Homemade detectors. Encyclopedia of radio electronics and electrical engineering

Encyclopedia of radio electronics and electrical engineering / Beginner radio amateur

 Comments on the article

If it is not possible to purchase a ready-made detector, you can make the detector yourself.

One of the designs of a homemade detector is shown in Fig. one.

Rice. 1. The design of a homemade galenic detector

The base of the detector is a block 35 mm long, 15 mm wide and 3-5 mm thick. They drank it from a durable insulating material - ebonite, textolite, fiber or dry plywood. The corners of the block were rounded with a file. Drilled two holes in it for the legs from the plug. The distance between the centers of the holes should be 20 mm. To one leg under the nut, attach a cup, twisted from copper wire 1-1,5 mm thick. In this cup firmly insert a crystal of galen (lead luster), wrapped in foil.

Make a lever from two strips cut out of any metal with a thickness of 1-1,5 mm. Bend the lever stand at the bottom at a right angle. Drill a hole through which the stand is attached to the contact leg under the nut. Fasten both parts of the lever with a bolt. Sharpen the end of the lever, on which the wooden handle is put on, so that the handle does not crack when put on it and holds well.

A spiral can be twisted from a balalaika or guitar string on a nail. The end of the spiral in contact with the crystal must be very sharp. We recommend flattening it with a hammer and cutting it obliquely with scissors.

The lever should move up and down freely and at the same time be held in position. In this case, the spiral should only lightly touch the surface of the crystal.

Such a detector does not work for any position of the tip of the spiral on the crystal. On the surface of the crystal there are so-called sensitive points - places where a barrier layer is formed when the tip comes into contact with them.

To find a sensitive point, the tip of the spiral must be rearranged on the crystal from place to place, raising and lowering the lever. This is a very painstaking business: you just have to push the receiver a little, the tip goes astray from the sensitive point and you need to look for it again.

A crystal of lead luster - galen can be made by yourself. This will require pure lead, powdered sulfur (the so-called gray color) and a glass test tube.

A piece of lead was scraped off with a knife or drunk with a large file. Mix the resulting sawdust with sulfur. The approximate proportion of lead and sulfur should be as follows: lead filings 20-30 g, sulfur 5-8 g. If there are no scales, you can mix portions equal in volume, for example, one thimble of lead filings and the same amount of sulfur. Pour the mixture into a test tube, and lightly tamp with a wooden stick. Attach a wire handle to the test tube so that you do not burn your fingers when heating the test tube (Fig. 2).

Rice. 2. A test tube with a mixture of sulfur and lead filings is heated over a fire

Heat the test tube with the mixture on the fire of an alcohol lamp, kerosene stove or primus stove (this must be done in the air or in some non-residential premises). First, hold the test tube high above the flame, and then, when the sulfur melts, bring the test tube closer to the fire. When the mixture heats up, remove the test tube from the heat and, holding it in an upright position, let it cool down gradually. The crystal can be obtained only by breaking the test tube.

The resulting mass is similar to slag. In places of fracture, it has a shiny granular surface. Such a crystal surface has good detecting properties. In the detector, it should be facing the tip of the steel spring.

I must say that the first time it is not always possible to get a crystal of good quality. If the test tube is heated over high heat, it may burst and the mixture of lead and sulfur will burn. If you fail, do not despair, but repeat the experience again.

If lead and sulfur are not available, a graphite detector can be made. Its device is shown in Fig. 3. It detects contact between graphite from a hard (T grade) simple (non-chemical) pencil 20-25 mm long and a piece of a steel, non-rusted blade from a safety razor.

Rice. 3. Graphite detector

The insulating block and contact legs are exactly the same as in the design of the galenic detector. A piece of a safety razor blade is clamped under the nut of the contact leg. Under the nut of the second contact leg, the end of the copper wire is pressed, the other end of which is wrapped 3-4 times around the graphite rod. The sharply sharpened end of the graphite is in contact with the surface of the blade. The length of the wire loop holding the graphite rod must be sufficient so that the graphite tip can be moved over the entire surface of the blade and thereby find the most sensitive point of the detector.

The graphite detector works quite satisfactorily. Its disadvantage is the low stability of the sensitive point and the need for frequent sharpening of the graphite tip.

You can try to make a detector with a constant sensitive point. Its structure (in a greatly enlarged form) is shown in Fig. 4.

Rice. 4. Homemade detector with a constant sensitive point

Take a piece of copper wire 2,5-3 mm thick and 20-30 mm long. Clean it to a shine with fine sandpaper, heat it red-hot on a spirit lamp, gas burner or primus stove and quickly dip it in ammonia. A thin layer of oxide forms on the wire. It is a semiconductor. Carefully clean one end of the wire from the oxide layer and screw a piece of copper wire to it. To the other end of the oxidized wire, without stripping it, screw a piece of unoxidized copper wire. The free ends of these conductors will serve as detector leads. Making a good detector the first time is not always possible. Therefore, we advise you to make several such detectors and select from them the one that will give the best results.

Author: V.Borisov

See other articles Section Beginner radio amateur.

Read and write useful comments on this article.

<< Back

Latest news of science and technology, new electronics:

Traffic noise delays the growth of chicks 06.05.2024

The sounds that surround us in modern cities are becoming increasingly piercing. However, few people think about how this noise affects the animal world, especially such delicate creatures as chicks that have not yet hatched from their eggs. Recent research is shedding light on this issue, indicating serious consequences for their development and survival. Scientists have found that exposure of zebra diamondback chicks to traffic noise can cause serious disruption to their development. Experiments have shown that noise pollution can significantly delay their hatching, and those chicks that do emerge face a number of health-promoting problems. The researchers also found that the negative effects of noise pollution extend into the adult birds. Reduced chances of reproduction and decreased fertility indicate the long-term effects that traffic noise has on wildlife. The study results highlight the need ... >>

Wireless speaker Samsung Music Frame HW-LS60D 06.05.2024

In the world of modern audio technology, manufacturers strive not only for impeccable sound quality, but also for combining functionality with aesthetics. One of the latest innovative steps in this direction is the new Samsung Music Frame HW-LS60D wireless speaker system, presented at the 2024 World of Samsung event. The Samsung HW-LS60D is more than just a speaker system, it's the art of frame-style sound. The combination of a 6-speaker system with Dolby Atmos support and a stylish photo frame design makes this product the perfect addition to any interior. The new Samsung Music Frame features advanced technologies including Adaptive Audio that delivers clear dialogue at any volume level, and automatic room optimization for rich audio reproduction. With support for Spotify, Tidal Hi-Fi and Bluetooth 5.2 connections, as well as smart assistant integration, this speaker is ready to satisfy your ... >>

A New Way to Control and Manipulate Optical Signals 05.05.2024

The modern world of science and technology is developing rapidly, and every day new methods and technologies appear that open up new prospects for us in various fields. One such innovation is the development by German scientists of a new way to control optical signals, which could lead to significant progress in the field of photonics. Recent research has allowed German scientists to create a tunable waveplate inside a fused silica waveguide. This method, based on the use of a liquid crystal layer, allows one to effectively change the polarization of light passing through a waveguide. This technological breakthrough opens up new prospects for the development of compact and efficient photonic devices capable of processing large volumes of data. The electro-optical control of polarization provided by the new method could provide the basis for a new class of integrated photonic devices. This opens up great opportunities for ... >>

Random news from the Archive One injection will relieve nicotine addiction 18.03.2016 Quitting smoking is not an easy task, but now scientists have created an anti-nicotine vaccine, which in the future can help a person get rid of this habit in just one shot. Why is it so difficult to quit smoking? It's all about nicotine, which is highly addictive, and a new vaccine could help a smoker's body attack nicotine molecules before they reach the brain, thereby removing their effect along with the person's urge to smoke. The anti-nicotine vaccine idea is not new. For the first time they started talking about it a couple of years ago, but then it worked only on 30% of the subjects. Now researchers have improved it by changing the molecules that alert the immune system and thus make it attack nicotine. With the right concentration of carrier proteins and nicotine molecules, the mice developed an active antibody response, meaning the vaccine worked. In addition, when given a second dose of nicotine, vaccinated mice had an extremely reduced and blunted response to this chemical. In future studies, the scientists plan to study the physical dynamics between different vaccine molecules and the immune system to determine the concentration of antibodies needed for the vaccine to work properly. While the anti-nicotine vaccine is not yet commercially available, studies show that it can be extremely effective. Moreover, a similar technique could be used to treat other addictions, for example, the same researchers are working on an anti-opioid drug right now. It is worth recalling how smoking can affect not only your body, but also your genes.

Other interesting news:

▪ Hearing aid for ornithologist

▪ Electric scooter NIU Gova C0

▪ Eco-fueled catamaran sails around the world

▪ Philips Hue Secure series cameras and sensors

▪ Freescale expands range of automotive microcontrollers

News feed of science and technology, new electronics

Interesting materials of the Free Technical Library:

▪ section of the site The most important scientific discoveries. Article selection

▪ article Prescribe Izhitsu. Popular expression

▪ article How to determine the age of a tree? Detailed answer

▪ article The functional composition of Daewoo TVs. Directory

▪ article Internal lightning protection system. Encyclopedia of radio electronics and electrical engineering

▪ article Low-noise antenna amplifier in the 430 MHz band. Encyclopedia of radio electronics and electrical engineering

Leave your comment on this article:

All languages ​​of this page

Arabic	Hebrew	Polish
Bengali	Hindi	Portuguese
Chinese	Italian	Spanish
English	Japanese	Turkish
French	Korean	Ukrainian
German	Malay	Vietnamese

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

www.diagram.com.ua
2000-2024