SU1056067A1 - Null detector - Google Patents

Description

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The invention relates to a measurement technique and can be used in monitoring the parameters of complex-impedance resistors. Also in AC bridges.

A null-organt containing a rectifier and a key connected to the input buses is known, in which the outputs of the keys are connected to the output bus through a comparison unit, and the corresponding control inputs of the keys are connected to another input bus 1 through the switch.

The disadvantage of this device is low accuracy.

Closest to the invention is a null organ containing a comparison unit, two inputs of which are connected to the input buses through corresponding keys, and two control units, each of which is connected between one input bus and the control. the key input connected to another input bus 23.

The device, due to the need for expansion in the comparison circuit of one of the pulses arriving at it, has a low accuracy comparison of the amplitudes of alternating voltages.

The purpose of the invention is to improve the accuracy of comparison of variable voltages.

To achieve this goal, a trigger, an adder and an integrator, sub-, connected to the output of the adder, whose inputs are connected to the outputs of the keys, are entered into the null body containing the first and second keys and control blocks connected to the first and second input buses, respectively. connected by control inputs to the output of the trigger, the inputs of which are connected to the outputs of the blocks. management,

FIG. 1 shows a block diagram of a null organ; in fig. 2 - Diagram 1Y

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The zero-body contains the control units 1 and 2, the trigger 3, the keys 4 and 5, the adder 6, the integrator 7. The inputs of the keys 4 and 5 and the inputs of the control blocks 1 and 2 are connected respectively to the input buses 8 and 9. The outputs of the control blocks {

hooked up to the trigger inputs 3, the output g of which is connected to the control keys of keys 4 and 5. The outputs of the keys are connected to the inputs of the adder, to the output of which an integrator is connected, the output of which is connected to the output bus.

The zero-body works as follows.

Comparison voltage voltages are applied to the input buses 8 and 9.

0 U-, and u2 (Fig. 2a and 26). Let be,. for example, U S2- When the amplitude of the input voltages changes in the direction of their decrease at the moment of their transition through the zero level, the blocks 1 and 2 of the control

5 produce a short voltage pulse at the output; First, when the voltage amplitude decreases, the zero voltage level Ug goes; at that, the output pulse of the control unit 2

Q starts trigger 3 (Fig. 2c). The output voltage of this trigger will be opened with keys 4 and -5 and to their output, i.e. The inputs of the adder receive input voltages and and u2 (Fig. 2d). In the moment

5 crossing the zero voltage level and at the output of the control unit 1 a voltage pulse is generated, with which the trigger 3 returns: to the initial state (Fig. 2c). The keys 4 and 5 are closed and the compared voltages to the inputs of the adder b are no longer applied. Thus, at the output of the adder, a voltage (Fig. 2d) is formed, varying in a sinusoidal law, a constant component

5 of which (Fig. 2d), which is allocated with the help of the integrator 7, is determined by the difference in magnitudes of the amplitudes of the compared voltages. When the voltage Uj is exceeded, the voltage U;

0 the polarity of the voltage at the output of the integrator 7 is negative, when the voltage U is exceeded, the voltage and the polarity of the voltage at the integrator's output is positive. With

5 equality of the compared voltages is the voltage at the integrator output, i.e. at the output of the null organ, is zero.

Eliminating the need to expand (memorize) the compared signals allows for improved device accuracy.

Fig2

Claims (1)

ZERO-ORGAN containing the first and second keys and control units connected to the first and second input buses, respectively, characterized in that, in order to improve the accuracy of comparing variable voltages, a trigger, adder and integrator connected to the adder output are introduced into it whose inputs are connected to You are a, moves keys connected upravlya- ¹ yuschimi inputs to the output of flip-flop having inputs connected to the outputs of the control units. Fig 1