SU43937A1 - Method to increase the sensitivity of a galvanometer oscilloscope or other measuring devices - Google Patents

Description

In the existing types of measuring instruments for registering various rapidly changing values, for example, in oscillograph galvanometers, the magnitude of the error is determined by the natural frequency of the instrument's mobile system. To reduce the error, it is necessary to strive to increase the natural frequency of the meter so that it may exceed the frequency of the process being studied as much as possible. However, an increase in the natural frequency of the device reduces its sensitivity, as a result of which it becomes unsuitable for detecting very weak currents, which one encounters in most cases in practice.

3, the method proposed according to the invention is used to increase the sensitivity of the device at resonance, i.e., if the frequency of the process under investigation is equal to the natural frequency of the MOBILE system. The sensitivity of the device increases sharply and can be increased almost IN HUNDREDS.

The process normally studied is not a simple sinusoidal oscillation. a encompasses a significant

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The number of harmonics of different frequencies. The use of a device tuned to the frequency of one of the constituent vibrations is unsuitable since. leads to a distortion of the reproducible curve, since the sensitivity of the device will be different to the different component harmonics of the process under study.

According to the invention, it is proposed to modulate the test voltage with an auxiliary alternating voltage whose frequency is equal to or close to the natural frequency of the moving system of the measuring device. In many cases, the modulation of the auxiliary frequency can be replaced by direct interruption of the process under study with a frequency corresponding to the oscillation frequency of the instrument system.

In the drawing .fig. 1 shows the curve under study; FIG. 2 - curve of auxiliary variable tox; FIG. 3 - the resulting modulated curve.

Practically, the proposed method can be performed differently. For example, if you feed an oscilloscope galvanometer with alternating current from a generator

oscillations, as mentioned, with a frequency equal to the galvanometer natural frequency, the latter will give an image of a curve in the form of a sinusoid of equal amplitude (Fig. 2), which, due to its relatively high frequency, will merge into an image of a light strip located on both sides of the zero line .

In view of the resonance of frequencies, the current consumption by the loop will be insignificant. If we now one of the known ways to modulate the oscillations of a generator with a relatively low frequency under investigation (Fig. 1), then the curve under study, superimposed on the main frequency of its amplitude, will give an image, as indicated in Fig. 3, with the tops of the sinusoids of the generator giving the outlines of the curve under study and can be easily observed on the screen or captured photographically by conventional methods. If it is necessary to apply a zero line (which is obviously going to be right, connecting the top of the generator sinusoids in the absence of a modulated external voltage), you need to move the zero mirror to this place, which will draw a zero line on the top of the main sinusoids, as shown in FIG. 3, in the form of my pr A.

Since the curve under study is obtained in the form of the envelope of the main curve, as can be seen from FIG. 3, the image below line A is redundant and only makes it difficult to decipher the waveform. Therefore, in many cases, for example, when depicting several curves on one screen, it is desirable to remove the second (parasitic) image of the same curve, which can be carried out by various methods, in particular, for example, using a small mobile screen or diaphragm reinforced in front of each galvanometer. and making it possible to cut off any unnecessary part of the curve, as indicated in the same FIG. 3 (section C).

It is clear that the proposed method can be used in any system of measuring devices in which the mobile system has a clearly pronounced corresponding frequency.

fluctuations, regardless of the type of device or its design, or from its destination. The acuteness of the mechanical resonance of a galvanometer can be different and is determined in each individual case, and in the case of using a few calmed vibrators, one can also obtain a sensitivity many times higher than its normal deflection.

In addition to performing modulation directly in the current itself, supplying the galvanometer, the latter can be carried out in various other ways, in particular, for example, by applying the tested alternating voltage to the grid of the carrier frequency oscillator corresponding to the frequency of the galvanometer included in the generator anode circuit. Thanks to this scheme, a complete lack of consumption is achieved and the question of additional tube amplification is solved without introducing the distortions that each of the commonly used amplifying circuits inevitably introduces into the oscilloscope readings.

As mentioned above, in many cases, instead of auxiliary AC current, a periodic interruption of the process under investigation can be applied at a frequency corresponding to the natural frequency of the moving system of the measuring device. A similar method can be used in the study of any electrical process, regardless of its nature.

The subject matter of the invention.

Claims (4)

1. A method of increasing the sensitivity of a galvanometer of an oscilloscope or other measuring devices, characterized in that the voltage under investigation is modulated by an auxiliary voltage of currents of such a higher frequency so that it is in resonance with the oscillation frequency of the oscilloscope's moving part. 2. Modification of the method according to claim 1, characterized in that instead of an auxiliary voltage modulated by the voltage under test, the latter are periodically interrupted. with a frequency equal to the natural frequency of oscillation of the oscilloscope. 3. An apparatus for carrying out the method according to claim 1, characterized by the use of a lamp generator tuned to resonance with the frequency of oscillations of the moving part of the oscilloscope, the oscillations of which generator are modulated by the voltage under study. 4. In the device according to claim. 1, the use of stabilization of the frequency of the generator according to one of the known methods. -WITH- .