First steps in radio, many often begin with independent fabrication of a transistor radio. Along the way, introduces the electronic components, acquired the skills in installation and work with measuring devices. And achieve rapid practical results is to the same positive stimulus for further study of fundamentals of electronics, gives confidence in their abilities and capabilities.SIMPLE RECEIVERS ON TRANSISTORS
First steps in radio, many often begin with independent fabrication of a transistor radio. Along the way, introduces the electronic components, acquired the skills in installation and work with measuring devices. And achieve rapid practical results is to the same positive stimulus for further study of fundamentals of electronics, gives confidence in their abilities and capabilities.
Electronic devices based on microprocessors and integrated circuits are less sensitive to the parameters of the supply voltage. To ensure the safe operation of these devices use voltage regulators with protection. In many power supplies is reduced to cut power to the circuit if a short circuit in it or a sudden increase in load current. Such, for example, the popular voltage stabilizers КР142ЕН5. 
As you know, speaker of the personal computer (PC) it is necessary to include separately. If they are installed at some distance from the operator, this situation is hardly comfortable, especially if the user wishes to view on a DVD movie recorder or any other video, accompanied by sound effects.
There are many games in which, for example, the number of points scored by the player. is determined by throwing dice. It is easy to make and the electronic “dice” random number generator. Schemes of such generators and descriptions found in Amateur radio literature.
Perhaps in the near future when the new spacecraft will go to the moon, Venus or Mars in the Arsenal of the astronauts will be robots who will come first to the planet’s surface to conduct scientific researches, to perform simple welding and Assembly work. So I decided the guys from the mug space simulation Sumy city station of young technicians and build a similar robot with their hands.
Compression, and adsorption refrigerators often fail due to the fact that they denied Electromechanical relays or breakers on the basis of the bimetallic plates. The first of them is used to trigger synchronous electric motors, serving a compression refrigerator system, and the second are the basis of the tracking systems and maintain at a predetermined temperature level freezer [1]. The reason for failure and the other is a burnout or a mechanical failure of the spring contacts in these devices. Ego especially applies to older models of refrigerators. And often you can see that, because of the insignificant, but hard to handle breakdowns (due to the lack of spare equipment) the throw is still quite usable machines. In the material made the attempt to remove such faults in household appliances.
Two LEDs with different color (e.g., red and green), you can build a simple indicator for voltages from 4.5 to 220 V. It is also able to determine the polarity of the source in the range 8-220 V. When measuring AC voltage, both diode glow, but if it is constant — lights one of them depending on the wiring polarity indicator. The scheme proposed by the Czechoslovak journal “Amaterske Radio”.
The well-known school electroscope, which demonstrate the phenomena of electrostatics, determines only the presence of electrostatic charge. What is it, positive or negative, we can only guess. This shortage is deprived of the device designed for young hams syut Nadvirna town, Ivano-Frankivsk region. It not only determines the sign of the charge, but also its approximate size.
Our magazine has already told about this exciting game, made on the electromagnetic relay (see “M-K” №1, 1976). And today hams instead of contact devices are widely used in their structures with modern elements as transistors, thyristors, LEDs, integrated circuits. New versions of the game “Who is faster?” with the use of such devices and readers.
Instead of bulky and uncomfortable electrostatic machines Wimshurst, coils Ruhmkorff in high school physics classrooms are increasingly high voltage converters voltage. They can be used to Pro* led experiments in such branches of physics as electrostatics and current in gases. We offer our readers “e-stick” — one of those devices.