Polymer film thickness gauge. Scheme, description

Free technical library

ENCYCLOPEDIA OF RADIO ELECTRONICS AND ELECTRICAL ENGINEERING
Free library / Schemes of radio-electronic and electrical devices

Polymer film thickness gauge. Encyclopedia of radio electronics and electrical engineering

Free technical library

Encyclopedia of radio electronics and electrical engineering / Home, household, hobby

Comments on the article

After reading the article by A. Velsky "Assessment of the thickness of the paintwork" ("Radio", 2002, No. 2, p. 57), I decided to use the simple device described in it to control the thickness of the polymer film. However, it turned out that for this purpose its accuracy is insufficient, the reference scale is non-linear, and its length is far from being fully used. These features are also noted by the author of this article.

As a result of the improvement of the meter, the circuit shown in the figure appeared. The device assembled on it measures the thickness of any dielectric films, including paint coatings, in the range of 0,05 ... 1 mm with an error of no more than 5%.

(click to enlarge)

The generator on the transistor VT1 through the transformer T1 supplies alternating current with a frequency of approximately 1000 Hz to the measuring bridge L1L2R3R7. Coil L1 with an open magnetic circuit - a sensor. If the ends of its magnetic circuit are tightly pressed against the smooth surface of a mild steel plate, the inductance of the sensor is maximum and equal to the inductance of the exemplary coil L2. The exact balance of the bridge is achieved with a tuning resistor R3. If a dielectric film is placed between the ends of the magnetic circuit of the sensor and the plate, the bridge will be unbalanced and an alternating voltage with an amplitude proportional to the thickness of the film will appear at the input of the two-stage amplifier on transistors VT2 and VT3. The amplified signal, rectified by diodes VD1 and VD2 (capacitor C8 - smoothing), is fed to the input of a DC amplifier on a transistor VT4, to the collector of which a microammeter RA17 is connected through a resistor R1. The second output of the microammeter is connected through the SB1 button to the collector of the transistor VT5 (directly or through the resistor R19, depending on the selected measurement subrange).

With a balanced measuring bridge, the pointer of the PA1 microammeter is set to zero with a variable resistor R18. Due to the fact that the cascades on transistors VT4 and VT5 are identical, a change in the ambient temperature does not cause a noticeable "departure" of the arrow and does not introduce errors into the measurement result. With the SA1 switch closed, the maximum measurable thickness is 0,2 mm, with the SA1 switch open, XNUMX mm.

The device is powered by a voltage of 12 V from any stabilized source. I used the power supply of the TV antenna amplifier. You can also use a battery of galvanic cells. A voltage of 7 ... 8 V is quite enough, so the Krona or Korund batteries are suitable. In this case, it is recommended to install a button with two groups of contacts as SB1. The second group, connected in series to the battery circuit, will serve as a power switch, which will protect the battery from discharging in between measurements.

I mounted the device in the case of the Ts43101 avometer, leaving the "native" microammeter in it. Transformer T1 - output from the transistor receiver "Russia-301". Its high-resistance winding is included in the collector circuit of transistor VT1. Coils L1 and 12 are TA-56 telephone capsules with covers and membranes removed.

I placed a measuring "table" made of 3 mm thick steel sheet with smooth and corrosion-free top and bottom surfaces on the top panel of the instrument. From below, inside the case, I pressed the L2 coil (exemplary) to the table with a tin clamp. I install the L1 coil (sensor) on the table from above, placing a measured film under it, and when checking zero - without a film. To get a countdown, I press the SB1 button. This is not recommended when the sensor is not on the stage. The arrow of the microammeter, sharply deviating, can hit the stop and bend.

Having assembled and turned on the device, first of all, check with an oscilloscope the presence of an alternating voltage on the winding II of the transformer T1. Press the L1 coil tightly against the surface of the measuring table and with the trimming resistor R3 achieve the minimum readings of the high-resistance voltmeter connected to the terminals of the capacitor C8. Then, turning off the voltmeter and pressing the SB1 button, set the pointer of the PA18 microammeter to zero with a variable resistor R1. Graduate the instrument scale by placing film samples of known thickness under the pickup coil. The required measurement limits are achieved by a selection of resistors R17 and R19.

Author: V.Naryzhny, Bataysk, Rostov region.

See other articles Section Home, household, hobby.

Read and write useful comments on this article.

<< Back

Latest news of science and technology, new electronics:

Machine for thinning flowers in gardens 02.05.2024

In modern agriculture, technological progress is developing aimed at increasing the efficiency of plant care processes. The innovative Florix flower thinning machine was presented in Italy, designed to optimize the harvesting stage. This tool is equipped with mobile arms, allowing it to be easily adapted to the needs of the garden. The operator can adjust the speed of the thin wires by controlling them from the tractor cab using a joystick. This approach significantly increases the efficiency of the flower thinning process, providing the possibility of individual adjustment to the specific conditions of the garden, as well as the variety and type of fruit grown in it. After testing the Florix machine for two years on various types of fruit, the results were very encouraging. Farmers such as Filiberto Montanari, who has used a Florix machine for several years, have reported a significant reduction in the time and labor required to thin flowers. ... >>

Advanced Infrared Microscope 02.05.2024

Microscopes play an important role in scientific research, allowing scientists to delve into structures and processes invisible to the eye. However, various microscopy methods have their limitations, and among them was the limitation of resolution when using the infrared range. But the latest achievements of Japanese researchers from the University of Tokyo open up new prospects for studying the microworld. Scientists from the University of Tokyo have unveiled a new microscope that will revolutionize the capabilities of infrared microscopy. This advanced instrument allows you to see the internal structures of living bacteria with amazing clarity on the nanometer scale. Typically, mid-infrared microscopes are limited by low resolution, but the latest development from Japanese researchers overcomes these limitations. According to scientists, the developed microscope allows creating images with a resolution of up to 120 nanometers, which is 30 times higher than the resolution of traditional microscopes. ... >>

Air trap for insects 01.05.2024

Agriculture is one of the key sectors of the economy, and pest control is an integral part of this process. A team of scientists from the Indian Council of Agricultural Research-Central Potato Research Institute (ICAR-CPRI), Shimla, has come up with an innovative solution to this problem - a wind-powered insect air trap. This device addresses the shortcomings of traditional pest control methods by providing real-time insect population data. The trap is powered entirely by wind energy, making it an environmentally friendly solution that requires no power. Its unique design allows monitoring of both harmful and beneficial insects, providing a complete overview of the population in any agricultural area. “By assessing target pests at the right time, we can take necessary measures to control both pests and diseases,” says Kapil ... >>

Random news from the Archive

New stable form of plutonium discovered 31.10.2019

A team of researchers from the HZDR Institute (Helmholtz Zentrum Dresden-Rossendorf), Germany, has discovered a completely new stable form of plutonium quite by accident. This unstable and radioactive element needs special measures during transportation, storage and disposal, and the discovery of German scientists can become a new way to solve the problems mentioned above.

The instability of plutonium makes it an incredibly powerful source of energy, on the one hand, and, on the other hand, a potentially destructive force capable of causing an ecological catastrophe. Some of the isotopes of plutonium can exist for tens of millions of years, and it is easy to imagine the consequences of contamination of groundwater, for example, with such isotopes. Therefore, scientists are constantly looking for new ways to more safely store, transport and dispose of plutonium and its compounds. And just during such studies, scientists from HZDR accidentally found a new stable form.

One of the safest forms of plutonium is plutonium dioxide, which is a ceramic material that does not dissolve in water and has a fairly high melting point. Plutonium dioxide nanoparticles can be obtained in different ways using various starting materials, called precursors (precursors), containing plutonium isotopes. German scientists in their experiments used precursors called Plutonium (VI) (Pu (VI)), dissolved in water, and noticed very strange chemical reactions.

Pu(VI), during its transformation into plutonium dioxide, passed through a transition phase in which this material became solid and stable. Under normal conditions, pentavalent plutonium Pu (V) is neither a solid nor a stable material, so what scientists managed to notice was attributed to the wrong course of chemical reactions for the synthesis of plutonium dioxide.

In order to confirm some of the assumptions, the researchers used the Rossendorf Beamline X-ray spectrometer (ROBL). This device allows you to measure the energy of radioactive elements by irradiating them with X-rays and measuring the intensity of their fluorescence. These studies confirmed the existence of a new phase of Pu(V), and the selected samples were re-tested after three months, which made it possible to confirm the stability of the new form of plutonium for a long time.

Other interesting news:

▪ Tiny electric car Rimono

▪ Classical music will help you pass the exam

▪ Microsoft buys Skype

▪ VHS continues to lose ground

▪ The use of puppets in medicine

News feed of science and technology, new electronics

Interesting materials of the Free Technical Library:

▪ section of the website Basics of First Medical Aid (BFA). Selection of articles

▪ article Gird the loins. Popular expression

▪ article The name of which capital means simply the capital? Detailed answer

▪ article How to give an enema. Health care

▪ article 4-channel microprocessor timer, thermostat, clock for the Smart Home system. Encyclopedia of radio electronics and electrical engineering

▪ article Controlling a DC electric motor. Encyclopedia of radio electronics and electrical engineering

Leave your comment on this article:

All languages of this page

Home page | Library | Articles | Website map | Site Reviews