SU1524007A1 - Linear transducer of effective value of a.c. voltage - Google Patents

Abstract

The invention relates to electrical measuring technology and can be used to create analog and digital voltmeters of alternating voltage. The aim of the invention is to improve the accuracy of the conversion with small input signals having a constant component, and increase the sensitivity. For this, a subtractor 14 is inserted in the converter. The input signal is through terminal 3, the adder 13 and the resistor 5 are fed to the imbalance 4, and voltage is applied to it from the output terminal 8 and the low-pass filter 7 through the resistor 6 passing through the subtractor 14. Output the voltage of amplifier 4 causes modulation of the conductivity of field-effect transistors 1 and 2. The input of inverting amplifiers 10 and 11 also receives an input signal, which with the help of resistors 12 and 15 and transistor 2 is transformed into an output voltage It gives the adder 9, and is used as an additional feedback signal. 1 il.

Description

Yu

14

The invention relates to electrical measuring equipment and can be used to create analog and digital voltmeters of alternating voltage, as well as information and measuring systems for various purposes.

The aim of the invention is to improve the accuracy of the conversion with small input signals having a constant component and increase its sensitivity.

The drawing shows a schematic diagram of the device.

The linear converter of the effective value of the alternating voltage contains field-effect transistors 1 and 2, the gates of which are connected to each other, and the drain of the field-effect transistor 2 is connected to the input terminal 3 of the device, the unbalance amplifier 4 connected between the source and the gate of the field-effect transistor 1, resistors 5 and 6 , the first conclusions of which are combined and connected to the source of the field-effect transistor 1, the low-pass filter 7, the output of which is connected to the output terminal 8 of the device and through the first input of the adder 9 to the drain of the field-effect transistor 1, the second input of the adder 9 is connected to the source of the field-effect transistor 1, the input of the inverting amplifier 10 is connected to the source of the field-effect transistor 2, and the output is connected to the input of the low-pass filter 7, the inverting amplifier 11 is connected to the drain of the field-effect transistor 2 and the output through the summing resistor 12 - with the source of the field-effect transistor 2, the first input of the adder 13 is connected to the vnakh terminal 3, the second input of the adder 13 is connected to the first output of the resistor 5, the second output of which is connected to the output of the adder 13, the output of the subtractor 14 is connected to the second the output of the resistor 6, the inputs of the subtractor 14 are connected to the corresponding inputs of the adder 9. The amplifier 10 contains a feedback resistor 15

The Converter operates as follows.

The input of the unbalance amplifier 4 through the adder 13 and the resistor 5 gives the input parchment voltage l g (t). At the same input, the amplitude 4 unbalance through the resistor 6 is fed to the output ps) for example

Tsc ,, with the output of the filter 7 low frequencies. The output voltage of the unbalance amplifier 4 causes the conduction modulation of the field-effect transistor 1 channel. At the same time, the channel conductivity of the field-effect transistor 2 changes.

Since the input voltage of the inverting amplifier 10 through the channel of the field-effect transistor 2 and the connected inverting amplifier 11c connected in parallel with the series-connected resistor 12 also receive the input voltage), the output of the amplifier 10 sets the voltage and, which is proportional to the input voltage conduction channel of the field-effect transistor 2 and resistors 12 and 15.

Resistors 6 and 12 are chosen equal, and it is desirable to use field-effect transistors 1 and 2 placed on the same substrate.

The output of the filter 7 is the output voltage:

h ib

5 and 15;

T is the filter time constant of 7 low frequencies.

Claims (1)

Invention Formula The linear converter of the effective value of the alternating voltage contains the first and second field-effect transistors, the drain of the second field-effect transistor is connected to the input terminal of the device, the unbalance amplifier whose input is connected to the source, and the output is connected to the gate of the first field-effect transistor, the first and second resistors, the first the conclusions of which are combined and connected to the source of the first field-effect transistor, low-pass filter, the output of which is connected to the output. clamping the device and the first input of the first adder, the output of which is connected to the drain of the first field1 transistor, the second input of the first adder is connected to the source of the first field-effect transistor, the source of the second field-effect transistor is connected through the first inverting amplifier to the low-pass filter, DTO51 the ntiB rotary amplifier, the second adder, the first input of which is connected to the input terminal of the device, characterized by it, in order to improve the accuracy of conversion with small input signals having a constant component, and increase the sensitivity, it additionally introduced a subtractor, output which is connected to the second output of the second resistor, the first input of the first adder is connected to the first input of the subtractor, the second 24007 the input of which is connected to the second input of the First adder, the second input of the second cy mater is connected to the first output of the First resistor, the second output of which is connected to the output of the second adder, the input of the second inverting amplifier is connected to the drain of the second field transistor Q torus, the source of which is connected through the summing resistor with the exit. the second inverting amplifier, the gate of the second field-effect transistor is connected to the output of the silytel.