CN100567996C - Two-range potentiometer - Google Patents

Abstract

A kind of two-range potentiometer that is used for dc voltage measurement, its first step disc is made up of a measuring disk and two bracket panels that are not welded with resistance, second step disc constitutes measuring disk by the ring resistance net, constitute bracket panel by 10 0.5 Ω resistance, each is made up of the 3rd step disc measuring disk and the replacement dish of 10 * 1 Ω, corresponding contact in each contact of the 4th step disc and the 3rd step disc on the measuring disk connects, the brush series connection 100k Ω resistance of the 4th step disc, the replacement dish of the 3rd step disc 9995 Ω resistance of connecting, and 529.392 Ω resistance are connected in parallel in the circuit together, and be connected in parallel on 800 Ω and two resistance of 7200 Ω and resistance measurement network and carry out the range conversion in the circuit, minimum resolution reaches 1 μ V, connect with lead between the measuring disk, do not switch, can ignore variation and thermoelectric potential influence when potential difference meter is measured by switch.

Description

Two-range potentiometer

Technical field

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

Background technology

Current for the potential difference meter that four measurement disks is arranged, in the connection between the four measurement disks, telophragma generally adopts switch to switch, and so just produces the variation of contact resistance, brings restriction to resolution.In order to overcome this problem, generally adopt big brush with the increase contact area, and adopt a silver-colored carbon/carbon-copper composite material; Application number 2005100622602 discloses the new method that the potential difference meter that four measurement disks is arranged solves the switch contact resistance variation, its first, each is made up of second step disc measuring disk and replacement dish, measuring disk is identical with resistance on the replacement dish, resistance of the every increase of measuring disk, the replacement dish just reduces same resistance, its the 3rd, the 4th step disc respectively has measuring disk, replacement dish and bracket panel are formed, because the 3rd step disc was declined at 10 o'clock, the total resistance of circuit changed when the 4th step disc was put different indicating value, the 3rd step disc was put at 10 o'clock, the total resistance of circuit was constant when the 4th step disc was put different indicating value, the 3rd step disc removes for this reason measuring disk, outside the replacement dish, increased bracket panel distinguish step disc put 10 and the circuit of declining 10 two kinds of situations connect, the 4th step disc has also increased bracket panel, has 10 resistance to insert or cut out several resistance respectively above and makes the total resistance of circuit constant.Four measurement disks is connected two and measures between terminal, and the brush on the step disc switch is got rid of outside the measurement loop, does not exist switch to switch between the resistance on the four measurement disks, does not also just produce variation; Because 15 ° of angles are rotated in each stepping of potential difference meter step disc switch, every layer of 24 contact that can distribute, the measuring disk of first step disc and replacement dish are 21 contacts, two-layer inside and outside needing, every layer all has resistance, and internal layer resistance is overproof makes troubles to maintenance, the measuring disk of the 4th step disc, replacement dish and each half storey of bracket panel, the step disc switch also needs inside and outside two-layer, and internal layer also has resistance, and maintenance is also inconvenient.

Summary of the invention

The objective of the invention is to design a kind of two-range potentiometer, in the connection of four measurement disks, do not switch by switch, first step disc cancellation replacement dish, and make four resistance on the step disc can both be contained in the switch skin, the switch internal layer is not welded with resistance.

Technical scheme of the present invention is taked like this: from the positive pole of potential difference meter 3V working power through the resistance measurement network formed by resistance on four step discs and range transfer resistance setting resistance R to 463 Ω _NAnd the lockable adjustable resistance R of 0～1 Ω _P3, again to 60 Ω resistance R ₀, through the adjustable resistance R of 10 23 Ω resistance compositions _P1And 0～25 Ω adjustable resistance R _P2Get back to the negative pole of working power and form potential difference meter work loop; Standard cell E _NAnodal through being connected to the double-point double-throw switch K of galvanometer G between two normally closed contacts ₂To setting up resistance R _NAnd lockable adjustable resistance R _P3, process 75K Ω current-limiting resistance R is to standard cell R again _NNegative pole is formed the potential difference meter standard loop; Be used to connect measured " U _X" two terminals, anodal terminal through the four measurement disks resistor network after, again through being connected to the double-point double-throw switch K of galvanometer G between two normally closed contacts ₂Form the potential difference meter equalizing network to the negative pole terminal; It is characterized in that first step disc has measuring disk I, it has 0,1,2 ... 22 totally 23 gears, except that between 0,1 contact, directly connecting, connect one of 10 Ω resistance between all the other each grade contacts, other has bracket panel I ' and bracket panel I ", the brush of bracket panel I ' and bracket panel I " brush be connected with lead, tie point is circuit node B, 0 contact of bracket panel I ' and bracket panel I " 0 contact isolated, all the other all contacts connect with lead; Second step disc is made up of measuring disk II and bracket panel II ', measuring disk II has 0,1,2 ... 10 totally 11 gears have the resistance R of 11 11 Ω above ₁～resistance R ₁₁, the 1st resistance R ₁One end welds the 2nd resistance R ₂One end, resistance R ₂The other end welds the 3rd resistance R ₃One end ... welding successively, the 10th resistance R ₁₀The other end and the 11st resistance R ₁₁An end tie point be circuit node C, the 11st resistance R ₁₁The other end and the 1st resistance R ₁The other end be connected in 0 point of measuring disk in the 3rd step disc, 0 of measuring disk is circuit node D in the 3rd step disc, measuring disk II goes up resistance R ₁With resistance R ₂Tie point be connected resistance R through 20 Ω resistance with the 1st grade of contact ₂With resistance R ₃Tie point be connected resistance R through 12 Ω resistance with the 2nd grade of contact ₃With resistance R ₄Tie point be connected resistance R through 6 Ω resistance with the 3rd grade of contact ₄With resistance R ₅Tie point be connected resistance R through 2 Ω resistance with the 4th grade of contact ₅With resistance R ₆Tie point be connected resistance R with the 5th grade of contact ₆With resistance R ₇Tie point be connected resistance R with the 6th grade of contact ₇With resistance R ₈Tie point be connected resistance R through 2 Ω resistance with the 7th grade of contact ₈With resistance R ₉Tie point be connected resistance R through 6 Ω resistance with the 8th grade of contact ₉With resistance R ₁₀Tie point be connected resistance R through 12 Ω resistance with the 9th grade of contact ₁₀With resistance R ₁₁Tie point be connected resistance R through 20 Ω resistance with the 10th grade of contact ₁With resistance R ₁₁Connect node D o'clock being connected with 0 grade of contact through 30 Ω resistance, is 10 resistance that resistance is 0.5 Ω on the bracket panel II ' of second step disc; The 3rd step disc is formed by being both measuring disk III and the replacement dish III ' that 10 1 Ω resistance form, and the brush of measuring disk III is connected with lead with the brush of replacement dish III '; The 4th step disc has only measuring disk IV, and the corresponding contact on its each contact and the measuring disk III connects; Bracket panel II ' the 10th contact and 800 Ω resistance R ₁₈An end be parallel to node A, node A connects the positive pole of potential difference meter working power, 0 contact of bracket panel II ' connects bracket panel I " 0 contact, the brush of bracket panel II ' connects bracket panel I " other contact except that 0 contact, the brush of measuring disk II is through 190 Ω resistance R ₁₂The back connects the brush and bracket panel I of bracket panel I ' " the Node B that is connected of brush; other contacts connection measuring disk I 22nd contact of bracket panel I ' except that 0 contact; measuring disk I the 0th, 1 contact is connected with node C; 0 contact of bracket panel I ' is connected with node D after through 220 Ω resistance, the brush of the measuring disk IV 100k Ω resistance R of connecting ₁₅Back and 184.725 Ω resistance R ₁₆The tie point of one end is circuit node E, the 10th contact of replacement dish III ' the 9995 Ω resistance R of connecting ₁₄Back connected node E, 529.392 Ω resistance R ₁₃One end connected node D, other end connected node E, 184.725 Ω resistance R ₁₆The other end and 7200 Ω resistance R ₁₇An end be connected in range selector K ₁* 1 range contact, 7200 Ω resistance R ₁₇The other end and 800 Ω resistance R ₁₈The other end be connected in range selector K ₁* 0.1 range contact, range selector K ₁Normally closed contact connect to set up resistance R _NNoble potential one end; Potential difference meter is used to connect measured " U _X" two measure terminal, anodal terminal is connected with measuring disk I brush, the negative pole terminal passes through double-point double-throw switch K ₂The back is connected with the 10th contact of measuring disk III.

By above technical scheme, first step disc need not the replacement dish, does not all have resistance on the two-layer bracket panel, can be contained in the switch nexine, and measuring disk I is contained in the switch skin; Second step disc need not the replacement dish, 15 ° of angles are rotated in each stepping of switch, each 11 contact of the bracket panel II ' of second step disc and measuring disk II are distributed in same one deck of switch, resistance is contained in the switch skin, three, the 4th step disc does not all have bracket panel, resistance can be contained in the switch skin, unloads when resistance is overproof and loads onto easily, and this brings convenience for debugging and maintenance; This makes potential difference meter simple in structure, and volume-diminished has also reduced production cost; On the total circuit partly in potential difference meter internal compensation loop and work loop, there is not switch, so there is not variation influence, when the reset of potential difference meter four measurement disks, the zero potential of potential difference meter is the zero potential that D is ordered, in equalizing network, do not exist working current to flow through lead resistance, so this potential difference meter zero potential is very little, owing on the total circuit partly in potential difference meter internal compensation loop and work loop, do not have switch to switch, so this potential difference meter thermoelectrical potential and variable thermoelectrical potential are also very little.

Description of drawings

Fig. 1 is a principle of the invention circuit.

Embodiment

In Fig. 1, measuring disk II is 11 the 11 end to end resistance rings of Ω between node C and node D, when measuring disk II puts " 5 " or puts " 6 ", the brush of measuring disk II is to being that 5 11 Ω resistance are in parallel with 6 11 Ω resistance between the node D, back in parallel resistance is 30 Ω to the maximum, other contact of measuring disk II all will be connected to 30 Ω to the resistance between the node D, and corresponding point directly are connected on the 5th, 6 contacts and the resistance ring; When measuring disk II put " 4 " or puts " 7 ", the brush of measuring disk II was to being that 4 11 Ω resistance are in parallel with 7 11 Ω resistance between the node D, and back in parallel resistance is 28 Ω, so 4,7 contacts are connected with corresponding point on the resistance ring through 2 Ω resistance; When measuring disk II put " 3 " or puts " 8 ", the brush of measuring disk II was to being that 3 11 Ω resistance are in parallel with 8 11 Ω resistance between the node D, and back in parallel resistance is 24 Ω, so 3,8 contacts are connected with corresponding point on the resistance ring through 6 Ω resistance; When measuring disk II put " 2 " or puts " 9 ", the brush of measuring disk II was to being that 2 11 Ω resistance are in parallel with 9 11 Ω resistance between the node D, and back in parallel resistance is 18 Ω, so 2,9 contacts are connected with corresponding point on the resistance ring through 12 Ω resistance; When measuring disk II set or when putting " 10 ", the brush of measuring disk II is to being that 1 11 Ω resistance is in parallel with 10 11 Ω resistance between the node D, and back in parallel resistance is 10 Ω, so 1,10 contacts are connected with corresponding point on the resistance ring through 20 Ω resistance; When measuring disk II reset, the brush of measuring disk II is between the node D being the connections of 30 Ω resistance.

The first step disc reset, second step disc are put " n " (n=0,1,2,3 ... 10) time, Node B is that two resistance that are both 220 Ω are in parallel with resistance value between the node D, is 110 Ω therefore.

First step disc is put " n " (n=0,1,2,3 ... 22), during the second step disc reset, Node B and resistance value between the node D also are that the resistance of two 220 Ω is in parallel, so resistance also is 110 Ω.

When first, second step disc during not reset, except that second step disc was put " 10 ", the calculating of the resistance value between Node B and the node D need be carried out triangle-star conversion.

During the second step disc set, the calculating of resistance value between Node B and the node D: establish resistance (R ₂+ R ₃+ ... + R ₉+ R ₁₀) and resistance R ₁₁The both sides resistance is equivalent to resistance r ₁, resistance R ₁₁With resistance R ₁The both sides resistance is equivalent to resistance r ₁' resistance (R ₂+ R ₃+ ... + R ₉+ R ₁₀) and resistance R ₁The both sides resistance is equivalent to resistance r ₁", be equivalent to resistance r ₁, r ₁', r ₁" intersection point is Q ₁:

R then ₁=(R ₂+ R ₃+ ... + R ₉+ R ₁₀) * R ₁₁/ (R ₁+ R ₂+ ... + R ₁₀+ R ₁₁)=9 * 11 * 11/11 * 11 Ω=9 Ω

r ₁’＝R ₁×R ₁₁/(R ₁+R ₂+…+R ₁₀+R ₁₁)＝11×11/11×11Ω＝1Ω

r ₁”＝(R ₂+R ₃+…+R ₉+R ₁₀)×R ₁/(R ₁+R ₂+…+R ₁₀+R ₁₁)＝9×11×11/11×11Ω＝9Ω

Resistance value equals (210 Ω+r between Node B and the node D ₁) * (190 Ω+20 Ω+r ₁")/2 * 219 Ω+r ₁'=219 Ω/2+1 Ω=109.5 Ω+1 Ω=110.5 Ω

Claims (1)

1, a kind of two-range potentiometer, from the positive pole of potential difference meter 3V working power through the resistance measurement network formed by resistance on four step discs and range transfer resistance setting resistance R to 463 Ω _NAnd the lockable adjustable resistance R of 0～1 Ω _P3, again to 60 Ω resistance R ₀, through the adjustable resistance R of 10 23 Ω resistance compositions _P1And 0～25 Ω adjustable resistance R _P2Get back to the negative pole of working power and form potential difference meter work loop; Standard cell E _NAnodal through being connected to the double-point double-throw switch K of galvanometer G between two normally closed contacts ₂To setting up resistance R _NAnd lockable adjustable resistance R _P3, process 75K Ω current-limiting resistance R is to standard cell E again _NNegative pole is formed the potential difference meter standard loop; Be used to connect measured " U _X" two terminals, anodal terminal through the four measurement disks resistor network after, again through being connected to the double-point double-throw switch K of galvanometer G between two normally closed contacts ₂Form the potential difference meter equalizing network to the negative pole terminal; It is characterized in that first step disc has measuring disk I, it has 0,1,2 ... 22 totally 23 gears, except that between 0,1 contact, directly connecting, connect one of 10 Ω resistance between all the other each grade contacts, other has bracket panel I ' and bracket panel I ", the brush of bracket panel I ' and bracket panel I " brush be connected with lead, tie point is circuit node B, 0 contact of bracket panel I ' and bracket panel I " 0 contact isolated, all the other all contacts connect with lead; Second step disc is made up of measuring disk II and bracket panel II ', measuring disk II has 0,1,2 ... 10 totally 11 gears have the resistance R of 11 11 Ω above ₁～resistance R ₁₁, the 1st resistance R ₁One end welds the 2nd resistance R ₂One end, resistance R ₂The other end welds the 3rd resistance R ₃One end ... welding successively, the 10th resistance R ₁₀The other end and the 11st resistance R ₁₁An end tie point be circuit node C, the 11st resistance R ₁₁The other end and the 1st resistance R ₁The other end be connected in 0 point of measuring disk in the 3rd step disc, 0 of measuring disk is circuit node D in the 3rd step disc, measuring disk II goes up resistance R ₁With resistance R ₂Tie point be connected resistance R through 20 Ω resistance with the 1st grade of contact ₂With resistance R ₃Tie point be connected resistance R through 12 Ω resistance with the 2nd grade of contact ₃With resistance R ₄Tie point be connected resistance R through 6 Ω resistance with the 3rd grade of contact ₄With resistance R ₅Tie point be connected resistance R through 2 Ω resistance with the 4th grade of contact ₅With resistance R ₆Tie point be connected resistance R with the 5th grade of contact ₆With resistance R ₇Tie point be connected resistance R with the 6th grade of contact ₇With resistance R ₈Tie point be connected resistance R through 2 Ω resistance with the 7th grade of contact ₈With resistance R ₉Tie point be connected resistance R through 6 Ω resistance with the 8th grade of contact ₉With resistance R ₁₀Tie point be connected resistance R through 12 Ω resistance with the 9th grade of contact ₁₀With resistance R ₁₁Tie point be connected resistance R through 20 Ω resistance with the 10th grade of contact ₁With resistance R ₁₁Connect node D o'clock being connected with 0 grade of contact through 30 Ω resistance, is 10 resistance that resistance is 0.5 Ω on the bracket panel II ' of second step disc; The 3rd step disc is formed by being both measuring disk III and the replacement dish III ' that 10 1 Ω resistance form, and the brush of measuring disk III is connected with lead with the brush of replacement dish III '; The 4th step disc has only measuring disk IV, and the corresponding contact on its each contact and the measuring disk III connects; Bracket panel II ' the 10th contact and 800 Ω resistance R ₁₈An end be parallel to node A, node A connects the positive pole of potential difference meter working power, 0 contact of bracket panel II ' connects bracket panel I " 0 contact, the brush of bracket panel II ' connects bracket panel I " other contact except that 0 contact, the brush of measuring disk II is through 190 Ω resistance R ₁₂The back connects the brush and bracket panel I of bracket panel I ' " the Node B that is connected of brush; other contacts connection measuring disk I 22nd contact of bracket panel I ' except that 0 contact; measuring disk I the 0th, 1 contact is connected with node C; 0 contact of bracket panel I ' is connected with node D after through 220 Ω resistance, the brush of the measuring disk IV 100k Ω resistance R of connecting ₁₅Back and 184.725 Ω resistance R ₁₆The tie point of one end is circuit node E, the 10th contact of replacement dish III ' the 9995 Ω resistance R of connecting ₁₄Back connected node E, 529.392 Ω resistance R ₁₃One end connected node D, other end connected node E, 184.725 Ω resistance R ₁₆The other end and 7200 Ω resistance R ₁₇An end be connected in range selector K ₁* 1 range contact, 7200 Ω resistance R ₁₇The other end and 800 Ω resistance R ₁₈The other end be connected in range selector K ₁* 0.1 range contact, range selector K ₁Normally closed contact connect to set up resistance R _NNoble potential one end; Potential difference meter is used to connect measured " U _X" two measure terminal, anodal terminal is connected with measuring disk I brush, the negative pole terminal passes through double-point double-throw switch K ₂The back is connected with the 10th contact of measuring disk III.

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