Petrosani Hobby Magazine - no5 - 2005

Petrosani Hobby Magazine - no. 5 - 2005 - How do we build the coils?

Reading time: 3 minute

Author: Petrosani Children's Club
Quarterly magazine of the circle of electronic constructions and amateur radio
Coordinator: Prof. Kovacs Imre - YO2LTF

Did you know that ...? Do the nerves in your body work on the basis of electrical impulses? And the electrical signals from the brain set the muscles in motion, transmitting information from the eyes, ears, nose, tongue and skin back to the brain?

The structure of the magazine

1. Dear colleagues from Petrosani

I read with great interest your magazine which is very interesting, at our level of students, which also emerges from the editorial staff, a very young team, students like us.

The articles are in our field, at our level, which makes us very happy. We really like what you publish in the magazine. The articles are very interesting and full of practical ideas.

My name is Marius Vasii, I have the indicator YO5-028 / CJ, student at Somes School Group. I have been attending the Dej Children's Club radio broadcasting circle for three years. Here I learned the first notions of electronics that presented emigmas for me. We have made many installations such as: optical, acoustic signals, generators and amplifiers…

2. Coil construction

  • Conductive materials used in the construction of coils;
  • High frequency coils (radio frequency);
  • Low frequency coils.

3. Equivalence table

  • CIS transistors type KT - silicon;

4. Metal detectors

The first such metal detectors appeared many years ago. We remember from childhood the war movies in which the soldiers searched with such detectors for the metal mines hidden on the front. The military technique once developed was "transferred" to civilian life. Besides other more "domestic" applications, metal detectors for treasure hunters had a big word, most of us read as children about the legends of our ancestors, about their treasures hidden in various places.

The mirage of these treasures has reached a large mass of people who have made or bought devices of this kind more and more sophisticated. The young electronics engineer is tempted by all this and if he manages to build such a device, it will be a gain anyway. Their complexity, the large number of components used, their variants, will help him to deepen the basic principles of practical electronics. We will thus become familiar with power supplies, with operational amplifiers, with oscillators, with technical principles such as PLL, UCO, BFO...

5. Radio-TV troubleshooting

  • Debugging stages;
  • Never look;
  • Mandatory steps;
  • Checking components;
  • Practical recommendations, advice;

Over the years, RTv's troubleshooting has been a permanent challenge for young electronics engineers. Pupils, students or engineers, they had made a real hobby to outdo them in solving defects in electronic equipment.

With the passing of the years, this passion has decreased in intensity, but even today there are many young people who, being passionate, surpass themselves. Troubleshooting is and will be a challenge for anyone who thinks they are electronics…

6. Black and white TV power supply

The power supply includes:

  • mains switch;
  • the U601 filter that protects the network against high frequency radiation from the TV;
  • rectifier tip;
  • filter capacitor C607.

The switching stabilizer, with direct energy transfer, which consists of:

  • T601 series regulating transistor type BUX84;
  • error amplifier equipped with T603 type BF297;
  • Zener D606 diode type DZ5V1;
  • the control stage of the transistor, equipped with type T602 BC252B and diode D605 type BA157;
  • Zener diode D607 type PL180Z.

The voltages required to supply the component floors of the TV are obtained from two independent sources:

  • 220Vac / 50Hz alternating current network;
  • final floor lines.

7. Curiosities

The space that a body occupies is called volume. The amount of material in that space is called its mass. In the metric system, the volume is measured in cubic meters (m) or in liters (l).

The mass of a liter of water is one kilogram. Weight is measured in grams (g) and kilograms (kg). The weight is different from the weight.

And many other curiosities.

8. Transforming the TV into a monitor

Sometimes we have to use a TV as a monitor. The reasons are many, whether our monitor just broke, or we have guests and we can not see the last movie received, all in the group.

The scheme is not complicated at all, it uses an integrated circuit of the type 74LS86, two transistors type BC547, some resistors and capacitors. The printed wiring is also presented in the article. Two plugs are also required, one type SCART (dad) and a plug in a faulty monitor.


If you want to collaborate with this magazine, please access the contact section on the last page of each publication.


  1. And at what "voltage" do these electrical impulses rise, not the other way around, but do I think about charging my phone when I'm nervous ?! Attention, it is a question without other connotations!

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