The general pattern of our time is the narrowing of the gap between a particular discovery and its implementation. Once this interval reached hundreds of years, now it has decreased to a minimum. For example, the introduction of photography is 112 years behind its opening. Mineral fertilizers began to be used 70 years after their creation, telephone communications - after 50 years, radio broadcasting - after 35, radar - after 15, television - after 12, an atomic bomb - after 6 years, a transistor - after 3, and a laser - after only 2 of the year.

The beginning of the technical use of superconductors dates back to 1955, when the first electromagnet was created with their help. 56 years have passed since the discovery of superconductivity to its introduction. What is the matter? According to some British physicists, this delay is due to two reasons: the insufficient development of cryogenic technology and the discovery of only soft, pure superconductors ...

In the previous parts of the article, thermistors and thermocouples were described. This article will talk about other types of temperature sensors.

In the same temperature ranges as semiconductor thermal resistances, ordinary diodes or pn junction transistors are often used to measure and control temperature.

The use of these devices is explained by the fact that they have a temperature coefficient of voltage TKN. For all semiconductors, it is negative and approximately the same: -2mV / ° C. To verify this, it is enough to do the simplest experiment described below. If a Chinese-made digital multimeter at room temperature “rings” silicon diodes or transistor junctions, then the numbers about 690 - 700 are displayed on the indicator ...

Externally, the thermocouple is arranged very simply: two thin wires are simply welded together in the form of a neat little ball. Some modern Chinese-made digital multimeters are equipped with a thermocouple, which allows you to measure the temperature not less than 1000 ° C, which makes it possible to check the heating temperature of the soldering iron or iron, which they are going to smooth the laser print to fiberglass, as well as in many other cases.

The design of such a thermocouple is very simple: both wiring are hidden in a fiberglass tube, and even do not have insulation noticeable to the eye. On the one hand, the wires are neatly welded, and on the other they have a plug for connecting to the device. Even with such a primitive design, the results of temperature measurement are not in doubt, unless, of course, the accuracy of the measurement is required ...

Multi-tariff meters are becoming more common when accounting consumption electricity. How quickly will the costs of its acquisition and installation pay off?

It seems obvious the economic effect of the use of multi-tariff metering devices for electric energy. The essence of the work of this electric meter is that, depending on the program laid down in it, it takes into account the energy consumption not by one digit, but by several. The entire amount of electrical energy consumed by the consumer is divided into two time periods: day and night.

The tariff for electricity consumed during the daytime is normal, set by the regional energy commissions. But the electricity “burned” at night costs exactly half the price ...

How badly will a person be injured by electric shock when they come under voltage? It depends on many factors, such as the type of current in the network, the path of the current passing through the victim’s body, the electrical resistance of the body, and, of course, the touch voltage.

Here about the last factor and I would like to talk in more detail. At one time I had to listen to lectures on electrical safety from a professor at a local university. From year to year I had to see how the professor performs the same trick in front of an audience.

The trick was this: the professor, a respected man of advanced years, openly hooligans, bending a metal paper clip and shoving it with his bare hands alternately in both sockets of a 220-volt electrical outlet. There were no health consequences for the professor ...

Nowadays, the number and variety of household appliances in apartments is increasing every day, but the number of outlets remains the same.

Most people living in old apartments with two or three sockets per room have to somehow get out and use tees and extension cords to connect various electrical appliances.

In this article, let's understand why it is so dangerous to use tees and extension cords?

Firstly, it is not safe. in terms of possible electric shock. The greatest danger is the use of extension cords in bathrooms. The extension cord is subject to constant physical stress, twisting. Homemade extension cords are especially dangerous in this regard ...

Lighting, light in our homes. What else could be so popular and familiar? Even a beautiful chandelier attracts our eyes only while it is new. And then, the look was used to, and nobody was just noticing it. In fact, the light conceals many more interesting opportunities that will make your life more beautiful and interesting. More precisely, it is not so much the light itself as modern management methods.

For example, such an interesting function as controlling the brightness of light sources. Firstly, there are physiological reasons for this. Indeed, for different types of human activity, there are different requirements for lighting. For example, requirements for lighting a student’s workplace. Daylight may be sufficient, but artificial lighting is required at night ...

Currently, for the installation of home wiring, wires and cables are used exclusively with copper conductors. Wires and cables with aluminum conductors for internal wiring not allowed.

Wires and cables are single-core and multi-core. Stranded wires and cables have in their common sheath two or more wires that are reliably isolated from each other. An example of a stranded wire is a wire of the PRTO brand (a wire with a copper core with rubber insulation in a braid of cotton yarnimpregnated with antiseptic composition).

Conductors of single-core and multicore wires and cables can be manufactured as single-wire and multi-wire. Cables and wires differ from each other by the type of sheath and names. The sheath of wires and cables serves ...