UA137280U - OPTICAL GAS CONCENTRATION METER WITH FREQUENCY OUTPUT - Google Patents

Abstract

The optical gas concentration meter with frequency output consists of a coherent source of optical radiation, which is optically connected through a series-mounted in the direction of the beam of the cell with the photodetector of the scattered radiation flux. Additionally, two bipolar transistors, a diode, a field-effect transistor, a capacitor, a limiting capacitor, a resistor and two DC voltage sources were introduced. The first DC source is connected to a coherent source of optical radiation in the forward direction, which is in series optically connected, via a cuvette, to the photodetector of the scattered radiation flux.

Description

The useful model belongs to the field of control and measurement technology and can be used as a gas sensor in devices for automatic control of technological processes.

A known device for measuring gas concentration, consisting of a source of coherent radiation, which is optically connected through a light splitter, a cuvette, a diaphragm and a lens installed in series with a photodetector, which is connected through a photoamplifier to the first input of a logarithmic amplifier, the second input of which is connected with a photoreceiver of the reference radiation flow, and the output is connected to the reference device (patent

USA Mo 4408880, MPKye 01 M 21/00, 19831.

The disadvantage of such a device is low accuracy and complexity, due to the presence of a photoamplifier and a logarithmic amplifier, which create zero shift errors, change transmission coefficients and complicate the design.

The closest analogue is a device for measuring gas concentration (see USSR patent

Mo1716399, MPKye S01M 01/21, 1989|. The device consists of a coherent source of optical radiation, which is optically connected through a light-splitting element, a cuvette, a diaphragm, a lens with a photodetector of the scattered radiation flow, which is connected to the input of the comparator and to the first output of the switch, the second output of which is connected to the is connected to the bus of zero potential, the information input is connected to the output of the photodetector of the reference radiation flux, and the control input is connected to the output of the comparator and the input of the low-pass filter, the output of which is connected to the reference device.

The disadvantage of such a device is low sensitivity due to amplification of inherent noise of semiconductor elements.

The basis of a useful model is the task of creating an optical meter of gas concentration with a frequency output, in which, due to the introduction of new elements and connections between them, the gas concentration is converted into frequency, which leads to an increase in sensitivity, as well as the accuracy of gas concentration measurement in the area of small values , which contributes to the expansion of the field of use of the device.

The problem is solved by the fact that in an optical gas concentration meter with a frequency output, which consists of a coherent source of optical radiation, which

Zo is optically connected through a cuvette installed in series in the direction of the beam, with a diffuse radiation photodetector, two bipolar transistors, a diode, a field-effect transistor, a capacitor, a limiting capacitor, a resistor and two sources of constant voltage are introduced, and the first source of constant voltage is connected to a coherent source of optical radiation in the forward direction, which is optically connected in series, through a cuvette, with a photodetector of the scattered radiation flux, the first terminal of which is connected to the drain of the field-effect transistor, with the second terminal of the diode, the first terminal of which is connected to the ground, with the emitter of the first bipolar transistor, the base of which is connected to the drain of the field-effect transistor, the collector of the first bipolar transistor is connected to the output of the device, to the second terminal of the scattered radiation flux photodetector, to the first terminal of the capacitor, to the emitter of the second bipolar transistor, the base of which is connected with the second terminal of the capacitor and with the first terminal of the res istor, the second output of which is connected to the collector of the second bipolar transistor, to the first output of the limiting capacitor, to the first output of the second source of constant voltage, the second output of the limiting capacitor and the second output of the second source of constant voltage are connected to ground.

The drawing shows a scheme of an optical gas concentration meter with a frequency output.

The optical gas concentration meter with a frequency output consists of a coherent source of optical radiation 2, which is optically connected through cuvettes 3 installed in series in the direction of the beam, with a photodetector of the scattered radiation flux 4, the first 5 and the second 9 bipolar transistors, diode b, field-effect transistor are introduced 7, the capacitor 8 and the limiting capacitor 11, the resistor 10, the first 1 and the second 12 constant voltage sources, and the first constant voltage source 1 is connected to the coherent source of optical radiation 2 in the forward direction, which is optically connected in series, through the cuvette 3 , with a photodetector of the scattered radiation flux 4, the first terminal of which is connected to the drain of the field-effect transistor 7, with the second terminal of the diode b, the first terminal of which is connected to the ground, with the emitter of the first bipolar transistor 5, the base of which is connected to the drain of the field-effect transistor transistor 7, the collector of the first bipolar transistor 5 is connected to the output of the device, with the second output of the photo receiver of scattered radiation flow 4, with the first terminal of the capacitor 8, with the emitter of the second bipolar transistor 9, the base of which is connected to the second terminal of the capacitor 8 and to the first terminal of the resistor 10, the second terminal of which is connected to the collector of the second bipolar transistor 9, with the first output of the limiting capacitor 11, with the first output of the second constant voltage source 12, the second output of the limiting capacitor 11 and the second output of the second constant voltage source 12 are connected to ground.

An optical gas concentration meter with a frequency output works as follows.

At the initial moment of time, there is no gas in cuvette 3. The first source of constant voltage 1 feeds the coherent source of optical radiation 2, increasing the voltage of the second source of constant voltage 12 to the value when the electrodes of the bipolar transistor 5 and the field-effect transistor 7 produce a negative resistance, which leads to the occurrence of electrical oscillations in the circuit, which is formed by the parallel inclusion of total resistance with a capacitive component on the electrodes of bipolar transistor 5, field-effect transistor 7 and total resistance with an inductive nature on the emitter-collector electrodes of the second bipolar transistor 9.

The value of total resistance with an inductive nature is determined by resistor 10 and capacitor 8. Diode 6 provides power to the first bipolar transistor 5 and field-effect transistor 7.

The limiting capacitor 11 prevents the passage of alternating current through the second source of constant voltage 12. When gas enters the cuvette C, a different amount of optical energy will fall on the photoreceptor of the scattered radiation flux 4 and its resistance will change, and therefore the value of the capacitive component of the total resistance at the electrodes of the first bipolar transistor 5 and field-effect transistor 7, this, in turn, causes a change in the frequency of the generated oscillations.

Claims (1)

USEFUL MODEL FORMULA An optical gas concentration meter with a frequency output, which consists of a coherent source of optical radiation, which is optically connected through a cuvette installed in series along the direction of the beam with a photodetector of the scattered radiation flux, which is distinguished by the fact that two bipolar transistors, a diode, a field-effect transistor, are additionally introduced. capacitor, limiting capacitor, resistor and two DC sources From the voltage, and the first source of constant voltage is connected to a coherent source of optical radiation in the forward direction, which is optically connected in series, through a cuvette, to a photodetector of the scattered radiation flux, the first terminal of which is connected to the drain of the field-effect transistor, to the second terminal diode, the first terminal of which is connected to the ground, to the emitter of the first bipolar transistor, the base of which is connected to the drain of the field-effect transistor, the collector of the first bipolar transistor is connected to the output of the device, to the second terminal of the photodetector of the scattered radiation flux, to the first terminal of the capacitor , with the emitter of the second bipolar transistor, the base of which is connected to the second terminal of the capacitor and the first terminal of the resistor, the second terminal of which is connected to the collector of the second bipolar transistor, with the first terminal of the limiting capacitor, with the first terminal of the second constant voltage source, the second terminal limiting capacitor and the second terminal of the second source is constant voltages are connected to ground. Vikh Z, shi | who k her lake; yes and and their Mr: she she ney ;