MATHEMATICAL SIMULATION OF A DEVICE WITH FREQUENCY OUTPUT FOR MEASUREMENT OF HUMIDITY

The device for measuring humidity with a moisture-sensitive resistive element HR202 has been developed. The self-generating transducer is designed as a hybrid integrated circuit based on a bipolar transistor VT1 and a field-effect two-gate transistor VT2. The negative differential resistance, which is formed by the parallel connection of the impedance with a capacitive component at the collector electrodes of the bipolar transistor VT1, the drain of the field-effect transistor VT2 and inductance L1, leads to the occurrence of electrical oscillations in the circuit. When exposed to moisture on the sensitive resistive element RW, the capacitive component of the impedance at the electrodes of the transistor structure changes, which causes an effective change in the frequency of the oscillatory circuit. On the basis of mathematical modeling of electrical characteristics, analytical expressions for the transformation function and the sensitivity equation are obtained. It has been experimentally established that an increase in the ambient temperature in the range of relative humidity W = 30 ÷ 85% leads to an expansion of the generation range of the autogenerating humidity transducer, as well as to an increase in the sensitivity of the device to the measured value. The generation range of the autogenerating humidity transducer at a temperature of T = 20 °C acquires a value of 823 kHz (the average value of the sensitivity is 16.18 kHz /%), and at a temperature of T = 50 °C – 1323 kHz (the average value of the sensitivity is 29.10 kHz / %). To confirm the theoretical results of circuit solutions developed device in the computer modeling of LTSpice modeling environment. The studies were carried out at different temperatures (20°C, 30°C, 40°C, 50°C) in the range of change in the resistance of the moisture-sensitive resistive element from 1750 kOhm to 2.1 kOhm, which corresponds to an increase in the value of the relative air humidity from 30 % to 90 %. The results of theoretical and experimental studies have shown that at the output there are periodic oscillations device for measuring the humidity rate which increases with increasing values ​​of relative humidity. The obtained theoretical and experimental studies are in good agreement, the relative error does not exceed 2.5%.

MATHEMATICAL SIMULATION OF A DEVICE WITH FREQUENCY OUTPUT FOR MEASUREMENT OF HUMIDITY

The device for measuring humidity with a moisture-sensitive resistive element HR202 has been developed. The self-generating transducer is designed as a hybrid integrated circuit based on a bipolar transistor VT1 and a field-effect two-gate transistor VT2. The negative differential resistance, which is formed by the parallel connection of the impedance with a capacitive component at the collector electrodes of the bipolar transistor VT1, the drain of the field-effect transistor VT2 and inductance L1, leads to the occurrence of electrical oscillations in the circuit. When exposed to moisture on the sensitive resistive element RW, the capacitive component of the impedance at the electrodes of the transistor structure changes, which causes an effective change in the frequency of the oscillatory circuit. On the basis of mathematical modeling of electrical characteristics, analytical expressions for the transformation function and the sensitivity equation are obtained. It has been experimentally established that an increase in the ambient temperature in the range of relative humidity W = 30 ÷ 85% leads to an expansion of the generation range of the autogenerating humidity transducer, as well as to an increase in the sensitivity of the device to the measured value. The generation range of the autogenerating humidity transducer at a temperature of T = 20 °C acquires a value of 823 kHz (the average value of the sensitivity is 16.18 kHz /%), and at a temperature of T = 50 °C – 1323 kHz (the average value of the sensitivity is 29.10 kHz / %). To confirm the theoretical results of circuit solutions developed device in the computer modeling of LTSpice modeling environment. The studies were carried out at different temperatures (20°C, 30°C, 40°C, 50°C) in the range of change in the resistance of the moisture-sensitive resistive element from 1750 kOhm to 2.1 kOhm, which corresponds to an increase in the value of the relative air humidity from 30 % to 90 %. The results of theoretical and experimental studies have shown that at the output there are periodic oscillations device for measuring the humidity rate which increases with increasing values ​​of relative humidity. The obtained theoretical and experimental studies are in good agreement, the relative error does not exceed 2.5%.

New Electronic Interface Circuits for Humidity Measurement Based on the Current Processing Technique

The paper describes a new electronic conditioning circuit based on the current-processing technique for accurate and reliable humidity measurement, without post-processing requirements. Pseudobrookite nanocrystalline (Fe2TiO5) thick film was used as capacitive humidity transducer in the proposed design. The interface integrated circuit was realized in TSMC 0.18 μm CMOS technology, but commercial devices were used for practical realization. The sensing principle of the sensor was obtained by converting the information on environment humidity into a frequency variable square-wave electric current signal. The proposed solution features high linearity, insensitivity to temperature, as well as low power consumption. The sensor has a linear function with relative humidity in the range of Relative Humidity (RH) 30-90 %, error below 1.5 %, and sensitivity 8.3 x 1014 Hz/F evaluated over the full range of changes. A fast recovery without the need of any refreshing methods was observed with a change in RH. The total power dissipation of readout circuitry was 1 mW.

Design optimization and stability enhancement of modified inter-digital capacitive humidity transducer with cobalt ferrite nanoparticles as dielectric

A modified inter-digital capacitive (IDC) transducer for relative humidity (RH) measurement is fabricated by coating a thick film of polyvinyl alcohol (PVA) on the structure. The effective capacitance of the sensor, measured at 1MHz, increases with RH at room temperature. The RH sensing characteristics of PVA coated IDC transducer are analysed in terms of its sensitivity, dynamic range, frequency response, repeatability and recovery time. It is found that the stability of such a PVA based RH transducer improves remarkably by diffusing nanoparticles of CoFe2O4 in the PVA layer. A standard deviation of ± 0.05 and ± 0.01 for a sensitive layer with pure PVA and PVA-CoFe2O4 combination respectively results in a measurement error of ± 0.005 and ± 0.003.

Rancang Bangun Sistem Observasi Keadaan Atmosfer Bumi Menggunakan Drone

Observation of atmospheric data is an integral part of research activities in fields related to weather and climate. The technology that has developed today has measured environmental parameters vertically using atmospheric broadcasting technology, radio, a device that can be flown by atmospheric balloon vehicles that can measure vertical atmospheric parameters and transmit data via radio. Therefore, this study makes the atmosphere that is temperature, humidity, air pressure, wind and GPS. By using DHT11 sensor as temperature and humidity transducer, BMP280 sensor as an air pressure transducer, HMC5883l as a wind direction transducer, MQ135 as a Carbon Dioxide gas transducer, and GPS as the purpose of the sensor data will be stored and sent via 3DR radio telemetry.

Research of Multi-Channel Hygrothermoscope Acquiring System

The paper introduces a multipoint remote Hygrothermoscope monitoring system based on the MAX485 bus. The system of remote multipoint temperature control is composed of the host machine and slave machine; the host system for display and control, the slave system is responsible for collecting temperature data. Between master machine and slave machine communicate through the RS-485 bus, can realize the distant control room of the scene monitoring. The STC89C54 MCU is used as the controller and DHT11 is used as the temperate and humidity transducer. The hardware and software of the system are outlined. The system has realized multiple measuring points, easy expansion, and high reliability, anti-interference. The whole system has the advantages of simple circuit, reliable, and can be used for measuring temperature, humidity, temperature of building air conditioning control temperature and humidity monitoring and other fields.

Design of Wireless Temperature and Humidity Sensor Based on NRF24L01

According to the development of the Internet of things, a wireless cognitive transducer based on humidity-sensitive capacitor was designed. The ambient temperature and humidity are measured by temperature &humidity transducer which transfers the capacity into frequency signal with the help of RC oscillation, followed by the frequency with MSP430 SCM and the humidity accordingly. Thermal sensitive resister of the negative temperature system is used to measure the temperature. When measuring, the humidity can be compensated by temperature data, thus ensuring higher precision and stability of humidity measuring. The measured data are sent out by NRF24L01 through communication protocol to accomplish distant data collection of temperature and humidity, which foretells a bright prospect.