SU1372249A1 - Transducer parameters-to-oscillation period converter - Google Patents

Abstract

The invention can be used to measure non-electric values using sensors included in a two-port circuit. and allows to increase the information content of the output signal. The converter contains a measuring unit, on the base of amplifier 2 with sensor 3 connected to it and two two-pole nicknames 4 and 5, a comparator 7, the input of which is connected to the output of amplifier 2, and the output - to the input of measuring unit 1, and key element 8, connected to the additional inputs of the measuring unit 1. The key element 8 by the signal of the comparator 7 allows one of the two-terminal circuits connected in parallel or in series with the sensor 3 to be bridged, and provides for the formation of pulses The complexity and pause of which depend on the active and reactive parameters of the sensor 3. 2 Cp. f-ly, 3 ill. with e (/)

Description

Fig.)

113

The invention relates to computing and can be used in the measurement of non-electric values using param- etry sensors.

The purpose of the invention is to increase the information content of the output signal.

FIG. Figure 1 shows a transducer circuit with a sensor with a sequential replacement circuit; FIG. 2 is the same with a sensor with a parallel replacement circuit; FIG. 3 - timing diagrams of the converter.

The converter contains a measuring unit 1, made on the amplifier 2, the output of which is the output of the measuring unit 1, and containing a sensor 3 and two two-terminal 4 and 5 connected to the input of the amplifier 2. The output of the measuring unit 1 through the inverter 6 is connected to the input of the regenerative comparator 7 The output of which is connected to the input of the measuring unit 1. A key element 8 is connected to the additional inputs of the measuring unit 1, the control input of which is connected to the output of the comparator 7.

In the case of using sensor 3 with a serial replacement circuit (Fig. 1), it is connected to one of the outputs of the second terminal of the two-terminal 5, and the other output to the output of the amplifier 2. The outputs of the two-terminal 5 are additional inputs of the measuring unit and the input of the second bipolar circuit output 4.

In the case of using sensor 3 with a parallel replacement circuit (Fig. 2), it is connected by one output to the input of amplifier 2, and the second output is the input and at the same time an additional input of the measuring unit 1. The second output of the two-terminal 5 is connected to the output of the amplifier 2, and the second output bipolar 4 is another additional input to measuring unit 1.

The operation of the converter can be considered using the example of converting the parameters of a capacitive type sensor 3 having a replacement circuit in the form of a parallel RC circuit. For example, capacitive moisture meters for oil, liquid level gauges, etc. have such a replacement circuit. Here From right to me

moisture level or liquid level, and R determines the active loss of liquid. In such a replacement circuit, two-terminal 4 is a resistor RO, and two-terminal 5 is a capacitor C.

The device works as follows.

When the power is turned on, the output of amplifier 2, due to deep positive feedback, almost instantly causes a voltage jump, the amplitude V of which is determined by the level of limitation of its linear mode of operation, for example positive (timing diagrams, Fig. 3). As a result, the voltage at the output of the first amplifier 2 is changed as follows (key is open)

25

  V С,

C „K

This voltage is inverted in inverter 6 and fed to one input of the omparator 7. Its output voltage + V is applied to the other input of comparator 7. At the time when the voltage from the output of inverter 6 exceeds V, the output voltage of the comparator 7 abruptly changes. The sign to the opposite, key element 8 is closed. In this case, the voltage at the output of amplifier 2 increases from the value of -V according to the law

V, -V

+ V

2C

(K „-t- R) C,

This voltage is again inverted in inverter 6 and compared with voltage -V at the outputs of comparator 7. At the moment of equality of these voltages, the output voltage of the comparator 7 abruptly changes polarity, the key element 8 opens, the voltage at the output of amplifier 2 decreases from -U

V.

V - V

2 s

RC,

(2)

and the whole process is repeated. Thus, the device works as a relaxation generator.

On the basis of equations (1) and (2), expressions describing the condition of equality of voltages at the outputs of the comparator 7 for an even time interval can be written.

V - V

2C

(K „+ YUS

the key is connected in parallel to a two-port 5. Another two-terminal 4 is connected to the input of amplifier 2 and.

OUTPUT comparator 7.

For a sensor with a series RL replacement circuit, use two coils 4 and 5 inductance L and a resistor RO, respectively.

for an odd (except the first) time interval

-V + v

  V

 With „RC-J

where t

t, the duration of the even and odd time intervals between the trigger times of the comparator 7.

Solving the resulting system of equations (3) and (4), we find

h-t,

 2К „(Co-С). (five)

When converting the parameters of inductive sensor 3 with a parallel replacement circuit of RL-elements

(for example, for eddy current sensors) as the two-port 4 should include the inductor I, and as the two-pole

nick 5 - resistor R. Solving a system of equations describing the condition of the operation of the comparator 7 in the intervals

Sensors of 3 physical parameters, having a sequential replacement scheme of RL and RC elements (e.g., inductive displacement sensors, pressure, conductometric sensors with insulated electrodes, etc.), are connected in series with bipolar 5 to the input and output of amplifier 2, thus negative feedback circuit of amplifier 2 (Fig. 1). With this outputs

15

(four)

20

25

thirty

35

40

45

50

55

Claims (3)

1. A transducer parameter converter during an oscillation period comprising a measuring unit including an amplifier whose output is the output of the measuring unit, a sensor and two two-port devices connected by first terminals to the amplifier input, connected in series with the measuring unit a comparator whose output is connected to the input measuring unit, characterized in that, in order to increase the information content of the output signal, the converter contains a key element connected to the additional inputs of the measuring block, and the control input of the key element is connected to the outputs of the comparator. 2. The converter according to claim 1, which is characterized by the fact that the measuring unit with a serial sensor replacement circuit is made with a sensor connected to the output of the amplifier and the second output of the second two-port, the second one of the first two-pole being the input of the measuring unit, and the first connected the outputs of the two-terminal and the point of connection of the sensor with the second two-terminal form the additional inputs of the measuring unit. 3. The transducer according to claim 1, which is characterized by the fact that the measuring unit with a parallel circuit FIG. g The sensor replacement is made with a sensor connected to the amplifier input, with the other sensor output being the input and at the same time the auxiliary input of the measuring unit, the second output of the first two-pole device forms another auxiliary input of the measuring unit, and the second output of the second two-pole device is connected to the amplifier's output.