Two soldered wires, and replace the battery. Scheme, description

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ENCYCLOPEDIA OF RADIO ELECTRONICS AND ELECTRICAL ENGINEERING
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Two soldered wires, and replace the battery. Encyclopedia of radio electronics and electrical engineering

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Encyclopedia of radio electronics and electrical engineering / Beginner radio amateur

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In new garden plots, electricity is usually supplied last, which, we agree, is very inconvenient. This is where the power plant that we offer will help us out. It will allow you to listen to the radio and even illuminate the room.

The installation uses the effect of the appearance of EMF in circuits consisting of various metals or semiconductors. You have already read about this on the pages of the magazine in the article by A. Savelyev.

Let's take two electrical conductors, which are made of different metals, and solder their ends. Now, when one end is heated and the other end is cooled, an electric current will flow in the circuit of conductors - thermoelements (thermocouples). The created EMF will depend on the temperature difference, as well as on the selection of materials that make up the thermoelement. The efficiency of such converters does not exceed 5-6%. The maximum temperature to which a thermocouple can be heated is determined by the melting point of the elements. For example, a pair of copper - constant can be heated up to 350 degrees, steel - constantan up to 315 ... 649 degrees - depending on the diameter of the wire, and a pair of chromel - alumel up to 700 ... 1152 degrees. To increase the efficiency, as you understand, it is necessary to maximize the temperature difference between the cold and hot junctions. But at the same time, when selecting pairs, it is necessary to take into account the thermal conductivity of materials. It is better if the ratio between the average thermal conductivity and the average electrical conductivity is minimal.

Two soldered wires, and replace the battery

When selecting materials, it is convenient to use the table below. It is better to choose those of them that are as far away as possible from each other in a column. For example, steel (top), constantan (bottom) will give good results, while copper and silver are low-active elements. The antimony-bismuth pair is the best, but practically inaccessible to the amateur. Although it gives the largest thermoelectric voltage - about 112 μV / deg., The materials are too specific and rare.

In addition, each material listed in the table has a negative potential in relation to all others above. For example, in a steel-constant pair, steel will have a relative potential of plus, and constantan will have a minus. In a chromel-alumel thermocouple, chromel has a plus, and alumel has a minus.

To make a battery, you will need two pieces of wire (steel and constantan) with a diameter of 1,3 mm, each 18 m long. The ends of each element are cleaned and twisted together, then welded. The elements are mounted on an asbestos-cement panel (Fig. 1). When tested, individual thermocouples should give a current of about 22 mA when heated with a match and about 30 mA when heated with an alcohol burner. With a normal burning spirit lamp, the battery will give 1,5 V at a tone of 0,3 A (Fig. 2). By making a set of such batteries and connecting them in parallel, you can get a direct electric current with a power sufficient to power a transistor receiver and similar electrical appliances. It is only necessary to remember that when connected in series, the internal resistance of the battery increases.

The multiple battery pack can be used with a kerosene lamp, metal stovepipe, or other similar heat source.

Author: K.Vladimirov

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