SU430505A1 - FREQUENCY RESISTANCE CONVERTER - Google Patents

Description

one

The invention relates to the field of electrical measuring equipment.

From; frequency resistance converters are known on the basis of structures with switching of the direction of integration, characterized by simplicity of circuit design and sufficiently high accuracy and accuracy characteristics. In a number of cases, when measuring temperature with TepMOioo, the primary converter is placed at a considerable distance from the frequency converter and is connected via a cable link. With this, due to the presence of the reactive component of the line, the accuracy of the transmitter's source is significantly deteriorated.

The aim of the invention is to increase the accuracy of the conversion in the case of a sensor being connected via a cable line.

SILTS.

This is achieved by connecting the output of the comparison device through an integrating RC circuit to the non-inverting input of the integrating amplifier and through a differential amplifier of a direct current with 100% negative feedback to the divider from the sample and measured resistances.

The drawing shows the scheme of the proposed Converter.

The converter includes an integrating amplifier / s capacitive negative feedback, a comparison device 2, a divider 3 of convertible and exemplary resistances, a differential amplifier 4 of direct current with 100% - | Noah negative feedback and an integrating RC circuit 5.

In the process of converter operation, the voltage differences from the output of the comparator 2 device through the differential amplifier 4 of direct current with 100% negative feedback go to the divider 3 from the transformed and reference resistance and through the integrating RC-dets 5 to the noninventing input integrating amplifier 1. The linearly varying voltage from the output of the integrating amplifier (compared to the output voltage of the divider 5) and at the time of the specified equalization, the comparison device operates 2. At this time varies its sign you .HOD1NOGO voltage and, accordingly, the sign of the slope linearly varying voltage of the integrating amplifier 1. One half of the converter is determined from the expression

2Uo Up r

Rf + Ko RC 2

where Ro is the value of the model resistance;

Rjf is the value of the resistance being preformed;

UQ - Kalnbrova’s reference level of voltage from the output of the device compared to 2;

C is the time constant of the integrating KS circuit 5;

L

T

the duration of the half period of output oscillations of the converter. Taking into account the TOipo, that in the next half-perimeter of the converter, the character is completely identical, the output frequency is derived from the expression

1 g

()

0

ARC

The last expression indicates that the conversion function of the device under consideration is linear, and its steepness is determined by the constant time of the integrating RC circuit and the value of the reference resistance.

In the case of connection of a transverse transducer through a cable line, the processes in the circuit practically remain the same. the only difference is that the changes in the national input transducer terminals are exponential.

In order to preserve the linearity of the conversion function, it is necessary to correspond to the following sample: M: o & frequency frequency range of the converter, so that the transient processes recharge the reactive elements of the line into (Each half-period of the converter operation would almost have time to start)

Subject invention

A matching frequency converter containing an integrating amplifier with a capacitive negative negative feedback,

device of the device and matching device, made on the basis of differential amplifiers - direct current, divider of convertible and model resistance, connected to one input of the device

Comparison whose other input is connected to the output of an integrating amplifier, characterized in that, in order to increase the conversion accuracy if there is a cable line, 1 OUTPUT of the comparison device is connected to the non-inverting input of the integrating amplifier through and through the integrating RC circuit. „Differential amplifier

direct current oo 100% negative

o, b | taty communication - to the divider from the model and measurable resistances.