When I needed a megaphone, I became acquainted with the prices of Chinese industrial products: as it turned out, they cost from 1500 to 8000 rubles., and found that such a device can collect a couple of hours with her hands. A megaphone (or loud speaker), an electrical circuit which recommend and bring forth, be useful for sports, in advertising, in conditions of constant excessive noise, playing games with the child and even in the minibus for broadcasting information to passengers in the rear seats.
STRENGTHEN THE VOICE OF THEIR HANDS
The quality of cement is usually determined by destruction of the samples. Moreover, this process lasts from seven to twenty-eight days. To speed it up decided young technicians of the radio circle of the pioneer city of Iskitim of the Novosibirsk region. “The task we were given in Vries cement plant — said the group members Zaitsev. — Together with the guys we have designed and built an instrument (Fig. 1), which brand of cement you can determine almost instantly”.
In recent years in our country and abroad is rapidly developing a new kind of consumer electronics device for home games. The name given to a special prefix to the TV, allowing you to create on the screen the imitation of various sports, military, and other games. These devices are built on the basis of the so-called telegraphic circuits or large integrated circuits.
For portable electronic equipment need a small volume and weight of the power supply. To solve this problem relatively simply by replacing passive LC and active RC filters.
Smoothly change the brightness of room lighting or hall comfortable with the thyristor voltage regulator (see Fig.). The scheme allows you to adjust the load voltage ranging from 220 V to 0, 25 W to 1 kW. But if the thyristors to supply the radiators, then it will increase to 1.5 kW. The main elements of the regulator, the thyristors V1, V2, included a counter each other and parallel to the load. They alternately pass current in one or in the other direction.
In many cities on the lively streets and highways have electronic thermometers. Some of them, with light of a mercury column, like an ordinary thermometer, the other made in the form of a digital display. To make such devices themselves is not available to everyone. But the simplified design of the indicator can be manufactured by the forces of the circle of automation students.
Many families today live in multi-storey buildings and use of household washing machines. Everyone who connects this machine (for electrical switchboards and sanitary communications), knows how important both of these operations. In particular, when defective connection drain pipe to the housing ganovim the pipes of communication may occur leakage of water which not only spoil the mood and the interior, but also bring tangible expenses payment of repairs to neighbors below. Even when quality of connection clamps, tightening the corrugations, and pipes drain hose of the washing machine, we recommend that from time to time to check for leaks and if necessary tighten.
When installing the radio a lot of time to spend on processing wires. First of all you need to remove the insulation, clean, tinned with stinging, and then proceed to soldering. Except for this the soldering iron, necessary lies, cutter and blade. And together with the isolation often cuts off part of the wire cores, n then have to start all over again. I propose a simple adaptation to the soldering iron. The eye eliminates unnecessary hassle, save time, improve the quality of construction works.
Radio, about which we tell, collected under the scheme direct gain works in long ranges (2000 — 740 m or 150 — 400 kHz) and medium (200 — 550 m or 520 — 1600 kHz) waves. Despite its relative simplicity, it has a sensitivity sufficient for admission to the internal magnetic antenna stations, remote distance up to 250 — 300 km With outdoor antenna reception range even more.
To calibrate, to establish or verify the performance of the radio equipment in the frequency range of 1-75 MHz allows this device. His scheme (Fig. 1) comprises a generator-the”type” with capacitive connection is made to the transistor V1. The oscillator frequency and its harmonics determine the replacement of quartz resonators B1, connected via