This article discusses the modeling of a 4th order Butterworth bandpass filter, with the Sallen-Key topology, composed of 2 stages with a bandwidth from 31.5 Hz to 8.5 kHz, designed to work as part of a digital noise level meter . Modeling was carried out in a modern computer-aided design package Filter Design Tool from Texas Instruments. The simulation results are presented, a conclusion is made about the correspondence of the parameters of the simulated filter to the calculated ones. The filter has a satisfactory quality factor, amplitude deviation in the passband, is quite simple and economically acceptable from the point of view of its implementation.

Keywords: noise meter, bandpass filter, Butterworth filter, Sallen-Key topology, modeling, CAD

The author carried out the development of the measuring unit of the intellectual system for the protection of the territory. Based on the review of devices of a similar purpose, a block diagram of the device was developed. A functional diagram of the developed device based on the block diagram has been developed and described. The description of the computer experiment on modeling the operation of the input block of the circuit in Micro-Cap, its results and analysis is given.

Keywords: measuring unit, intelligent system, modeling, vibration, triboelectric sensor

The article describes the development of an electrical impedance tomography module with the following characteristics: number of electrodes n = 16; injected current I = 5 mA ± 2%; permissible error of the measuring channel δadm = 2%; injected current frequency f = (10…400) kHz; resulting voltage on the injection electrodes U ≤ 12 V; the shape of the injected current is sinusoidal, triangular, rectangular; USB data interface. A functional diagram of the device has been developed and described. Simulation of a current source with a connected load in the MicroCap software package was carried out

Keywords: electrical impedance tomography, ventilator, disease diagnostics, modeling

in the course of designing a device for measuring the instantaneous velocity of plasma in an electrodynamic accelerator, a block diagram of the implementation of the developed method was developed. A mathematical description of the calculation of the instantaneous velocity of plasma in an electrodynamic accelerator is presented. The choice of a realizable method for measuring the instantaneous velocity of plasma in an electrodynamic accelerator using a differential-total-ratiometric coordinate function and approximating the position sensor signal by an inverse-exponential function is substantiated. Simulation of the computing unit of the device in the Micro-Cap environment has been completed.

Keywords: measuring device, electrodynamic accelerator, plasma velocity, differential sensors

In this article, a prototype of a multichannel digital ammeter will be considered. The structural scheme and algorithm of the program for the microcontroller is presented.

Keywords: ammeter, digital ammeter, multichannel digital ammeter, prototype ammeter, Hall sensor, Hall effect

Need for measurement of weak signals exists in many fields of science and technology. An example of such area is the optical spectroscopy of substances with low concentration of the centers of coloring. Use of devices of synchronous detecting allows to solve this problem. The need for the reliable, inexpensive and convenient device in use defines interest in development of the new schemes meeting these requirements. In this work the new scheme of the programmable synchronous detector with use of sequence filters and the digital phase shifter is offered. Advantages of the offered scheme is the high sensitivity and low cost in comparison with commercial versions of synchronous detectors.

Keywords: lock in amplifier ,sequence filter, detecting, phase shifter