voltage.
Claims (1)
1. two-measuring range DC potential difference meter, it has the adjustable resistance RP that regulates the working current size
1And RP
2, be used to reduce the fixed resistance R of supply voltage
0, the 815 Ω setting resistance R N of sampling usefulness and range of adjustment are at the adjustable resistance RP of 0~1 Ω during to standard
3, the resistor network that reaches on four step discs is connected in the potential difference meter work loop, and when the voltage drop on the setting resistance R N equated with the potential difference meter internal attachment standard, its working current equaled 1.25mA; Signal amplifies employing two OPA128, resistances and all equals 1M Ω resistance R
1With resistance R
2, 200 Ω resistance R
3The amplifying circuit of forming the differential output of differential input, input end is with the diode D of positive and negative connection
1And D
2Protect, amplified signal shows by reometer G, resistance R
4Both end voltage is made amplifier signal voltage; This two-measuring range DC potential difference meter is characterised in that first step disc is made up of I measuring disk that 20 * 8 Ω are respectively arranged and the I ' replacement dish, second step disc is made up of II measuring disk that 10 * 0.88 Ω are respectively arranged and the II ' replacement dish, the 3rd step disc is by " 9 ", non-resistance between " 10 " two contacts, these two contacts disconnect, all the other contacts are by the III measuring disk of 9 * 1.76 Ω resistance of resistance connection, 10 * 1.76 Ω the III ' replacement dishes are arranged and be not welded with resistance, the 10th independence, the III that all the other contacts connect " bracket panel forms; the 4th step disc is by being all IV measuring disk and the IV ' replacement dish that 10 * 0.176 Ω resistance form and the IV that 10 * 0.088 Ω resistance are arranged " bracket panel forms, except that first step disc, the brush of the measuring disk on all the other step discs oneself dish is connected with the brush of replacement dish; The I ' replacement is coiled and was connected the II ' replacement by 12.232 Ω resistance at the 20th o'clock and coil the 10th point, after connecting one 16.968 Ω resistance, the 0th of II measuring disk be connected with the 0th of I measuring disk, the I ' replacement is coiled at the 0th and is connected IV after connecting one 1810.32 Ω resistance " bracket panel the 0th point; IV " the 10th of bracket panel and III " the 10th of bracket panel be connected; IV " the bracket panel brush connects III " bracket panel all contacts except that the 10th contact; and III " bracket panel brush one tunnel connects the III ' replacement and coils the 0th point, another road is coiled at the 0th with the IV ' replacement after by 15.84 Ω resistance and is connected, and the 10th of III measuring disk directly is connected with the 20th of I measuring disk; The 9th of III measuring disk connects IV measuring disk the 0th point, and the 10th of IV measuring disk is connected with the 20th of I measuring disk; The I ' replacement dish brush and 20 Ω resistance r
1Be connected in parallel on potential difference meter measure portion positive pole, the other end of resistance r1 connects dpdt double-pole double-throw (DPDT) range selector K
1Layer * 0.1 range contact, a left side, right layer * 0.1 range contact and I measuring disk brush all with double-point double-throw switch K
1Left side layer * 1 range contact connection, 162 Ω resistance r
2One end connects K
1Right layer * 0.1 range contact, the other end connects K
1Right layer * 1 range contact, K
1Right layer * 1 range contact is connected on potential difference meter measure portion negative pole, double-point double-throw switch K
1Left side layer and right layer normally closed contact short circuit, potential difference meter is used to connect measured U
XTwo terminals, anodal terminal is connected with the 10th of II measuring disk, and the negative pole terminal is by galvanometer change-over switch K
2Be connected with the 0th of III measuring disk.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
CNB2005100623751A CN100386634C (en) | 2005-12-30 | 2005-12-30 | Two-measuring range DC potential difference meter |
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Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
CNB2005100623751A CN100386634C (en) | 2005-12-30 | 2005-12-30 | Two-measuring range DC potential difference meter |
Publications (2)
Publication Number | Publication Date |
---|---|
CN1818680A CN1818680A (en) | 2006-08-16 |
CN100386634C true CN100386634C (en) | 2008-05-07 |
Family
ID=36918774
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
CNB2005100623751A Expired - Fee Related CN100386634C (en) | 2005-12-30 | 2005-12-30 | Two-measuring range DC potential difference meter |
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Country | Link |
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CN (1) | CN100386634C (en) |
Citations (4)
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 |
CN1673753A (en) * | 2005-04-22 | 2005-09-28 | 骆乃光 | Portable potential difference meter with high resolution ratio |
CN1673754A (en) * | 2005-04-22 | 2005-09-28 | 骆乃光 | Portable potential difference meter |
CN1673755A (en) * | 2005-04-22 | 2005-09-28 | 骆乃光 | Potential difference meter with seven bit reading |
-
2005
- 2005-12-30 CN CNB2005100623751A patent/CN100386634C/en not_active Expired - Fee Related
Patent Citations (4)
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 |
CN1673753A (en) * | 2005-04-22 | 2005-09-28 | 骆乃光 | Portable potential difference meter with high resolution ratio |
CN1673754A (en) * | 2005-04-22 | 2005-09-28 | 骆乃光 | Portable potential difference meter |
CN1673755A (en) * | 2005-04-22 | 2005-09-28 | 骆乃光 | Potential difference meter with seven bit reading |
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CN1818680A (en) | 2006-08-16 |
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SE01 | Entry into force of request for substantive examination | ||
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Granted publication date: 20080507 Termination date: 20100201 |