Measurement of the level of radioactive background is carried out using a special device - a dosimeter. It can be purchased in a specialized store, but DIYers will be attracted by another option - to make a dosimeter with their own hands. A household modification can be assembled in several variations, for example, from improvised means or with the installation of an SBM-20 counter.
Naturally, it will be rather difficult to assemble a professional or multifunctional dosimeter. Household portable or personal devices register beta or gamma radiation. The radiometer is designed to investigate specific objects and read the level of radionuclides. In fact, a dosimeter and a radiometer are two different devices, but household versions often combine both the first and the second. Fine terminology plays a role only for specialists, therefore even combined models are called in general terms - a dosimeter.
By choosing one of the proposed schemes for assembly, the user will receive the simplest device with low sensitivity. There is still a benefit in such a device: it is capable of registering critical doses of radiation, this will indicate a real threat to human health. Despite the fact that a homemade device is many times inferior to any household dosimeter from a store, to protect your own life it is quite usable.
Before choosing one of the assembly schemes for yourself, read the general recommendations for the manufacture of the device.
- For a device of their own assembly, choose 400 volt meters, if the converter is designed for 500 volts, then you need to adjust the setting of the feedback circuit. It is permissible to choose a different configuration of zener diodes and neon lamps, depending on which dosimeter circuit is used during manufacture.
- The output voltage of the stabilizer is measured with a voltmeter with an input resistance of 10 MΩ or more. It is important to check that it is actually equal to 400 volts, charged capacitors are potentially dangerous to humans, despite their low power.
- Several small holes are made in the housing near the counter for beta radiation penetration. Access to high voltage circuits must be excluded, this must be taken into account when installing the device in the case.
- The circuit of the measuring unit is selected based on the input voltage of the converter. The connection of the unit is carried out strictly with the power off and the discharged storage capacitor.
- When natural radiation background a homemade dosimeter will give about 30 - 35 signals in 60 seconds. Exceeding the indicator indicates high ion radiation.
Scheme No. 1 - elementary
To design a detector for detecting beta and gamma radiation “quickly and easily”, this option is the best fit. What you need before construction:
- a plastic bottle, or rather a neck with a lid;
- a tin can without a lid with processed edges;
- ordinary tester;
- a piece of steel and copper wire;
- transistor kp302a or any kp303.
For assembly, you need to cut off the neck from the bottle so that it fits snugly into the can. A narrow, tall can, like from condensed milk, is best suited. Two holes are made in the plastic cover, where you need to insert the steel wire. One edge of it is bent with a loop in the shape of the letter "C" so that it firmly holds on to the lid, the other end of the steel bar should not touch the can. After the cover is screwed on.
The leg of the KP302a shutter is screwed to the loop of the steel wire, and the tester terminals are connected to the drain and source. Around the jar, you need to wrap a copper wire and fix it with one end to a black terminal. A capricious and short-lived field-effect transistor can be replaced, for example, connect several others according to the Darlington circuit, the main thing is that the total gain should be equal to 9000.
Homemade dosimeter is ready, but you need it calibrate. For this, a laboratory source of radiation is used, as a rule, the unit of its ion radiation is indicated on it.
Scheme No. 2 - meter installation
In order to assemble a dosimeter with your own hands, a regular one will do. counter SBM-20 - you will have to buy it in a specialized radio parts store. An anode - a thin wire - passes through the sealed cathode tube along the axis. The interior space is filled with gas at low pressure, which creates an optimal environment for electrical breakdown.
The voltage of SBM-20 is about 300 - 500 V, it must be adjusted so as to exclude arbitrary breakdown. When a radioactive particle hits, it ionizes the gas in the tube, creating a large number of ions and electrons between the cathode and anode. Similarly, the counter is triggered for each particle.
It is important to know! For a homemade device, any meter designed for 400 volts is suitable, but SBM-20 is the most suitable, you can purchase the popular STS-5, but it is less durable.
Dosimeter circuitconsists of two units: an indicator and a network rectifier, which are assembled in plastic boxes and connected with a connector. The power supply is connected to the network for a short period of time. The capacitor charges up to 600 W and powers the device.
The unit is disconnected from the network and from the indicator, and the connectors are connected to the contacts high impedance phones... A good quality capacitor should be chosen to prolong the operating time of the dosimeter. A homemade device can function for 20 minutes or more.
Technical features:
- the rectifier resistor is optimally selected with a dissipative power of up to 2 W;
- capacitors can be ceramic or paper, with the appropriate voltage;
- you can choose any counter;
- eliminate the possibility of touching the resistor contacts with your hands
Natural background radiation will be recorded as rare signals in the phones, the absence of sounds means that there is no power.
Scheme No. 3 with a two-wire detector
It is possible to construct a homemade dosimeter with a two-wire detector; this requires a plastic container, a feed-through capacitor, three resistors and a single-channel damper.
The damper itself reduces the vibration amplitude and is installed behind the detector, directly next to the feed-through capacitor, which measures the dose. For such a design, only resonant rectifiers, but expanders are practically not used. The device will be more sensitive to radiation but will take longer to assemble.
There are other schemes for making a dosimeter yourself. Many variations have been developed and tested by radio amateurs, but most of them are based on the circuits described above.
Whether we like it or not, radiation has firmly entered our lives and is not going to go away. We need to learn to live with this, both useful and dangerous, phenomenon. Radiation manifests itself as invisible and imperceptible radiation, and it is impossible to detect them without special devices.
A bit of radiation history
X-rays were discovered in 1895. A year later, the radioactivity of uranium was discovered, also in connection with X-rays. Scientists realized that they were faced with completely new, hitherto unseen natural phenomena. Interestingly, the phenomenon of radiation was noticed several years earlier, but they did not attach importance to it, although Nikola Tesla and other employees of the Edison laboratory received burns from X-rays. The harm to health was attributed to anything, but not to the rays, with which the living has never encountered in such doses. At the very beginning of the 20th century, articles began to appear on the harmful effects of radiation on animals. This, too, was not given any importance until the sensational story of the "radium girls" - workers of the factory that produced luminous watches. They just moistened the brushes with the tip of their tongue. The terrible fate of some of them was not even published, for ethical reasons, and remained a test only for the strong nerves of doctors.
In 1939, physicist Lisa Meitner, who, together with Otto Hahn and Fritz Strassmann, refers to the people who divided the uranium nucleus for the first time in the world, inadvertently blurted out about the possibility of a chain reaction, and from that moment a chain reaction of ideas about creating a bomb, namely a bomb, and not "Peaceful atom", to which the bloodthirsty politicians of the 20th century, of course, would not give a penny. Those who were "in the know" already knew what this would lead to and the atomic arms race began.
How the Geiger-Muller counter appeared
The German physicist Hans Geiger, who worked in the laboratory of Ernst Rutherford, in 1908 proposed the principle of operation of the counter of "charged particles" as a further development of the already known ionization chamber, which was an electric condenser filled with gas at low pressure. It was used by Pierre Curie since 1895 to study the electrical properties of gases. Geiger had the idea to use it to detect ionizing radiation precisely because these radiation had a direct effect on the degree of ionization of the gas.
In 1928, Walter Müller, under the direction of Geiger, creates several types of radiation counters designed to register various ionizing particles. The creation of counters was a very urgent need, without which it was impossible to continue the study of radioactive materials, since physics, as an experimental science, is unthinkable without measuring instruments. Geiger and Müller purposefully worked on the creation of counters that are sensitive to each of the types of radiation open to that: α, β and γ (neutrons were discovered only in 1932).
The Geiger-Muller counter has proven to be a simple, reliable, cheap and practical radiation detector. Although it is not the most accurate instrument for studying particular types of particles or radiation, it is extremely suitable as a device for general measurement of the intensity of ionizing radiation. And in combination with other detectors, it is used by physicists for the most accurate measurements in experiments.
Ionizing radiation
To better understand the operation of a Geiger-Muller counter, it is useful to have an understanding of ionizing radiation in general. By definition, these include what can cause ionization of a substance in its normal state. This requires a certain amount of energy. For example, radio waves or even ultraviolet light are not considered ionizing radiation. The border begins with "hard ultraviolet", aka "soft X-ray". This type is a photonic type of radiation. High energy photons are commonly called gamma quanta.
For the first time Ernst Rutherford divided ionizing radiation into three types. This was done on an experimental setup using a magnetic field in a vacuum. Subsequently it turned out that this:
α - nuclei of helium atoms
β - high energy electrons
γ - gamma quanta (photons)
Later, neutrons were discovered. Alpha particles are easily trapped even by ordinary paper, beta particles have a slightly higher penetrating power, and gamma rays have the highest. The most dangerous are neutrons (at a distance of up to many tens of meters in the air!). Due to their electrical neutrality, they do not interact with the electron shells of the substance molecules. But once in the atomic nucleus, the probability of which is high enough, lead to its instability and decay, with the formation, as a rule, of radioactive isotopes. And already those, in turn, decaying, themselves form the whole "bouquet" of ionizing radiation. The worst thing is that an irradiated object or living organism itself becomes a source of radiation for many hours and days.
Geiger-Muller counter device and principle of its operation
Gas-discharge Geiger-Muller counter, as a rule, is made in the form of a sealed tube, glass or metal, from which air is evacuated, and instead of it an inert gas (neon or argon or their mixture) is added under low pressure, with an admixture of halogens or alcohol. A thin wire is stretched along the tube axis, and a metal cylinder is located coaxially with it. Both the tube and the wire are electrodes: the tube is the cathode and the wire is the anode. A minus from a constant voltage source is connected to the cathode, and a plus from a constant voltage source is connected to the anode through a large constant resistance. Electrically, a voltage divider is obtained, at the midpoint of which (the junction of the resistance and the anode of the meter) the voltage is practically equal to the voltage at the source. This is usually a few hundred volts.
When an ionizing particle flies through the tube, atoms of an inert gas, already in an electric field of great strength, experience collisions with this particle. The energy given off by the particle during the collision is enough to detach electrons from the gas atoms. The resulting secondary electrons themselves are capable of forming new collisions and, thus, a whole avalanche of electrons and ions is obtained. Under the action of an electric field, electrons are accelerated towards the anode, and positively charged gas ions - towards the cathode of the tube. Thus, an electric current is generated. But since the energy of the particle has already been spent on collisions, in whole or in part (the particle flew through the tube), the supply of ionized gas atoms also ends, which is desirable and is provided by some additional measures, which we will talk about when analyzing the parameters of the counters.
When a charged particle enters the Geiger-Muller counter, due to the resulting current, the resistance of the tube drops, and with it the voltage at the midpoint of the voltage divider, which was discussed above. Then the resistance of the tube is restored due to the increase in its resistance, and the voltage again becomes the same. Thus, we get a negative voltage pulse. By counting the momenta, we can estimate the number of particles passing by. The electric field strength is especially high near the anode due to its small size, which makes the meter more sensitive.
Geiger-Muller counter designs
Modern Geiger-Müller counters are available in two basic versions: "classic" and flat. The classic counter is made of a thin-walled metal tube with corrugation. The corrugated surface of the meter makes the tube rigid, resistant to external atmospheric pressure and does not allow it to crumple under its influence. At the ends of the tube there are sealing insulators made of glass or thermosetting plastic. They also contain conclusions-caps for connecting to the instrument circuit. The tube is marked and covered with a durable insulating varnish, not counting, of course, its leads. The polarity of the terminals is also indicated. It is a versatile counter for all types of ionizing radiation, especially beta and gamma.
Counters sensitive to soft β-radiation are made differently. Due to the small range of β-particles, they have to be made flat, with a mica window, which weakly delays beta radiation, one of the options for such a counter is a radiation sensor BETA-2... All other properties of meters are determined by the materials from which they are made.
Counters designed for recording gamma radiation contain a cathode made of metals with a high charge number, or are coated with such metals. Gas is extremely poorly ionized by gamma photons. But on the other hand, gamma photons are capable of knocking out many secondary electrons from the cathode, if it is chosen in a suitable way. Geiger-Müller counters for beta particles are made with thin windows for better particle permeability, since they are ordinary electrons, just received a lot of energy. They interact with matter very well and quickly lose this energy.
In the case of alpha particles, the situation is even worse. So, despite the very decent energy, of the order of several MeV, alpha particles interact very strongly with molecules on the way, and quickly lose energy. If a substance is compared to a forest, and an electron to a bullet, then alpha particles will have to be compared to a tank breaking through a forest. However, an ordinary counter responds well to α-radiation, but only at a distance of up to several centimeters.
For an objective assessment of the level of ionizing radiation dosimeters meters for general use are often equipped with two parallel meters. One is more sensitive to α and β radiation, and the second to γ \u200b\u200brays. This scheme of using two counters is implemented in the dosimeter RADEX RD1008and in the dosimeter-radiometer RADEX MKS-1009 in which the counter is installed BETA-2 and BETA-2M... Sometimes a bar or plate made of an alloy containing an admixture of cadmium is placed between the counters. When neutrons hit such a bar, γ-radiation is generated, which is recorded. This is done to enable the determination of neutron radiation, to which simple Geiger counters are practically insensitive. Another way is to cover the body (cathode) with impurities capable of imparting sensitivity to neutrons.
Halogens (chlorine, bromine) are mixed with the gas for fast self-extinguishing of the discharge. Alcohol vapors serve the same purpose, although alcohol in this case is short-lived (this is generally a feature of alcohol) and the "sober" counter constantly starts "ringing", that is, it cannot work as intended. This happens sometime after the registration of 1e9 pulses (billion) which is not so much. Halogen meters are much more durable.
Parameters and operating modes of Geiger counters
Sensitivity of Geiger counters.
The counter sensitivity is estimated by the ratio of the number of micro-roentgen from the reference source to the number of pulses caused by this radiation. Since Geiger counters are not designed to measure the energy of particles, an accurate estimate is difficult. Counters are calibrated against exemplary isotope sources. It should be noted that this parameter may differ greatly for different types of counters, below are the parameters of the most common Geiger-Muller counters:
Geiger-Muller counter Beta 2 - 160 ÷ 240 imp / mkR
Geiger-Muller counter Beta 1 - 96 ÷ 144 imp / mkR
Geiger-Muller counter SBM-20 - 60 ÷ 75 imp / mkR
Geiger-Muller counter SBM-21 - 6.5 ÷ 9.5 imp / microR
Geiger-Muller counter SBM-10 - 9.6 ÷ 10.8 imp / microR
Entrance window area or work area
The area of \u200b\u200bthe radiation sensor through which radioactive particles fly. This characteristic is directly related to the dimensions of the sensor. The larger the area, the more particles will be captured by the Geiger-Muller counter. Usually this parameter is indicated in square centimeters.
Geiger-Muller counter Beta 2 - 13.8 cm 2
Geiger-Muller counter Beta 1 - 7 cm 2
This voltage corresponds to approximately the middle of the operating characteristic. The operating characteristic is the flat part of the voltage dependence of the number of recorded pulses, therefore it is also called a "plateau". At this point, the highest operating speed is reached (upper measurement limit). Typical value 400 V.
The width of the working characteristic of the counter.
This is the difference between the spark breakdown voltage and the voltage at the flat end of the characteristic. Typical value 100 V.
Counter slope.
The slope is measured as a percentage of pulses per volt. It characterizes the statistical measurement error (counting the number of pulses). Typical value 0.15%.
Permissible operating temperature of the meter.
For meters of general use -50 ... +70 degrees Celsius. This is a very important parameter if the counter works in chambers, channels, and other places of complex equipment: accelerators, reactors, etc.
Counter working resource.
The total number of pulses that the meter registers until the moment when its readings begin to become incorrect. For appliances with organic additives, self-extinguishing is usually 1e9 (ten to the ninth power, or one billion). The resource is counted only if the operating voltage is applied to the meter. If the counter is simply stored, this resource is not consumed.
Dead time counter.
This is the time (recovery time) during which the counter conducts current after being triggered by a passing particle. The existence of such a time means that there is an upper limit for the pulse frequency, and this limits the measurement range. Typical value 1e-4 s, that is, ten microseconds.
It should be noted that due to the dead time, the sensor can be "off scale" and be silent at the most dangerous moment (for example, a spontaneous chain reaction in production). There have been such cases, and lead screens are used to combat them, covering part of the sensors of alarm systems.
Own counter background.
Measured in thick-walled lead chambers to assess meter quality. Typical value is 1… 2 pulses per minute.
Practical application of Geiger counters
Soviet and now Russian industry produces many types of Geiger-Muller counters. Here are some common brands: STS-6, SBM-20, SI-1G, SI21G, SI22G, SI34G, "Gamma" series meters, end-face meters " Beta”And there are many others. All of them are used for monitoring and measuring radiation: at nuclear facilities, in scientific and educational institutions, in civil defense, medicine, and even everyday life. After the Chernobyl accident, household dosimeters, previously unknown to the population even by name, became very popular. There are many brands of household dosimeters. They all use the Geiger-Müller counter as a radiation sensor. In household dosimeters, one to two tubes or end meters are installed.
UNITS OF MEASUREMENT OF RADIATION VALUES
For a long time, the unit of measurement P (roentgen) was widespread. However, with the transition to the SI system, other units appear. X-ray is a unit of exposure dose, "amount of radiation", which is expressed by the number of formed ions in dry air. At a dose of 1 R in 1 cm3 of air, 2.082e9 ion pairs are formed (which corresponds to 1 unit of the CGSE charge). In the SI system, the exposure dose is expressed in coulombs per kilogram, and with X-rays this is related to the equation:
1 C / kg \u003d 3876 R
The absorbed dose of radiation is measured in joules per kilogram and is called Gray. This is in return for the outdated unit. The absorbed dose rate is measured in grays per second. The exposure dose rate (DER), previously measured in roentgens per second, is now measured in amperes per kilogram. The equivalent dose of radiation at which the absorbed dose is 1 Gy (gray) and the radiation quality factor is 1 is called Sievert. Rem (the biological equivalent of X-rays) is one hundredth of a sievert, and is now considered obsolete. Nevertheless, all obsolete units are very actively used today.
The main concepts in radiation measurements are dose and power. The dose is the number of elementary charges in the process of ionization of a substance, and the rate is the rate at which a dose is formed per unit of time. And in what units it is expressed is a matter of taste and convenience.
Even the smallest dose is dangerous in the sense of long-term consequences for the body. The hazard calculation is quite simple. For example, your dosimeter reads 300 milliroentgens per hour. If you stay in this place for a day, you will receive a dose of 24 * 0.3 \u003d 7.2 roentgens. This is dangerous and you need to get out of here as soon as possible. In general, having found even weak radiation, one must move away from it and check it even at a distance. If she “follows you”, you can be “congratulated”, you have been hit by neutrons. And not every dosimeter can react to them.
For radiation sources, a value is used that characterizes the number of decays per unit of time, it is called activity and is also measured in many different units: curie, becquerel, rutherford and some others. The amount of activity, measured twice with sufficient time spacing, if it decreases, allows you to calculate the time, according to the law of radioactive decay, when the source becomes sufficiently safe.
Household dosimeters made in Russia and other CIS countries occupy a leading position in the world market, so only such devices were chosen for the editorial test. They were tested in laboratory conditions (alpha, beta and gamma sources), as well as at one of the sites of radioactive contamination (radium-226, 0.92 μSv / h) and in domestic conditions (potash fertilizers, welding electrodes with the addition of thorium and ionization smoke detectors). For control, we used an Exploranium GR-130 gamma spectrometer. All dosimeters measured the level of gamma radiation (except for soft) within the passport error, and discrepancies for other types of radiation were significant. Most of the tested dosimeters use the classic Geiger-Muller counter SBM-20 manufactured by Elektrokhimpribor. Alas, its sensitivity is poor, and at low radiation levels, the counting takes several minutes. In dosimeters the size of a wristwatch, the SBM-21 counter is used, which is even less sensitive (about 10 times). More advanced dosimeters use end-face meters. In our test, we used a dosimeter with such a Beta-1 counter, manufactured by Consensus, which is approximately twice as sensitive to gamma radiation as SBM-20, but also more expensive.
Radex RD1503 +
Sensor: SBM-20 without filter. Measurements: Overestimates readings at low energies of gamma radiation and mixed gamma-beta radiation. On some sources, the device went off scale - the upper limit of the range is the smallest of all test participants. The natural background overestimates about one and a half times. It is poorly suited for searching small foci of infection due to the low sensitivity of the sensor. conclusions: the device has a user-friendly interface; The only disappointing thing is the frequent, unmotivated restart of the measurement cycle, which can delay obtaining accurate results.
Radex RD1706
Sensor: 2хСБМ-20 without filters. Measurements: Overestimates readings on soft gamma radiation and mixed gamma-beta radiation. Overestimates the natural background by about one and a half times. It is not ideal for searching for small foci of infection, but it is suitable: two sensors accelerate its response to changes in radiation levels. Conclusions: nice interface plus double measurement speed. In addition, this device is much less prone to unmotivated restart of measurements.
SOEKS-01M
Sensor: SBM-20 without filter. Measurements: Overestimates readings when exposed to soft gamma radiation and mixed gamma-beta radiation. Overestimates the natural background by about one and a half times. It is poorly suited for searching small foci of infection due to the low sensitivity of the sensor. Conclusions: very compact, lightweight, with a color display and the ability to connect to a computer via USB. The color palette and fonts do not always contribute to good readability. Displays a qualitative assessment of the background level and a graph of the reading over time. If the manufacturer updates the firmware, removing completely unnecessary startup and shutdown animations, optimizing colors and fonts for the best readability, you will get one of the best home appliances.
ISS-05 Terra-P
Sensor: SBM-20 with filter. Measurements: in general, the readings do not exceed the passport error. Thanks to the removable filter, Terra-P allows for approximate measurements of the flux density of hard beta radiation. The natural background is overestimated by about one and a half times. It is poorly suited for searching small foci of infection due to the low sensitivity of the sensor. conclusions: The device looks fit for field use, not just gentle home use. The filter contributes greatly to the accuracy and convenience of measurements. Unfortunately, the device does not remember the settings of the alarm threshold and resets it to 0.3 μSv / h.
Belwar RKS-107
Sensor: 2хСБМ-20 with filters. Measurements: very accurately measures radiation from cesium-137, but soft gamma radiation overestimates almost one and a half times. A separate mode for measuring the flux density of beta particles eliminates the use of any approximate conversion factors. Overestimates the natural background by about one and a half times. It is absolutely unsuitable for searching for foci of infection, since it does not know how to make measurements continuously and does not sound registration of particles. Conclusions:the harsh legacy of the Soviet past. This device does not know how to do anything except how to count the number of pulses in a certain time. The instruction without hesitation offers to carry out all mathematical processing to the user using a pencil and paper. On the other hand, this is a device registered in the registry that undergoes individual testing, but at the same time stands like a regular household dosimeter.
DP-5V
Sensor: SBM-20 for measuring high, medium and high radiation levels, SI3BG for measuring huge radiation levels. Equipped with filter and control source for strontium-90. Measurements: at less than 0.5 μSv / h, the pointer slowly oscillates, making measurement difficult. At high radiation levels, the instrument readings are quite stable over a wide range of gamma-ray energies. The low sensitivity of the sensor is partly compensated for by its placement on a retractable rod, so finding radiation spots with the DP-5 is easier than with most other test participants. Conclusions: military, and therefore even more severe legacy of the Soviet past. In some cases, such a device can be obtained for a symbolic price. But it's more of a collection item or props.
Polimaster DKG-RM1603A
Sensor: SBM-21 without filter. Measurements: the dosimeter overestimates soft gamma radiation by about two times. Not sensitive to beta radiation. Overestimates the natural level of radiation by about a quarter. Local contamination can only be detected by chance - the device reacts very slowly to changes in the radiation level. Conclusions: the inhibited response to changes in the dose rate is not very encouraging.
SNIIP Aunis MKS-01SA1M
Sensor: end counter Beta-1, sliding filter. Measurements: the only test participant who was able to adequately measure the flux density of beta particles from cesium-137 and measure the flux density of alpha particles. Overestimates the natural level of radiation by about one and a half times. Thanks to the sensor, which is the most sensitive to gamma and especially beta radiation, it is the most suitable instrument of all tested for finding radioactive spots. Conclusions: by far the best device. A very convenient system for indicating the relative statistical error with continuous refinement of the result.
This review provides a description of a simple and fairly sensitive dosimeter that records even insignificant beta and gamma radiation. A domestic type SBM-20 acts as a radiation sensor.
Outwardly, it looks like a metal cylinder with a diameter of 12 mm and a length of about 113 mm. Its operating voltage is 400 volts. A foreign sensor ZP1400, ZP1320 or ZP1310 can serve as an analogue.
Description of the dosimeter operation on the Geiger counter SBM-20
The dosimeter circuit is powered by only one 1.5 volt battery, since the current consumption does not exceed 10 mA. But since the operating voltage of the SBM-20 radiation sensor is 400 volts, a voltage converter is used in the circuit to increase the voltage from 1.5 volts to 400 volts. In this regard, extreme care should be taken when setting up and using the dosimeter!
The boost converter of the dosimeter is nothing more than a simple blocking generator. The emerging high voltage pulses on the secondary winding (terminals 5 - 6) of the Tr1 transformer are rectified by the VD2 diode. This diode must be high-frequency, since the pulses are short enough and have a high repetition rate.
If the Geiger counter SBM-20 is outside the radiation zone, there is no sound or light indication, since both transistors VT2 and VT3 are locked.
When beta or gamma particles hit the SBM-20 sensor, the gas inside the sensor is ionized, as a result of which a pulse is generated at the output, which is fed to the transistor amplifier and a click is heard in the BF1 telephone capsule and the HL1 LED flashes.
Outside the zone of intense radiation, LED flashes and clicks from the telephone capsule follow every 1 ... 2 seconds. This indicates a normal, natural background radiation.
When the dosimeter approaches any object with strong radiation (the scale of an aircraft instrument during the war or the luminous dial of an old watch), the clicks will become more frequent and may even merge into one continuous crack, the HL1 LED will be constantly on.
The dosimeter is also equipped with a pointer indicator - a microammeter. A trimmer resistor is used to adjust the sensitivity of the reading.
Dosimeter details
The transformer of the Tr1 converter is made on an armored core having a diameter of approximately 25 mm. Windings 1-2 and 3-4 are wound with a copper enameled wire with a diameter of 0.25 mm and contain respectively 45 and 15 turns. The secondary winding 5-6 is wound with a copper wire with a diameter of 0.1 mm, contains 550 turns.
The LED can be supplied by AL341, AL307. In the role of VD2, it is possible to use two KD104A diodes by connecting them in series. Diode KD226 can be changed to KD105V. Transistor VT1 can be changed to KT630 \u200b\u200bwith any letter, to KT342A. The telephone capsule must be selected with an acoustic coil impedance greater than 50 ohms. Microammeter with a total deflection current of 50 μA.
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In Ukraine, there is an established delivery system to the following cities: Kiev, Kharkov, Dnipro (Dnepropetrovsk), Odessa, Donetsk, Lviv, Zaporozhye, Nikolaev, Lugansk, Vinnitsa, Simferopol, Kherson, Poltava, Chernigov, Cherkassy, \u200b\u200bSumy, Zhitomir, Kirovograd, Khmelnitsky , Exactly, Chernivtsi, Ternopil, Ivano-Frankivsk, Lutsk, Uzhgorod and other cities of Ukraine.
In Belarus, there is an established delivery system to the following cities: Minsk, Vitebsk, Mogilev, Gomel, Mozyr, Brest, Lida, Pinsk, Orsha, Polotsk, Grodno, Zhodino, Molodechno and other cities of the Republic of Belarus.
In Kazakhstan, there is an established delivery system to the following cities: Astana, Almaty, Ekibastuz, Pavlodar, Aktobe, Karaganda, Uralsk, Aktau, Atyrau, Arkalyk, Balkhash, Zhezkazgan, Kokshetau, Kostanay, Taraz, Shymkent, Kyzylorda, Lisakovsk, Shakhtin Rider, Rudny, Semey, Taldykorgan, Temirtau, Ust-Kamenogorsk and other cities of the Republic of Kazakhstan.
The manufacturer TM "Infrakar" is a manufacturer of multifunctional devices such as a gas analyzer and opacimeter.
If the technical description does not contain the information you need about the device on the website, you can always contact us for help. Our qualified managers will clarify for you the technical characteristics of the device from its technical documentation: operating instructions, passport, form, operating instructions, diagrams. If necessary, we will take photos of the device, stand or device you are interested in.
You can leave feedback on the device, meter, device, indicator or product purchased from us. Your review, with your consent, will be published on the site without specifying contact information.
The description of the devices is taken from the technical documentation or from the technical literature. Most of the photos of the products were taken directly by our specialists before shipment. In the description of the device, the main technical characteristics of the devices are provided: nominal, measuring range, accuracy class, scale, supply voltage, dimensions (size), weight. If on the site you see a discrepancy between the name of the device (model) and the technical characteristics, photos or attached documents - let us know - you will receive a useful gift along with the purchased device.
If necessary, you can check the total weight and dimensions or the size of a separate part of the meter in our service center. If necessary, our engineers will help you choose a complete analog or the most suitable replacement for the device you are interested in. All analogs and replacements will be tested in one of our laboratories for full compliance with your requirements.
Our company carries out repair and maintenance of measuring equipment in more than 75 different factories of manufacturers of the former USSR and the CIS. We also carry out such metrological procedures: calibration, calibration, calibration, testing of measuring equipment.
Instruments are supplied to the following countries: Azerbaijan (Baku), Armenia (Yerevan), Kyrgyzstan (Bishkek), Moldova (Chisinau), Tajikistan (Dushanbe), Turkmenistan (Ashgabat), Uzbekistan (Tashkent), Lithuania (Vilnius), Latvia (Riga ), Estonia (Tallinn), Georgia (Tbilisi).
LLC "Zapadpribor" is a huge selection of measuring equipment at the best price-quality ratio. So that you can buy devices inexpensively, we monitor the prices of competitors and are always ready to offer a lower price. We only sell quality products at the best prices. On our site you can buy cheaply both the latest novelties and time-tested devices from the best manufacturers.
On the site there is a permanent action "Buy at the best price" - if on another Internet resource the product presented on our site has a lower price, then we will sell it to you even cheaper! Customers are also given an additional discount for feedback or photos of our products.
The price list does not indicate the entire range of products offered. You can find out the prices for goods that are not included in the price list by contacting the managers. Also from our managers you can get detailed information on how to buy cheap and profitable measuring devices wholesale and retail. Phone and e-mail for advice on purchase, delivery or discount are given above the product description. We have the most qualified employees, high-quality equipment and a favorable price.
LLC "Zapadpribor" is an official dealer of manufacturers of measuring equipment. Our goal is to sell high quality products with the best price offers and service to our customers. Our company can not only sell the device you need, but also offer additional services for its verification, repair and installation. To ensure you have a pleasant experience after purchasing on our website, we have provided special guaranteed gifts for the most popular products.
The META plant is a manufacturer of the most reliable instruments for technical inspection. The STM brake tester is produced at this plant.
If you can repair the device yourself, then our engineers can provide you with a full set of necessary technical documentation: electrical circuit, TO, RE, FO, PS. We also have an extensive database of technical and metrological documents: technical specifications (TU), terms of reference (TZ), GOST, industry standard (OST), verification methodology, certification methodology, verification diagram for more than 3500 types of measuring equipment from the manufacturer of this equipment. From the site you can download all the necessary software (program, driver) necessary for the operation of the purchased device.
We also have a library of regulatory documents that are related to our field of activity: law, code, decree, decree, temporary regulation.
At the request of the customer, verification or metrological certification is provided for each measuring device. Our employees can represent your interests in such metrological organizations as Rostest (Rosstandart), Gosstandart, Gospotrebstandart, TsLIT, OGMetr.
Sometimes customers may enter the name of our company incorrectly - for example, zapadprybor, zapadprylad, zapadpribor, zapadprylad, zakhidpribor, zakhidpribor, zakhidpribor, zakhidprylad, zakhidpribor, zakhidprylad, zakhidprylad That's right - zapadpribor.
LLC "Zapadpribor" is a supplier of ammeters, voltmeters, wattmeters, frequency meters, phase meters, shunts and other devices of such manufacturers of measuring equipment as: PO "Electrotochpribor" (М2044, М2051), Omsk; OJSC "Instrument-making plant" Vibrator "(М1611, Ц1611), St. Petersburg; OJSC Krasnodarskiy ZIP (E365, E377, E378), OOO ZIP-Partner (Ts301, Ts302, Ts300) and OOO ZIP Yurimov (M381, Ts33), Krasnodar; JSC "VZEP" ("Vitebsk plant of electrical measuring instruments") (E8030, E8021), Vitebsk; JSC "Electropribor" (М42300, М42301, М42303, М42304, М42305, М42306), Cheboksary; Electroizmeritel JSC (Ts4342, Ts4352, Ts4353), Zhitomir; PJSC "Uman plant" Megommeter "(F4102, F4103, F4104, M4100), Uman.