SU563639A1 - Four-arm measuring bridge - Google Patents

Description

The voltage at the output of block 6 is equal to the voltage drop at the shoulder ad containing the measurement object 4, so that this voltage drop includes the power supply diagonal ab in series with the voltage of the f / e source 1. Then the voltage at the power diagonal ab

-and ,, (1)

and.,

where is the resistance of the object 4 measurement; Cs-resistance of the model element 5.

Output voltage of the measuring bridge (voltage across the measuring diagonal cd) At / equal to

I + YS-RX Lgg / g,

sh

1, g, V-H (

1 - «1 / 2U

where 1 is the resistance of model element 2;

3 --- and U2-conductivity sample AZA2

output elements 5 and 3, respectively.

From expression 2 it can be seen that the output voltage of the bridge linearly depends on the resistance of the element of the shoulder, to which the inputs of the isolation unit 6 are connected, and the conductivity of the element of the adjacent shoulder. In this case, a linear relationship is provided without introducing a contour adjustment contour with a high gain and in a much simpler way than in known devices.

If the resistance values Ri, Rz, Rz (resistances of elements 2, 3, 5) are chosen in such a way that

one.-.

jrH

R.

where r is the nominal value of the resistance RX (the resistance of the object to be measured), then the output signal of the bridge is directly proportional to the relative deviation of the drop ratio Rx from its nominal steady-state value.

To obtain a linear dependence of the down voltage on the conduction of the arm with a variable passive value, for example

measures of ultrasound conductivity:

needed in

v

power supply diagonal Consistently with the power source f / g voltage, turn on the voltage equal to the voltage drop across the shoulder adjacent to the shoulder ad, i.e. equal to the voltage drop across the shoulder bd. For this, the inputs of block 6 are connected to points b and d. In this case, the output voltage of the bridge linearly depends on the conductivity of UX and is directly proportional to the relative deviation

YX conductivity from its nominal value.

The resistances (conductors) forming the branches of the bridge can be ohmic, capacitive and complex.

In the general case, when the elements are 2, 3, 4, 5-complex impedances, and Ua is the alternating current voltage, the invention allows the construction of meters of complex quantities with good convergence. In this case, the inputs of the decoupling unit 6 are connected to a shoulder containing an impedance with an adjustable parameter, or to a shoulder with a shoulder containing a commixel conductivity with an adjustable

by parameter. Then the output is the bridge voltage linearly with respect to the adjustable parameters, which ensures good convergence.

Claims (2)

1. Copyright-USSR certificate number 241528, "l. G 01R 17/10, 06.12.67. , 2. US Patent No. 3416076, cl. 324-57, 1968.