We offer a small material on the topic: “Electricity for beginners.” It will give an initial understanding of the terms and phenomena associated with the movement of electrons in metals.
Features of the term
Electricity is the energy of small charged particles moving in conductors in a specific direction.
With constant current, there is no change in its magnitude, as well as in the direction of movement over a certain period of time. If a galvanic cell (battery) is chosen as the current source, then the charge moves in an orderly manner: from the negative pole to the positive end. The process continues until it completely disappears.
Alternating current periodically changes magnitude as well as direction of movement.
AC transmission circuit
Let's try to understand what a phase is in a word everyone has heard, but not everyone understands its true meaning. We will not go into details and details; we will select only the material that the home craftsman needs. A three-phase network is a method of transmitting electric current, in which current flows through three different wires, and one returns it. For example, there are two wires in an electrical circuit.
Current flows through the first wire to the consumer, for example, to a kettle. The second wire is used to return it. When such a circuit is opened, there will be no passage of electric charge inside the conductor. This diagram describes a single-phase circuit. in electricity? A phase is considered to be a wire through which electric current flows. Zero is the wire through which the return is carried out. In a three-phase circuit there are three phase wires at once.
An electrical panel in the apartment is necessary for current in all rooms. are considered economically feasible, since they do not require two. When approaching the consumer, the current is divided into three phases, each with a zero. The ground electrode, which is used in a single-phase network, does not carry a working load. He is a fuse.
For example, if a short circuit occurs, there is a threat of electric shock or fire. To prevent such a situation, the current value should not exceed a safe level; the excess goes into the ground.
The manual “School for Electricians” will help novice craftsmen cope with some breakdowns of household appliances. For example, if there are problems with the functioning of the electric motor of the washing machine, current will flow to the outer metal casing.
If there is no grounding, the charge will be distributed throughout the machine. When you touch it with your hands, a person will act as a grounding conductor and receive an electric shock. If there is a ground wire, this situation will not arise.
Features of electrical engineering
The textbook “Electricity for Dummies” is popular among those who are far from physics, but plan to use this science for practical purposes.
The date of appearance of electrical engineering is considered to be the beginning of the nineteenth century. It was at this time that the first current source was created. The discoveries made in the field of magnetism and electricity managed to enrich science with new concepts and facts of important practical significance.
The “School for Electrician” manual assumes familiarity with the basic terms related to electricity.
Many physics books contain complex electrical diagrams and a variety of confusing terms. In order for beginners to understand all the intricacies of this section of physics, a special manual “Electricity for Dummies” was developed. An excursion into the world of the electron must begin with a consideration of theoretical laws and concepts. Illustrative examples and historical facts used in the book “Electricity for Dummies” will help novice electricians acquire knowledge. To check your progress, you can use assignments, tests, and exercises related to electricity.
If you understand that you do not have enough theoretical knowledge to independently cope with connecting electrical wiring, refer to reference books for “dummies”.
Safety and Practice
First you need to carefully study the section regarding safety precautions. In this case, during work related to electricity, there will be no emergency situations hazardous to health.
In order to put into practice the theoretical knowledge gained after self-studying the basics of electrical engineering, you can start with old household appliances. Before starting repairs, be sure to read the instructions included with the device. Don't forget that you shouldn't joke with electricity.
Electric current is associated with the movement of electrons in conductors. If a substance is not capable of conducting current, it is called a dielectric (insulator).
For free electrons to move from one pole to another, there must be a certain potential difference between them.
The intensity of the current passing through a conductor is related to the number of electrons passing through the cross section of the conductor.
The speed of current flow is affected by the material, length, and cross-sectional area of the conductor. As the length of the wire increases, its resistance increases.
Conclusion
Electricity is an important and complex branch of physics. The manual "Electricity for Dummies" examines the main quantities characterizing the efficiency of electric motors. The units of voltage are volts, current is measured in amperes.
Everyone has a certain power. It refers to the amount of electricity generated by a device over a certain period of time. Energy consumers (refrigerators, washing machines, kettles, irons) also have power, consuming electricity during operation. If you wish, you can carry out mathematical calculations and determine the approximate price for each household appliance.
Welcome to the electrical training video course. This video tutorial will help everyone who deals with electricity at home, as well as many novice electricians, to understand the basic terms and skills. A training video course by a young electrician will help you in life and save your life from electric shock.
Young electrician course
The author of the course, Vladimr Kozin, will help you learn with video examples what an electrical circuit is and how it consists and works. You will learn how an electrical circuit works with a switch, as well as with a two-gang switch.
Brief course content: The video course consists of 5 parts, each with 2 lessons. course Young electrician course with a total duration of about 3 hours.
- In the first part you will be introduced to the basics of electrical engineering, consider the simplest diagrams for connecting light bulbs, switches, sockets and learn about the types of electrician's tools;
- In the second part you will be told about the types and purposes of materials for the work of an electrician: cables, wires, cords and you will assemble a simple electrical circuit;
- In the third part you will learn how to connect a switch and parallel connections in electrical circuits;
- In the fourth part you will see the assembly of an electrical circuit with a two-button switch and a model of the power supply of the room;
Ultimate learning goal: In the fifth part, you will consider a complete model of the electrical supply of a room with a switch and receive tips on safety when working with electrical equipment.
Lesson 1. Young electrician course.
Lesson 2. Electrician's tool.
Lesson 3. Materials for electrical installation cable AVVG and VVG.
Lesson 4. Simple electrical circuit.
Lesson 5. Electric circuit with a switch.
Lesson 6. Parallel connection.
Lesson 7. Electric circuit with a two-gang switch
Lesson 8. Premises power supply model
Lesson 9. Model of power supply for a room with automatic shutdown
Lesson 10. Safety.
Let's start with the concept of electricity. Electric current is the ordered movement of charged particles under the influence of an electric field. The particles can be free electrons of the metal if the current flows through a metal wire, or ions if the current flows in a gas or liquid.
There is also current in semiconductors, but this is a separate topic for discussion. An example is a high-voltage transformer from a microwave oven - first, electrons flow through the wires, then ions move between the wires, respectively, first the current flows through the metal, and then through the air. A substance is called a conductor or semiconductor if it contains particles that can carry an electric charge. If there are no such particles, then such a substance is called a dielectric; it does not conduct electricity. Charged particles carry an electric charge, which is measured as q in coulombs. 
The unit of measurement of current strength is called Ampere and is designated by the letter I, a current of 1 Ampere is formed when a charge of 1 Coulomb passes through a point in an electrical circuit in 1 second, that is, roughly speaking, the current strength is measured in coulombs per second. And in essence, current strength is the amount of electricity flowing per unit time through the cross-section of a conductor. The more charged particles running along the wire, the correspondingly greater the current.
To make charged particles move from one pole to another, it is necessary to create a potential difference or – Voltage – between the poles. Voltage is measured in volts and is designated by the letter V or U. To obtain a voltage of 1 Volt, you need to transfer a charge of 1 C between the poles, while doing 1 J of work. I agree, it’s a little unclear. 
For clarity, imagine a water tank located at a certain height. A pipe comes out of the tank. Water flows through the pipe under the influence of gravity. Let water be an electric charge, the height of the water column be voltage, and the speed of water flow be electric current. More precisely, not the flow rate, but the amount of water flowing out per second. You understand that the higher the water level, the greater the pressure below will be. And the higher the pressure below, the more water will flow through the pipe because the speed will be higher.. Similarly, the higher the voltage, the more current will flow in the circuit. 
The relationship between all three considered quantities in a direct current circuit is determined by Ohm's law, which is expressed by this formula, and it sounds like the current strength in the circuit is directly proportional to the voltage, and inversely proportional to the resistance. The greater the resistance, the less the current, and vice versa. 
I'll add a few more words about resistance. It can be measured, or it can be counted. Let's say we have a conductor having a known length and cross-sectional area. Square, round, it doesn't matter. Different substances have different resistivities, and for our imaginary conductor there is this formula that determines the relationship between length, cross-sectional area and resistivity. The resistivity of substances can be found on the Internet in the form of tables. 
Again, we can draw an analogy with water: water flows through a pipe, let the pipe have a specific roughness. It is logical to assume that the longer and narrower the pipe, the less water will flow through it per unit of time. See how simple it is? You don’t even need to memorize the formula, just imagine a pipe with water.
As for measuring resistance, you need a device, an ohmmeter. Nowadays, universal instruments are more popular - multimeters; they measure resistance, current, voltage, and a bunch of other things. Let's do an experiment. I will take a piece of nichrome wire of known length and cross-sectional area, find the resistivity on the website where I bought it and calculate the resistance. Now I will measure the same piece using the device. For such a small resistance, I will have to subtract the resistance of the probes of my device, which is 0.8 ohms. Just like that!
The multimeter scale is divided according to the size of the measured quantities; this is done for higher measurement accuracy. If I want to measure a resistor with a nominal value of 100 kOhm, I set the handle to the larger nearest resistance. In my case it is 200 kilo-ohms. If I want to measure 1 kilo-ohm, I use 2 ohms. This is true for measuring other quantities. That is, the scale shows the limits of the measurement you need to fall into.
Let's continue to have fun with the multimeter and try to measure the rest of the quantities we've learned. I'll take several different DC sources. Let it be a 12 volt power supply, a USB port and a transformer that my grandfather made in his youth. 
We can measure the voltage on these sources right now by connecting a voltmeter in parallel, that is, directly to the plus and minus of the sources. Everything is clear with voltage; it can be taken and measured. But to measure current strength, you need to create an electrical circuit through which current will flow. There must be a consumer or load in the electrical circuit. Let's connect a consumer to each source. A piece of LED strip, a motor and a resistor (160 ohms).
Let's measure the current flowing in the circuits. To do this, I switch the multimeter to current measurement mode and switch the probe to the current input. The ammeter is connected in series to the object being measured. Here is the diagram, it should also be remembered and not to be confused with connecting a voltmeter. By the way, there is such a thing as current clamps. They allow you to measure current in a circuit without connecting directly to the circuit. That is, you don’t need to disconnect the wires, you just throw them on the wire and they measure. Okay, let's go back to our usual ammeter. 
So I measured all the currents. Now we know how much current is consumed in each circuit. Here we have LEDs shining, here the motor is spinning and here... So stand there, what does a resistor do? He doesn't sing us songs, doesn't light up the room, and doesn't turn any mechanism. So what does he spend the whole 90 milliamps on? This won’t work, let’s figure it out. Hey you! Aw, he's hot! So this is where energy is spent! Is it possible to somehow calculate what kind of energy is here? It turns out that it is possible. The law describing the thermal effect of electric current was discovered in the 19th century by two scientists, James Joule and Emilius Lenz. 
The law was called Joule-Lenz's law. It is expressed by this formula, and numerically shows how many joules of energy are released in a conductor in which current flows per unit time. From this law you can find the power that is released on this conductor; power is denoted by the English letter P and measured in watts. I found this very cool tablet that connects all the quantities we have studied so far.
Thus, on my table, electrical power is used for lighting, for performing mechanical work and for heating the surrounding air. By the way, it is on this principle that various heaters, electric kettles, hair dryers, soldering irons, etc. work. There is a thin spiral everywhere, which heats up under the influence of current. 
This point should be taken into account when connecting wires to the load, that is, laying wiring to sockets throughout the apartment is also included in this concept. If you take a wire that is too thin to connect to an outlet and connect a computer, kettle and microwave to this outlet, the wire may heat up and cause a fire. Therefore, there is such a sign that connects the cross-sectional area of the wires with the maximum power that will flow through these wires. If you decide to pull wires, don’t forget about it. 
Also, as part of this issue, I would like to recall the features of parallel and series connections of current consumers. With a series connection, the current is the same on all consumers, the voltage is divided into parts, and the total resistance of the consumers is the sum of all resistances. With a parallel connection, the voltage on all consumers is the same, the current strength is divided, and the total resistance is calculated using this formula.
This brings up one very interesting point that can be used to measure current strength. Let's say you need to measure the current in a circuit of about 2 amperes. An ammeter cannot cope with this task, so you can use Ohm's law in its pure form. We know that the current strength is the same in a series connection. Let's take a resistor with a very small resistance and insert it in series with the load. Let's measure the voltage on it. Now, using Ohm's law, we find the current strength. As you can see, it coincides with the calculation of the tape. The main thing to remember here is that this additional resistor should be as low resistance as possible in order to have minimal impact on the measurements. 
There is one more very important point that you need to know about. All sources have a maximum output current; if this current is exceeded, the source can heat up, fail, and in the worst case, even catch fire. The most favorable outcome is when the source has overcurrent protection, in which case it will simply turn off the current. As we remember from Ohm's law, the lower the resistance, the higher the current. That is, if you take a piece of wire as a load, that is, close the source to itself, then the current strength in the circuit will jump to enormous values, this is called a short circuit. If you remember the beginning of the issue, you can draw an analogy with water. If we substitute zero resistance into Ohm's law, we get an infinitely large current. In practice, this of course does not happen, because the source has an internal resistance that is connected in series. This law is called Ohm's law for a complete circuit. Thus, the short circuit current depends on the value of the internal resistance of the source.
Now let's return to the maximum current that the source can produce. As I already said, the current in the circuit is determined by the load. Many people wrote to me on VK and asked something like this question, I’ll exaggerate it slightly: Sanya, I have a power supply of 12 volts and 50 amperes. If I connect a small piece of LED strip to it, will it burn out? No, of course it won't burn. 50 amperes is the maximum current that the source can produce. If you connect a piece of tape to it, it will take its well, let’s say 100 milliamps, and that’s it. The current in the circuit will be 100 milliamps, and no one will burn anywhere. Another thing is that if you take a kilometer of LED strip and connect it to this power supply, then the current there will be higher than permissible, and the power supply will most likely overheat and fail. Remember, it is the consumer who determines the amount of current in the circuit. This unit can output a maximum of 2 amps, and when I short it to the bolt, nothing happens to the bolt. But the power supply doesn’t like this; it works in extreme conditions. But if you take a source capable of delivering tens of amperes, the bolt will not like this situation. 
As an example, let’s calculate the power supply that will be required to power a known section of LED strip. So, we bought a reel of LED strip from the Chinese and want to power three meters of this very strip. First, we go to the product page and try to find how many watts one meter of tape consumes. I couldn’t find this information, so there is this sign. Let's see what kind of tape we have. Diodes 5050, 60 pieces per meter. And we see that the power is 14 watts per meter. I want 3 meters, which means the power will be 42 watts. It is advisable to take a power supply with a 30% power reserve so that it does not work in critical mode. As a result, we get 55 watts. The closest suitable power supply will be 60 watts. From the power formula, we express the current strength and find it, knowing that LEDs operate at a voltage of 12 volts. It turns out that we need a unit with a current of 5 amperes. For example, we go to Ali, find it, buy it.
It is very important to know the current consumption when making any USB homemade products. The maximum current that can be taken from USB is 500 milliamps, and it is better not to exceed it.
And finally, a short word about safety precautions. Here you can see to what values electricity is considered harmless to human life. 
Each of us, when we begin to get involved in something new, immediately rushes into the “abyss of passion”, trying to complete or implement difficult projects homemade. This happened to me when I became interested in electronics. But as usually happens, the first failures diminished the passion. However, I was not used to retreating and began to systematically (literally from the beginning) comprehend the mysteries of the world of electronics. And so the “guide for beginner techies” was born.
Step 1: Voltage, Current, Resistance
These concepts are fundamental and without familiarity with them, continuing to teach the basics would be pointless. Let's just remember that every material is made up of atoms, and each atom in turn has three types of particles. An electron is one of these particles that has a negative charge. Protons have a positive charge. Conducting materials (silver, copper, gold, aluminum, etc.) have many free electrons that move randomly. Voltage is the force that causes electrons to move in a certain direction. A flow of electrons that moves in one direction is called a current. When electrons move through a conductor, they encounter some kind of friction. This friction is called resistance. The resistance “squeezes” the free movement of electrons, thus reducing the amount of current.
A more scientific definition of current is the rate of change in the number of electrons in a certain direction. The unit of current is Ampere (I). In electronic circuits, the current flowing is in the milliamp range (1 ampere = 1000 milliamps). For example, the typical current for an LED is 20mA.
The unit of measurement for voltage is Volt (V). The battery is a source of voltage. Voltages of 3V, 3.3V, 3.7V and 5V are the most common in electronic circuits and devices.
Voltage is the cause and current is the result.
The unit of resistance is Ohm (Ω).
Step 2: Power Supply
The battery is a voltage source or “proper” source of electricity. The battery produces electricity through an internal chemical reaction. It has two terminals on the outside. One of them is the positive terminal (+ V), and the other is the negative terminal (-V), or “ground”. Typically there are two types of power supplies.
- Batteries;
- Batteries.
Batteries are used once and then disposed of. Batteries can be used several times. Batteries come in many shapes and sizes, from miniature ones used to power hearing aids and wristwatches to room-sized batteries that provide backup power for telephone exchanges and computer centers. Depending on the internal composition, power supplies can be of different types. A few of the most common types used in robotics and engineering projects are:
Batteries 1.5 V
Batteries with this voltage can come in different sizes. The most common sizes are AA and AAA. Capacity range from 500 to 3000 mAh.
3V lithium coin
All of these lithium cells are rated at 3V nominal (on load) and with an open circuit voltage of around 3.6V. The capacity can reach from 30 to 500 mAh. Widely used in handheld devices due to their tiny size.
Nickel metal hydride (NiMH)
These batteries have high energy density and can charge almost instantly. Another important feature is the price. Such batteries are cheap (compared to their size and capacity). This type of battery is often used in robotics homemade products.
3.7V lithium-ion and lithium-polymer batteries
They have good discharge capacity, high energy density, excellent performance and small size. Lithium polymer battery is widely used in robotics.
9 volt battery
The most common shape is a rectangular prism with rounded edges and terminals located on top. The capacity is about 600 mAh.
Lead-acid
Lead-acid batteries are the workhorse of the entire electronics industry. They are incredibly cheap, rechargeable and easy to buy. Lead-acid batteries are used in mechanical engineering, UPS (uninterruptible power supplies), robotics and other systems where a large supply of energy is needed and weight is not so important. The most common voltages are 2V, 6V, 12V and 24V.
Series-parallel connection of batteries
The power supply can be connected in series or parallel. When connected in series, the voltage increases, and when connected in parallel, the current value increases.
There are two important points regarding batteries:
Capacity is a measure (usually in Amp-hours) of charge stored in a battery and is determined by the mass of active material contained in it. Capacity represents the maximum amount of energy that can be extracted under certain specified conditions. However, the actual energy storage capacity of a battery may vary significantly from the nominal stated value, and battery capacity is highly dependent on age and temperature, charging or discharging conditions.
Battery capacity is measured in watt-hours (Wh), kilowatt-hours (kWh), ampere-hours (Ah) or milliamp-hours (mAh). A watt-hour is the voltage (V) multiplied by the current (I) (we get power - the unit of measurement is Watts (W)) that a battery can produce for a certain period of time (usually 1 hour). Since the voltage is fixed and depends on the type of battery (alkaline, lithium, lead-acid, etc.), often only Ah or mAh is marked on the outer shell (1000 mAh = 1Ah). For longer operation of an electronic device, it is necessary to take batteries with low leakage current. To determine battery life, divide the capacity by the actual load current. A circuit that draws 10 mA and is powered by a 9-volt battery will run for about 50 hours: 500 mAh / 10 mA = 50 hours.
With many types of batteries, you cannot "drain" the energy completely (in other words, the battery cannot be completely discharged) without causing serious, and often irreparable, damage to the chemical constituents. The depth of discharge (DOD) of a battery determines the fraction of current that can be drawn. For example, if DOD is defined by the manufacturer as 25%, then only 25% of the battery capacity can be used.
Charging/discharging rates affect the nominal battery capacity. If the power supply discharges very quickly (ie, the discharge current is high), then the amount of energy that can be extracted from the battery is reduced and the capacity will be lower. On the other hand, if the battery is discharged very slowly (low current is used), then the capacity will be higher.
Battery temperature will also affect capacity. At higher temperatures, battery capacity is generally higher than at lower temperatures. However, intentionally increasing the temperature is not an effective way to increase battery capacity, as it also reduces the life of the power supply itself.
C-Capacity: The charge and discharge currents of any battery are measured relative to its capacity. Most batteries, with the exception of lead acid, are rated at 1C. For example, a battery with a capacity of 1000mAh produces 1000mA for one hour if the level is 1C. The same battery, at 0.5C, produces 500mA for two hours. With a 2C level, the same battery produces 2000mA for 30 minutes. 1C is often referred to as the one-hour discharge; 0.5C – like a two-hour clock and 0.1C – like a 10-hour clock.
Battery capacity is usually measured using an analyzer. Current analyzers display information as a percentage based on the rated capacity value. A new battery sometimes produces more than 100% current. In this case, the battery is simply rated conservatively and can last longer than what the manufacturer specifies.
The charger can be selected in terms of battery capacity or C value. For example, a charger rated C/10 will fully charge the battery in 10 hours, a charger rated 4C would charge the battery in 15 minutes. Very fast charging rates (1 hour or less) usually require the charger to carefully monitor battery parameters, such as voltage limits and temperature, to prevent overcharging and damage to the battery.
The voltage of a galvanic cell is determined by the chemical reactions that take place inside it. For example, alkaline cells are 1.5 V, all lead acid cells are 2 V, and lithium cells are 3 V. Batteries can be made up of multiple cells, so you will rarely see a 2 V lead acid battery. They are typically wired together internally to provide 6V, 12V, or 24V. Keep in mind that the nominal voltage of a "1.5V" AA battery actually starts at 1.6V, then quickly drops to 1.5, then slowly drifts down to 1.0 V, at which point the battery is considered 'discharged'.
How to choose the best battery for crafts?
As you already understand, there are many types of batteries with different chemical compositions available in the public domain, so it is not easy to choose which power is best for your particular project. If the project is very energy dependent (large sound systems and motorized homemade products) should choose a lead-acid battery. If you want to build a portable under the tree, which will consume little current, then you should choose a lithium battery. For any portable project (light weight and moderate power supply), choose a lithium-ion battery. You can choose a cheaper nickel metal hydride (NIMH) battery, although they are heavier, but are not inferior to lithium-ion in other characteristics. If you would like to do a power-hungry project, a lithium-ion alkaline (LiPo) battery would be the best option because it is small in size, lightweight compared to other types of batteries, recharges very quickly and delivers high current.
Do you want your batteries to last a long time? Use a high quality charger that has sensors to maintain proper charge levels and low current charging. A cheap charger will kill your batteries.
Step 3: Resistors
A resistor is a very simple and most common element in circuits. It is used to control or limit current in an electrical circuit.
Resistors are passive components that only consume energy (and cannot produce it). Resistors are typically added to a circuit where they complement active components such as op-amps, microcontrollers, and other integrated circuits. They are typically used to limit current, separate voltages, and separate I/O lines.
The resistance of a resistor is measured in Ohms. Larger values can be associated with the kilo-, mega-, or giga prefix to make the values easy to read. You can often see resistors labeled kOhm and MOhm range (mOhm resistors are much less common). For example, a 4,700Ω resistor is equivalent to a 4.7kΩ resistor and a 5,600,000Ω resistor can be written as 5,600kΩ or (more commonly) 5.6MΩ.
There are thousands of different types of resistors and many companies that make them. If we take a rough gradation, there are two types of resistors:
- with clearly defined characteristics;
- general purpose, whose characteristics may “walk” (the manufacturer himself indicates the possible deviation).
Example of general characteristics:
- Temperature coefficient;
- Voltage factor;
- Frequency range;
- Power;
- Physical size.
According to their properties, resistors can be classified as:
Linear resistor- a type of resistor whose resistance remains constant with increasing potential difference (voltage) that is applied to it (the resistance and current that passes through the resistor does not change with the applied voltage). Features of the current-voltage characteristic of such a resistor are a straight line.
Non linear resistor is a resistor whose resistance changes depending on the value of the applied voltage or the current flowing through it. This type has a non-linear current-voltage characteristic and does not strictly follow Ohm's law.
There are several types of nonlinear resistors:
- NTC (Negative Temperature Coefficient) resistors - their resistance decreases with increasing temperature.
- PEC (Positive Temperature Coefficient) resistors - their resistance increases with increasing temperature.
- LZR resistors (Light-dependent resistors) - their resistance changes with changes in the intensity of the light flux.
- VDR resistors (Voltage Dependent Resistors) - their resistance critically decreases when the voltage value exceeds a certain value.
Non-linear resistors are used in various projects. LZR is used as a sensor in various robotics projects.
In addition, resistors come with a constant and variable value:
Fixed resistors- types of resistors whose value is already set during production and cannot be changed during use.
Variable resistor or potentiometer – a type of resistor whose value can be changed during use. This type usually has a shaft that is turned or moved manually to change the resistance value over a fixed range, e.g. 0 kOhm to 100 kOhm.
Resistance Store:
This type of resistor consists of a "package" that contains two or more resistors. It has several terminals through which the resistance value can be selected.
The composition of resistors is:
Carbon:
The core of such resistors is cast from carbon and a binder, creating the required resistance. The core has cup-shaped contacts that hold the resistor rod on each side. The entire core is filled with a material (like Bakelite) in an insulated casing. The housing has a porous structure, so carbon composite resistors are sensitive to relative ambient humidity.
These types of resistors usually produce noise in the circuit due to the electrons passing through the carbon particles, so these resistors are not used in "important" circuits, although they are cheaper.
Carbon deposition:
A resistor that is made by depositing a thin layer of carbon around a ceramic rod is called a carbon deposited resistor. It is made by heating ceramic rods inside a flask of methane and depositing carbon around them. The value of the resistor is determined by the amount of carbon deposited around the ceramic rod.
Film resistor:
The resistor is made by depositing sprayed metal in a vacuum onto a ceramic rod base. These types of resistors are very reliable, have high stability and also have a high temperature coefficient. Although they are expensive compared to others, they are used in basic systems.
Wirewound resistor:
A wirewound resistor is made by winding metal wire around a ceramic core. The metal wire is an alloy of various metals selected according to the stated features and resistance of the required resistor. This type of resistor has high stability and can also handle high power, but they are generally bulkier than other types of resistors.
Metal-ceramic:
These resistors are made by baking some metals mixed with ceramics on a ceramic substrate. The proportion of the mixture in a mixed metal-ceramic resistor determines the resistance value. This type is very stable and also has precisely measured resistance. They are mainly used for surface mounting on printed circuit boards.
Precision resistors:
Resistors whose resistance value lies within a tolerance, so they are very accurate (the nominal value is in a narrow range).
All resistors have a tolerance, which is given as a percentage. The tolerance tells us how close to the nominal value the resistance can vary. For example, a 500Ω resistor that has a tolerance value of 10% could have a resistance between 550Ω or 450Ω. If the resistor has a 1% tolerance, the resistance will only change by 1%. So a 500Ω resistor can vary from 495Ω to 505Ω.
A precision resistor is a resistor that has a tolerance level of only 0.005%.
Fusible resistor:
The wirewound resistor is designed to burn out easily when the rated power exceeds the limiting threshold. Thus the fusible resistor has two functions. When the supply is not exceeded, it serves as a current limiter. When the rated power is exceeded, the oa functions as a fuse; once blown, the circuit becomes open, which protects the components from short circuits.
Thermistors:
A heat-sensitive resistor whose resistance value changes with operating temperature.
Thermistors display either positive temperature coefficient (PTC) or negative temperature coefficient (NTC).
How much resistance changes with changes in operating temperature depends on the size and design of the thermistor. It is always better to check the reference data to know all the specifications of the thermistors.
Photoresistors:
Resistors whose resistance changes depending on the light flux that falls on its surface. In a dark environment, the resistance of the photoresistor is very high, several M Ω. When intense light hits the surface, the resistance of the photoresistor drops significantly.
Thus, photoresistors are variable resistors, the resistance of which depends on the amount of light that falls on its surface.
Leaded and leadless types of resistors:
Terminal Resistors: This type of resistor was used in the earliest electronic circuits. The components were connected to the output terminals. Over time, printed circuit boards began to be used, into the mounting holes of which the leads of radio elements were soldered.
Surface Mount Resistors:
This type of resistor has become increasingly used since the introduction of surface mount technology. Typically this type of resistor is created by using thin film technology.
Step 4: Standard or Common Resistor Values
The designation system has origins that go back to the beginning of the last century, when most resistors were carbon with relatively poor manufacturing tolerances. The explanation is quite simple - using a 10% tolerance you can reduce the number of resistors produced. It would be ineffective to produce 105 ohm resistors, since 105 is within the 10% tolerance range of a 100 ohm resistor. The next market category is 120 ohms because a 100 ohm resistor with 10% tolerance will have a range between 90 and 110 ohms. A 120 ohm resistor has a range between 110 and 130 ohms. By this logic, it is preferable to produce resistors with a 10% tolerance of 100, 120, 150, 180, 220, 270, 330 and so on (rounded accordingly). This is the E12 series shown below.
Tolerance 20% E6,
Tolerance 10% E12,
Tolerance 5% E24 (and usually 2% tolerance)
Tolerance 2% E48,
E96 1% tolerance,
E192 0.5, 0.25, 0.1% and higher tolerances.
Standard resistor values:
E6 series: (20% tolerance) 10, 15, 22, 33, 47, 68
E12 series: (10% tolerance) 10, 12, 15, 18, 22, 27, 33, 39, 47, 56, 68, 82
E24 series: (5% tolerance) 10, 11, 12, 13, 15, 16, 18, 20, 22, 24, 27, 30, 33, 36, 39, 43, 47, 51, 56, 62, 68, 75, 82, 91
E48 series: (2% tolerance) 100, 105, 110, 115, 121, 127, 133, 140, 147, 154, 162, 169, 178, 187, 196, 205, 215, 226, 237, 249, 261, 274, 287, 301, 316, 332, 348, 365, 383, 402, 422, 442, 464, 487, 511, 536, 562, 590, 619, 649, 681, 715, 750, 787, 825, 866 , 909, 953
E96 series: (1% tolerance) 100, 102, 105, 107, 110, 113, 115, 118, 121, 124, 127, 130, 133, 137, 140, 143, 147, 150, 154, 158, 162, 165, 169, 174, 178, 182, 187, 191, 196, 200, 205, 210, 215, 221, 226, 232, 237, 243, 249, 255, 261, 267, 274, 280, 287, 294 , 301, 309, 316, 324, 332, 340, 348, 357, 365, 374, 383, 392, 402, 412, 422, 432, 442, 453, 464, 475, 487, 491, 511, 523, 536 , 549, 562, 576, 590, 604, 619, 634, 649, 665, 681, 698, 715, 732, 750, 768, 787, 806, 825, 845, 866, 887, 909, 931, 959, 976
E192 series: (0.5, 0.25, 0.1 and 0.05% tolerance) 100, 101, 102, 104, 105, 106, 107, 109, 110, 111, 113, 114, 115, 117, 118, 120, 121, 123, 124, 126, 127, 129, 130, 132, 133, 135, 137, 138, 140, 142, 143, 145, 147, 149, 150, 152, 154, 156, 158 , 160, 162, 164, 165, 167, 169, 172, 174, 176, 178, 180, 182, 184, 187, 189, 191, 193, 196, 198, 200, 203, 205, 208, 210, 213 , 215, 218, 221, 223, 226, 229, 232, 234, 237, 240, 243, 246, 249, 252, 255, 258, 261, 264, 267, 271, 274, 277, 280, 284, 287 , 291, 294, 298, 301, 305, 309, 312, 316, 320, 324, 328, 332, 336, 340, 344, 348, 352, 357, 361, 365, 370, 374, 379, 383, 388 , 392, 397, 402, 407, 412, 417, 422, 427, 432, 437, 442, 448, 453, 459, 464, 470, 475, 481, 487, 493, 499, 505, 511, 517, 523 , 530, 536, 542, 549, 556, 562, 569, 576, 583, 590, 597, 604, 612, 619, 626, 634, 642, 649, 657, 665, 673, 681, 690, 698, 706 , 715, 723, 732, 741, 750, 759, 768, 777, 787, 796, 806, 816, 825, 835, 845, 856, 866, 876, 887, 898, 909, 920, 931, 942, 953 , 965, 976, 988
When designing hardware, it is best to stick to the lowest section, i.e. It's better to use E6 rather than E12. In such a way that the number of different groups in any equipment is minimized.
To be continued
Nowadays, anyone can become familiar with the basics of electrical engineering without even leaving their home. It’s best to start this exciting activity by getting acquainted with a simplified electrical diagram for wiring and connecting switches, sockets and lighting fixtures in your own apartment. Such schemes belong to standard design solutions and are widely used for power supply of standard industrial and residential premises, as well as for temporary connection to the power supply network of a number of construction sites.
The first (at the same time the largest and most important) element in a long chain of equipment for typical residential electrical wiring is the electrical panel, to which power is supplied through a circuit breaker (or plug fuse) from the main distribution panel located on the access platform. The apartment panel usually includes an electric meter, several circuit breakers, a residual current device (RCD), a mounting DIN rail and a number of auxiliary buses. It is from this input panel that the power supply to all rooms in your apartment is organized.
Several power supply lines (their number depends on the number of rooms and the power of electrical loads), consisting of two wires - phase and neutral (or three, if there is a grounding line), are routed through dedicated circuit breakers to separate rooms of the apartment.
Electrical wiring throughout the apartment is carried out by organizing branches from the main wiring line, which are necessary to connect individual consumers - an electric bell, groups of plug sockets or switches. For these purposes, installation distribution boxes are used, which are plastic cups equipped with inlet and outlet openings for wires and a lid. Inside the boxes there are special screw terminals for connecting switched installation wires. But as a rule, the wires in the box are simply twisted (the so-called twist) and insulated from each other (usually wrapped with electrical tape or heat-shrink tubing). It is also recommended to use clamps (Wago clamps are widely used in our country), or PPE connecting clamps (caps with a spring inside).
It should be noted that all indoor electricity consumers (bells, various lighting fixtures along with switches, household appliances, air conditioners, etc.) are connected to the apartment wiring in parallel. With such a connection scheme, a malfunction or disconnection of one of these consumers will not cause a “de-energization” of the remaining devices, which is inevitable if they are connected in series. An example of a series connection of individual elements of electrical wiring is the connection of any lighting fixture and its switch.
Thus, the electrical wiring lines are first connected to the distribution boxes located in each room and only after them are they distributed to individual loads (lighting fixtures with switches, sockets, etc.).
From the connection diagram for switches and lamps, we see that phase wires (red) and neutral wires (blue) approach the distribution box and branch off from it. It is the outgoing phase wire (in no case neutral!) that must be connected to one of the contacts of the switch. The neutral wire must go to the common contact of the lamps that make up the lamp. The wires coming from the switch (green in the figure) are connected to the common contact of each of the two groups of lamps of the lamp in question. Please note that the figure shows a version of a two-key switch with two groups of lamps and a version of a single-key switch.
Connecting sockets after the distribution box is done in a simpler way - the phase and neutral conductors (and grounding, if any) are connected directly to the corresponding (randomly selected) contacts of the socket itself. A pair of these conductors from an already connected outlet is led to the second, and, if necessary, to the third outlet (this type of connection is called a “loop” connection).
It is very important to take into account the fact that with a parallel circuit for connecting consumers, it is not allowed to increase their total number above a certain value. With parallel power supply, each newly added electrical appliance (new outlet) increases the load on the part of the electrical wiring common to the entire apartment. At the maximum value of the total current in the circuit (in the case when all devices are turned on), the overcurrent protection device will definitely operate - the same circuit breaker on the panel from which this line is powered. He will simply disconnect this branch from the general power supply circuit of the apartment.
If your machine is selected incorrectly (has an overestimated value of the overload response current), then the consequences may be much more disastrous - the wires may simply not withstand the strength of the current passing through them and will catch fire due to overheating.
This is why it is so important to learn how to select the correct circuit breaker for each load line and accurately calculate the cross-section of the wires operating in these lines.
As a rule, in a typical apartment wiring, a copper wire with a cross-section of 1.5 mm 2 is laid on the lighting lines, and 2.5 mm 2 on the socket lines.
