RU1826070C - Resistance and conductance box - Google Patents

Abstract

Usage: in electrical measuring and electromodulating technology, namely in multi-valued measures of electrical resistance. SUMMARY OF THE INVENTION: a resistance and conductivity magazine comprises a controllable scaled multi-resistor, a voltage follower, an inverter. M voltage to current converters, M switch groups (M 4), resistor divider. The introduction of five current clamps, five potential clamps and a bipolar switch in two directions increased the working range and accuracy of the magazine, C 6 ill., 2 tab.

Description

The invention relates to electrical measuring electro-modeling technique, namely to multi-valued electrical resistance measures (stores).

The purpose of the invention is to increase accuracy and increase the operating range.

The drawing shows a structural electrical diagram of a store of resistance and conductivity.

The resistance store comprises a controllable scaled multi-resistor 1 with a first pole a and a second pole b, a first voltage follower based on operational amplifier 2. inverter 3, M converters 4.1. 42 ..., 414. M voltage to current, M reference resistors 5.1.

5.25.i5.M, M groups of switches

6.1.6.26i, ... 6.M, containing A and (A + 1)

keys 7.1. 7.2, ... 7 A, ..; M.O., M.1

M A + 1, resistor divider 8. made on A identical resistors 9.1,

9.29.A with rated resistance

R Rg i Rg.2 ... Rg.A (the drawing shows a divider 8 for the number system with base A 10).

The inverter 3 is made on an operational amplifier 10 controlled by a multi-resistor 11 and an adjustable resistor 12.

The device is equipped with a first current clamp 13, a second current clamp f4, a third current clamp 15. a fourth current clamp 16 and a fifth current clamp 17.

The device has a first potential terminal 18. a second potential terminal 19, a third potential terminal 20, a fourth potential terminal 21 and a fifth potential terminal 22, switch 2P2N 23.

The scheme shown in the drawing can be divided into two subsystems

00

go about h

about

1) controlled scaled multistor 1 with adjustable P code resistance levels:

Rp 10P Ohm,

0)

where P is an integer (or zero) from the next row,

P -3; -2; -1; 0; 1: 2: 3; ... 12; (2) 2) code-controlled converter 24 voltage U to voltage p

--K () - Xi ... Xi ... Xm) and

 -K 0, XiXi, ..., XwU, (3)

where U is the input voltage of the converter 3; K is the conversion coefficient of the Converter 3, set from a number

K-th + 2; -14)

XiXi, ..., Hm - switch readings

6.16.I, ..., 6.M, adequate to the number of included stages of the divider 8;

XiX | Xm - readings of switches 6.16.16.M, adequate to the number

off stages of the divider 8 of the current cases.

Further in the table. Figure 1 shows the three main layouts (1a, 2a and 3a) of a large-scale multi-resistor 1 into a 24 voltage U to voltage converter (p (3), as well as equivalent circuits (16, 26 and 36) of these three units (1a-2a) -3a).

The authors of prototype 1 and the examination did not take into account that: “the input impedance of the inverting amplifier circuit is significantly smaller than the intrinsic input impedance of the operational amplifier 36 s. 77.

In instrumentation and computer engineering, operational amplifiers with an output voltage tp ± 10 V and an output current I ± 10 mA have found the greatest application. With these output signals, the resistance R23 of the resistor 23 take no more

V23m3ks - - QJ 1 ° a01 - U4 Ohm, (5)

where, in order to obtain conversion rates, you must have the resistance:

K -1 (f2 K -10 K -1 K K

k - uR22 -102 Ohm

R22 - U3 Ohm

R22 1040m

Н22 Ю5Ом (6)

Y22 1060m

R22-1070m

R22 - 1080m.

Having made a mistake (simplification of the task) in neglecting (in the prototype) the effect of directly shunting the resistance R of the multistor 1 by the resistance R22 of the input of the inverter 3, the author and expert 1 ignored the fact that instead of one resistance R in creating the signal, Dab 1 actually takes a parallel connection resistances Rp and R23.

The error simplification of the task in the prototype 5y3 is determined by the formula

5

0

5

(5y:

Rp + R23 .100%, (7)

whence it follows that in the prototype for different values of the resistance Rp, namely

4

Rp R23 UCHOhm Rp 103Ohm Rp 1020m Rp 10 6m R 1 Ohm R-0.1 Ohm

5use 50% (8) (9) (S) (, 1% (11), 01% (12), 001% (13)

those. only in (12) the indicated error can be neglected if the accuracy class of the prototype is not better than 0.05%.

Claimed resistance store

compares favorably with the prototype in that the value of its operating current (Fig. 2) with four-clamp connection (2, a; 2, c) is not limited to the maximum permissible output current of the first repeater-amplifier 2 Ioy2 10 mA). If in the prototype (2A, Fig. 2 and 1, table. 1) operating current

I 1ou2 10 mA,

(14)

then with the resistance of the included steps of the multistor 1

potential difference Rp-1 Ohm Ohm-, 01 V

vi

, -2

v2

  Ohm, 001 V Ohm LNUab 10 2 Ohm A 0.0001 V Ohm, 00001 V,

and so on, whereas in the claimed device, when sharing currents 15 and 16, the operating current of the magazine is determined by the value of the maximum allowable current for the corresponding resistance level of multistor 1 (2, c, figs. 2 and 3) of the table. 1), namely:

Rp 0.1 Ohm (A)

potential difference Ohm 1A 1V

Rp Ohm () LHUab Ohm, SR Rp Ohm (A) 2 Ohm-10A 0.1V Rp 10 3Oi4l 30A)

which, respectively, 100, 300, 1000 and 3000 times more than that of the prototype. This allows you to expand the range of the store in the direction of low resistances (at R 1; 0.1: 0.01; 0.001 Ohms or less).

As in the prototype (2a.b. Fig. 2 and 1) table. 1) inverter 3 its input signal

Uab.IRp U

(fifteen)

Ui li (A- 1 -Xi) R Uid Ui h (A - 1 - Xi) R - Utd

UM IM (A - XM) Did

R5 R

R5.I R

RS.M

the amount of which

10

 + ... + Ui + ... + UM under the following conditions:

(nineteen)

R- / R1-A 1- R / Rl R / RM 10

M

(twenty)

converts to its output

Uid KIRp KU. (16)

Further, the voltage-signal Uld is output from the inverter to the inverting inputs of the converters 4.1. 4.24.M voltage in currents

li Uid / R5.i KIRp / R5.i

li - Uid / R5.i - KIRp / Rg.i

lM Uid / R5.M KIRp / R5.M, (17) where Rs.1 is the resistance of the resistor 5.1,

RS.I resistor 5.I,

RS.M resistor 5.M

Current and hIjIM flow from the outputs of the corresponding amplifiers OU 4.1,

..., 4i 4.M via closed contacts

switches 6.1 6.16.M. the included resistors-stages of the divider 8, - reference resistors 5.15.i5.M. Each of these loop currents is defined by a corresponding resistance RI,

..., RiRM resistors 5.15.1, .... 5.M in

1-mm-mm circuit circuits of the device.

Each of the dIM currents. pass

through the corresponding included number Xi Xi Xm resistor

stugtenier divider 8, creates at the last corresponding voltage drop:

where A 10 is the base of the adopted number system;

Xi is the number of excluded resistance stages R of the divider 8 from the current loop h by decade switches 6.1;

Xi is the number of excluded resistance stages R of the divider 8 from the current loop fi by the decade switch 6.I:

Xm is the number of excluded resistance stages R of the divider 8 from the current loop by the 1st decade switch 6.M, as the total voltage drop (U) on the divider 8 is determined by the formula

(1-0, Xi, ..., XiXm),

(21)

35

which, taking into account (12), can be represented as follows

(1-0, XiXi, ..., Xm).

(22)

At K 0, the voltage U with a polarity opposite to that of the voltage ua is applied between the output and the inverting input of the amplifier-amplifier 2 and is repeated by the latter between the pole f and b as the voltage Kr u Uj, (23) also opposite in polarity voltage drop at the switched-on stage resistance Rp of the scaled multistor 1.

The total voltage on the path of the working current I between the poles a and f is: Uaf Uab + Ubf Uab + DЈ

- IRp + (1 - O.X1. .... XiXM)

-Shr (1 + K - K O.XiXiXm), (24)

55 where in accordance with Ohm's law reproduced (simulated) between the poles a and f of the current I resistance

Raf - Uaf / l - Rp (K + 1 - K 0, XiXiXm). (25)

A feature of the invented resistance magazine is that, at K -1, its resistance Raf, according to (25), can be determined using the extremely simple and convenient formula for use

Raf + Q, XlX | XM RP

+ 0, XiXiXm LawOm, (26)

where P can be any integer (or zero) ranging from -3 to 0.

At K -1, the inventive device can be used, like the prototype, to reproduce negative resistances.

Compared with the prototype, the claimed device (option 2B, Fig. 2) has the following advantages:

1) can reproduce any resistance from the following array:

those. from minimum resistance at

M 5:

, s.

,-8

Raf (-3) 0.00001 S ohm (28) to maximum resistance

Raf (1) 0.999 1 Ohm 1 Ohm, (29)

whereas, according to the evidence presented above, the prototype can only have a scale

Rp 0, XiXiXm 10m,

(thirty)

with accuracy classes not better than 0.05-0.1 (%) due to an error in simplifying the problem of 0.01% for case (30);

2) can have working currents much more than that of the prototype;

3) can be used as a low-resistance measure with four- and three-clamp connections to an external circuit according to 3-4 (tab. 2, while the prototype is intended only for two-clamp connection (1), tab. 1).

An additional advantage of the claimed device is that it can be used as a wide-range multi-valued measure of the electrical conductivity of small values (electrical resistance of large values).

The aforementioned new application of the claimed device is realized with the table. 1 by connecting 3 a controlled scale multistor 1 and a voltage converter 23 to voltage p. In this case, this embodiment of the device under consideration is connected to an external ohmmeter according to the circuit according to FIG. 3, and to a more accurate quasi-bridge according to FIG. 4.

The operation of the three-clamp device according to FIG. 2 in the diagrams of FIG. 3 and 4 are better

only consider after replacing the ATaTcTd block diagram in the indicated circuits with an equivalent conductivity triangle, namely:

fifteen

ATaTcTd AGcdGacGad,

(31)

where Gcd is the input conductivity of DTaTsTa;

Gac - pass through conductivity ATaTcTd;

Gad is the output conductivity of DTaTsTa; those. after obtaining the circuits of FIG. 5 and 6, from which the following can be seen:

1) GacJ conductivity is measured

2) the input conductivity Gcd is only a load for power supplies 24,

its influence can be neglected;

3) the output conductivity Gad in the ohmmeter shunts the input of the operational amplifier 26, in the quasi-bridge - the input of the zero organ

30, its effect, provided that this effect is small, can be neglected.

A feature of the ATaTcTd type conductivity (resistance) measures is that they are used for measuring purposes

with equipotential clamps h and 1 i.e. at

D u

ABOUT,

(32)

resulting in a test voltage of 40 ohmmeter or quasi-bridge

Uac U - D U

U

(33)

equal to the voltage U of the source 24.

Under conditions (3) and (32) 45, the output current ATaTcTd of interest

fifty

a - # - -K O.XiXiXm U / Rp. (34)

R

whence conduction through passage

Gac

55

"C - {j -K O.Xi. ... X, Hmm, (35)

it is directly proportional to the conversion coefficient K, the digital readout O.Kh .... Xt, .... Xm converter 23. the included conductivity Rp of the scale multi-resistor 1 with a virtual set of resistance stages

RP 10 + 1; 10 + 2; ..., 10 + p: ...: 10 + 11; 1 (f 12Ω.

(36) or conductivity

   10 2; ...; Yu r; ...; 10 12cm

(37)

At K -1, reproducible conductivity is determined by the simplest formula

Gac + 0, XiXi. ...; Xm Rp 1. (38)

which when taking into account zooming in Rp

according to (37) is the following

Siv model conductivities:

Gac (1) - 0, XiXiXm cm

r2

Gac (2) O.XiXiXm 1CG cm

Gac (P) 0, XlX (Xm 1 (T CM (39)

1-11

Gac (11) - 0, XiX | Xm 10 CM

Gac (12) 0, XiXiXm

CM

Information array (39) can be at | K | 5th 1 is shifted K times, i.e. in the most general form reproducible conductivity is determined by the formula:

Gac (P, K) 0, XiXiXm G (p.K), (40)

where the scale factor C (p, k) K,

(40a)

In the table. Figure 2 shows the values of the scale factor G (p, K) for possible combinations of Rp 10jx and K of different values according to (37) and (6).

It should be noted that when K is measured in the direction of decreasing, the power dissipation of the simulated conductivity increases. , since the operating (test) voltage of the magazine increases at times with the same operating current.

For example, at K -1 at an operating current of la 0.01 A and a voltage of p 10 V, the power dissipation of the simulated conductivity will be

R u la 10 V x 0.01 A 0.1 W. (41)

At K -0.1 and the same operating currents and the voltage of the op-amp 2, the test voltage

Ucd: K 10 x 10V 100V, (42)

.

5

10

5

0

and the power dissipation of the simulated conductivity is K times smaller according to (35)

R Uad la 100 V 0.01 A - 1 W. (43)

etc., as K. decreases.

When aggregating an inventive device with a control microcomputer, it is possible to convert its low resistance resistance scales and fractional conductivity scales to the corresponding scales of large conductivities with high operating currents and high resistances with high operating voltages, which is of interest in many cases of metrological practice and measuring equipment.

Claims (1)

The claims Resistance and conductivity store containing a controllable large-scale multi-resistor, two current clamps, a voltage follower made in the form of an operational amplifier with a midpoint power supply, a resistive divider made in the form of N equal-series connected in series resistors with (S + 1) intermediate terminals (where N (A -1), and A is the base of the adopted number system), M bit single-pole switches (where M 2: 4), each of which is made in the form of (N + 1) code-controlled keys (or step switches) with (N + 1) outputs, M-bit voltage-to-current converters, each of which is made in the form of an operational amplifier, the common output and non-inverting input of which is combined and connected via a reference resistor to a common bus, the outputs of the bit voltage-to-current converters are connected to the corresponding pole inputs of the bit single-pole switches, the outputs of which are connected to the corresponding intermediate terminals of the resistive divider, the input of which is connected to a third current clamp, which is connected to the output of the voltage follower, the inverting input of which is connected to the output of the resistive divider, characterized in that. in order to increase accuracy and operating range, three there are five potential terminals vt, a two-pole two-way switch and an inverter made on an operational amplifier with a bipolar power supply controlled by a muli resistor and an adjustable resistor, the first current clamp of the magazine is connected to the current output of the first pole of the controlled large-scale multi-resistor, the current output of the second pole which is connected to the second current clamp, the third current clamp is connected to the current output of the common bus of the bipolar power supply of the inverter, the input of which is connected to with a solid current clamp and the first output of the red direction of the bipolar switch, the first pole of which is connected to the second potential terminal, the second potential terminal of the first pole of the controlled scale mute resistor, the first potential terminal of which is connected to the first pole potential terminal, the fifth current terminal is connected to the combined non-inverting input and the output of the midpoint of the power supply of the operational amplifier of the voltage follower, with the fifth potential terminal and the second output of the second direction of the bipolar switch, the second pole of which is connected to the fourth potential terminal and the second potential the output of the second pole of the controlled scale multistor, the first potential output of the second pole of which is connected to the third potential terminal, the first output of the second direction a bipolar switch is connected to a first potential terminal of a common inverter power pole. Table 1 Table 2  9 f dF5 niiTshp- -F / $ 6 / e 3 - // l / (6 ( / 5 O &. - / l 1 Xf t; i  NIITshp- -F / $ 6 / e 3 - // l / V m P 0 f ; Ј l t Fig. / 0109281 1826070