CN106226575A - A kind of DC potentiometer - Google Patents

Abstract

A kind of DC potentiometer for DC voltage measurement, its four step discs are all made up of with replacement dish measurement dish, measurement dish is all 10 Ω resistances with the resistance on replacement dish, and the structure of four step discs is identical, instrument manufacturing is brought convenience by this, and during use, switch contact resistance is deteriorated and thermoelectrical potential does not affect this DC potentiometer measurement result, and it has two amount limits, the measurement upper limit is 1V, and minimum step is 10 μ V.

Description

A kind of DC potentiometer

Technical field

The present invention relates to the instrument that DC voltage is measured.

Background technology

The impact of DC potentiometer variation and thermoelectrical potential in order to solve contact resistance, the big brush of general employing is to increase Contact area, and use silver-copper composite, which increases switch and also increase instrument volume, add instrument cost, adopt The resistance being only used for each stepping by the method for electric current superposition uses small resistor, typically all 0.01 Ω, if each step The resistance one entering resistance is big, and the ratio of electric current will be overproof, and owing to the resistance of step disc resistance is little, the voltage that it can be measured is relative Also ratio is relatively low.

Summary of the invention

It is an object of the invention to be designed with a kind of DC potentiometer of four step discs, it overcomes the variation of contact resistance And the impact of thermoelectrical potential, it is not required that big switch, this can reduce cost, reduce instrument volume, and can measure 1V.

Technical scheme is so taked: it is connected into the included working power of 4.5V with three groups of No. 1 aneroid battery, and it has Range of accommodation adjustable resistance R between 7～75 Ω_P1, range of accommodation lockable adjustable resistance R between 0～1.09 Ω_P2、 Range of accommodation adjustable resistance R between 0～680 Ω_P3, have two double-point double-throw switch, have four step discs, each step disc On by having 0,1, the measurement dish of 2 ... 10 totally 11 gears with have 0,1, the replacement dish composition of 2 ... 10 totally 11 gears, survey Amount dish with weld 10 Ω resistance one on replacement dish between each two adjacent gear positions contact, measurement dish and replacement dish when rotating with Step, measurement dish often increases a resistance, and in circuit, replacement dish just reduces by a resistance, and the total resistance of holding circuit is constant；Its feature It is: on the first step disc, the metal contact ring of measurement dish I is connected with the metal contact ring wire of replacement dish I ', the second stepping On dish, the metal contact ring of measurement dish II and the metal contact ring of replacement dish II ' are by 2000 Ω resistance R₁Connect, the 3rd stepping On dish, the metal contact ring of measurement dish III is connected with the metal contact ring wire of replacement dish III ', and the 4th step disc is measured The metal contact ring of dish IV passes through 2000 Ω resistance R with the metal contact ring of replacement dish IV '₂Connect；Electric current is from included work electricity Source positive pole connects double-point double-throw switch K₁K_1-1Layer normally-closed contact, double-point double-throw switch K₁Throw × 1 amount in limited time, double-point double-throw switch K₁K_1-1Layer × 1 amount limit contact connects double-point double-throw switch K₁K_1-2Layer normally-closed contact, K_1-2Layer × 1 amount limit contact is passed through 102.01 Ω resistance R₅Connect node A, K_1-2Layer normally-closed contact is through 917 Ω resistance R₄, then through lockable adjustable resistance R_P2 Connect node A；Double-point double-throw switch K₁Throw × 0.1 amount in limited time, double-point double-throw switch K₁K_1-1Layer normally-closed contact and K_1-2Layer is normally closed Contact is each to be disconnected with × 1 amount limit contact, double-point double-throw switch K₁K_1-1Layer × 0.1 amount limit contact is through adjustable resistance R_P3And 2580 Ω resistance R₆Connect double-point double-throw switch K₁K_1-2Layer normally-closed contact；Electric current is divided into two-way after node A: upwards a road is even Connecing replacement dish II ' the 10th contact on the second step disc, replacement dish II ' the 0th contact connects replacement dish I ' the 10th on the first step disc Contact, on the first step disc, the 0th contact of measurement dish I connects measurement dish II the 10th contact on the second step disc, measurement dish II the 0th Through adjustable resistance R after contact connection node B_P1It is connected with included working power negative pole；Lead up to downwards 19000 Ω resistance R₇ Connecting the 0th contact of replacement dish IV ' on the 4th step disc, the 10th contact of replacement dish IV ' connects replacement dish on the 3rd step disc 0th contact of III ', on the 3rd step disc, the 10th contact of measurement dish III connects on the 4th step disc the 0th of measurement dish IV the and touches Point, the 10th contact of measurement dish IV is through 8900 Ω resistance R₃Connecting node B, DC potentiometer is measured for connecting “U_X" two terminals, positive pole terminal connects measurement dish I the 10th point, and negative pole terminal is connected to galvanometer between two normally-closed contacts The double-point double-throw switch K of G₂It is connected with measurement dish IV the 0th afterwards, DC potentiometer internal attachment standard battery E_NPositive pole connects double-pole Commutator K₁K_1-2Layer normally-closed contact, internal attachment standard battery E_NNegative pole is connected to galvanometer G's between two normally-closed contacts Double-point double-throw switch K₂Connect 100K Ω resistance R₈Afterwards with lockable adjustable resistance R_P2Sliding contact connect.

By above technical scheme, between four step disc contacts of DC potentiometer, resistance is identical, and structure is consistent；With “U_X" the four measurement disks that connect of two measurement terminals on resistance, when step disc switch, the resistance that welds together hinders Value is to produce change, and during step disc switching, switch contact resistance is deteriorated between 0.1～1m Ω, and it only affects electric current distribution Ratio, owing to it is connected in big resistance, as the first step disc switch contact resistance be deteriorated be connected in 200 Ω circuit, Therefore the impact on current distributing can be ignored, and during step disc switching, the thermoelectrical potential of switch is owing to occurring the most in pairs, greatly Little identical, in opposite direction, can offset, and the thermoelectrical potential of four each branch road of step disc several μ V is all direct or indirect and lithium electricity Pond both ends of power connects, and in the voltage drop in units of volt, the impact of current distributing can also be neglected by the thermoelectrical potential of several μ V Slightly, therefore, using technical scheme, during the switching of DC potentiometer step disc, switch contact resistance is deteriorated and thermoelectrical potential is to " U_X" Measure terminal for two not affect, and the resistance on the first step disc is 10 Ω, with application number 201420419568.2 and Shen Please number 201420419494.2 ratios much greater, therefore can be used to measure voltage the most much higher.

Accompanying drawing explanation

Fig. 1 is the schematic circuit of the present invention.

Detailed description of the invention

Embodiment 1, in FIG, 10 × 10 Ω on the first step disc measurement dish I and replacement dish I ', represent measurement dish I with Having 10 resistances on replacement dish I ' is the resistant series of 10 Ω, and on step disc, heavy black bar represents metal contact ring, hollow little Circle represents that hard contact, four-headed arrow represent metallic brush；Other three step discs are identical.

Between DC potentiometer node A and node B, the resistive arrangement of lower section becomes bigger than upper resistance per square 100 times, standard work Making electric current and be designed to 11.11mA in × 1 amount limit, therefore between node A and node B, the electric current of lower section is 0.11mA, node A and joint Between some B, the electric current of top is 11mA.

It is 2000 Ω resistance R between the second step disc two brush₁The second step disc and the first step disc is flowed through with electric current 200 Ω resistor coupled in parallel, therefore 10mA electric current flows through the first step disc, and 1mA flows through 2000 Ω resistance R₁, between node A and node B The resistance of top is 2000/11 Ω+100 Ω, and between node A and node B, the resistance of lower section is 100 × (2000/11 Ω+100 Ω), between the 4th step disc two brush, resistance is 2000/11 Ω, lower resistance per square R between node A and node B₃, resistance R₇Sum It is 100 × (2000/11 Ω+100 Ω)-(2000/11 Ω+100 Ω)=99 (2000/11 Ω+100 Ω)=27900 Ω.Wherein Resistance R₃It is necessary for 8900 Ω, then resistance R₇=27900 Ω-8900 Ω=19000 Ω.

Limit in × 1 amount, resistance R₄Serial adjustable resistance R_P2With resistance R₅Parallel connection, the resistance after parallel connection about 91.8 Ω, works as electricity Source internal resistance is disregarded, adjustable resistance R_P1Resistance is not-time, and circuit always hinders about 279 Ω, 11.11mA electric current to be obtained, and supply voltage needs 4.12V.Wanting DC potentiometer operating current stable, often group aneroid battery electromotive force is at more than 1.4V, new aneroid battery electromotive force At 1.65V, when after three groups of aneroid battery series connection of DC potentiometer, electromotive force change between 4.2～4.95V, by regulate 7～ 75 Ω adjustable resistance R_P1Make DC potentiometer operating current in standard state.

Limit in × 1 amount, 917 Ω resistance R₄Series connection 0～1.09 Ω adjustable resistance R_P2After be 102.01 Ω resistance R₅9 times, So flowing through resistance R₄, adjustable resistance R_P2Electric current is 1/10th of whole operating current, i.e. 1.111mA；Due to unsaturation mark The electromotive force of quasi-battery is discrete, between 1.0188V～1.0196V, and therefore 917 Ω resistance R₄Series connection 0～1.09 Ω can Adjust resistance R_P2, can be with the excursion of coverage criteria cell emf.

Limit in × 0.1 amount, double-point double-throw switch K₁K_1-1Layer normally-closed contact connects adjustable resistance R_P3Again through 2580 Ω electricity Resistance R₆Connect double-point double-throw switch K₁K_1-2Layer normally-closed contact, K_1-2Layer normally-closed contact and K_1-2Layer × 1 amount limit contact disconnects, at this moment Adjustable resistance R_P3Put minima circuit always to hinder and reach 3784 Ω, after three groups of aneroid battery series connection of DC potentiometer electromotive force 4.2～ Between 4.95V during change, by regulation 0～680 Ω adjustable resistance R_P3Make DC potentiometer operating current in standard state.

The standard operating current of DC potentiometer is obtained by: 0.1V standard signal voltage by polarity and unidirectional current Tentiometer " U_x" two measure terminal and connect, DC potentiometer double-point double-throw switch K₁Putting × 0.1 amount limit, each step disc always shows It is worth identical with standard signal magnitude of voltage, double-point double-throw switch K₂Throw to the left side, regulate adjustable resistance R_P1, make galvanometer G nulling；Again By double-point double-throw switch K₂Throw to the right, regulate adjustable resistance R_P2, make galvanometer G nulling, after repeating once, adjustable resistance R_P2Locking, the operating current that at this moment DC potentiometer limits in × 0.1 amount is with regard to standardization；Again 1V standard signal voltage by polarity With DC potentiometer " U_x" two measure terminal and connect, DC potentiometer double-point double-throw switch K₁Put × 1 amount limit, each stepping The total indicating value of dish is identical with standard signal magnitude of voltage, double-point double-throw switch K₂Throw to the left side, if the total indicating value of each step disc is to correct errors Difference, is reduced by 102.01 Ω resistance R₅Resistance value, if the total indicating value of each step disc is negative error, just increase 102.01 Ω resistance R₅Resistance value, when instrument uses, first proofread standard, when reading dial will be carried out reading, reading again after check and correction standard.

When, after operating current standardization, n put by I measurement dish₁, n put by ii measurement dish₂, n put by ii I measurement dish₃, iv is surveyed N put by amount dish₄, switch K throws the left side, at this moment connects measured " U_X" voltage is between two terminals:

U_X=10 × 10n₁+10×10×10+10n₂-0.11×8900-0.1×10×10-0.01×10(10-n₄)- 0.1×10(10-n₃)(mV)

U_X=100n₁+10n₂+10×10×10-979-10-1+0.1n₄-10+n₃(mV)

U_X=100n₁+10n₂+n₃+0.1n₄(mV)。

Claims (1)

1. a DC potentiometer, it is connected into the included working power of 4.5V with three groups of No. 1 aneroid battery, and it has range of accommodation to exist Adjustable resistance R between 7～75 Ω_P1, range of accommodation lockable adjustable resistance R between 0～1.09 Ω_P2, range of accommodation exists Adjustable resistance R between 0～680 Ω_P3, have two double-point double-throw switch, have four step discs, on each step disc by having 0,1, 2 ... 10 totally 11 gears measurement dish with have 0,1, the replacement dish composition of 2 ... 10 totally 11 gears, measurement dish and replacement Welding 10 Ω resistance one on dish between each two adjacent gear positions contact, measurement dish and replacement dish are Tong Bu when rotating, and measurement dish is every Increasing a resistance, in circuit, replacement dish just reduces by a resistance, and the total resistance of holding circuit is constant；It is characterized in that: the first step Enter the metal contact ring of measurement dish I on dish to be connected with the metal contact ring wire of replacement dish I ', measurement dish on the second step disc The metal contact ring of II passes through 2000 Ω resistance R with the metal contact ring of replacement dish II '₁Connect, measurement dish on the 3rd step disc The metal contact ring of III is connected with the metal contact ring wire of replacement dish III ', the metal of measurement dish IV on the 4th step disc Contact ring passes through 2000 Ω resistance R with the metal contact ring of replacement dish IV '₂Connect；Electric current connects from included working power positive pole Double-point double-throw switch K₁K_1-1Layer normally-closed contact, double-point double-throw switch K₁Throw × 1 amount in limited time, double-point double-throw switch K₁K_1-1Layer × 1 amount limit contact connects double-point double-throw switch K₁K_1-2Layer normally-closed contact, K_1-2Layer × 1 amount limit contact is through 102.01 Ω resistance R₅Connect node A, K_1-2Layer normally-closed contact is through 917 Ω resistance R₄, then through lockable adjustable resistance R_P2Connect node A；Double Double-pole double throw switch K₁Throw × 0.1 amount in limited time, double-point double-throw switch K₁K_1-1Layer normally-closed contact and K_1-2Layer normally-closed contact is each with × 1 Amount limit contact disconnects, double-point double-throw switch K₁K_1-1Layer × 0.1 amount limit contact is through adjustable resistance R_P3And 2580 Ω resistance R₆Even Meet double-point double-throw switch K₁K_1-2Layer normally-closed contact；Electric current is divided into two-way after node A: upwards a road connects the second step disc Upper replacement dish II ' the 10th contact, replacement dish II ' the 0th contact connects replacement dish I ' the 10th contact on the first step disc, the first stepping On dish, the 0th contact of measurement dish I connects measurement dish II the 10th contact on the second step disc, and measurement dish II the 0th contact connects node B After through adjustable resistance R_P1It is connected with included working power negative pole；Lead up to downwards 19000 Ω resistance R₇Connect the 4th stepping 0th contact of replacement dish IV ' on dish, on the 10th contact connection the 3rd step disc of replacement dish IV ', the 0th of replacement dish III ' the touches Point, on the 3rd step disc, the 10th contact of measurement dish III connects the 0th contact of measurement dish IV, measurement dish IV on the 4th step disc The 10th contact through 8900 Ω resistance R₃Connecting node B, DC potentiometer is for connecting measured " U_X" two terminals, Positive pole terminal connects measurement dish I the 10th point, and negative pole terminal is connected to the DPDT of galvanometer G between two normally-closed contacts and opens Close K₂It is connected with measurement dish IV the 0th afterwards, DC potentiometer internal attachment standard battery E_NPositive pole connects double-point double-throw switch K₁'s K_1-2Layer normally-closed contact, internal attachment standard battery E_NNegative pole is connected to the double-point double-throw switch of galvanometer G between two normally-closed contacts K₂Connect 100K Ω resistance R₈Afterwards with lockable adjustable resistance R_P2Sliding contact connect.