Electrical engineering made easy
The processes that occur with electric current can be most easily explained with the help of a plumbing rough. A certain amount of water flows through such a pipe under pressure.
- Water pressure can be compared to voltage measured in volts (IN)
- The amount of water flowing over a certain time can be compared to an electric current measured in amperes (A)
- If you multiply the voltage by the current, then you get the electrical power, measured in watts (Tue)
- And we get a completely different value when we divide the voltage by the current strength. As a result of division, resistance is obtained, measured in ohms (Ohm).
Resistance can be compared to a stopcock in a water pipe. When the faucet is open, the resistance is zero, the water flows freely. When the faucet is closed, the resistance increases to infinity (∞), the stream stops.
Each consumer of electricity is a kind of resistance, which, for its perfect functioning, must receive enough electric current. Therefore, a small control bulb needs only thin wires; a powerful starter, on the contrary, needs a particularly thick wire.
Voltage measurement. control light
The control lamp has a needle contact, with which the needle can simply pierce the insulation of the cable under test. The light bulb cable terminal is clamped somewhere near bare metal, at the so-called "masses" car. First of all, the light bulb indicates whether there is any voltage at all. By the brightness of the light bulb, you can judge the magnitude of the voltage.
Measuring device with diodes
With help usually!! test lamp should not be measured in electronic components. Such a test lamp consumes too much power, and this may cause damage to electronic parts. If someone wants to take measurements on electronic devices, he must purchase a measuring device with light diodes.
Voltmeter
Using a voltmeter or a multifunctional device with an appropriate measuring range, you can, for example, measure the voltage of a battery. If the device shows only 10.4 volts, then one of the battery cells has a short circuit. It is also interesting to measure the battery voltage. when the starter is running. If in this case the voltage is less than 8 V, then the battery is bad.
To measure the wire marked with the sign «-», connects to the negative terminal of the battery or to "mass". Wire with designation «+» of the measuring device is connected to the wire under test or to the positive terminal of the battery.
Current measurement
With the help of an ammeter or a multifunctional device with an appropriate measuring range, it is possible to determine whether current flows to the consumer or not. To do this, the current circuit must be open, and the measuring device is switched on in the gap. In the car, for this purpose, one of the connectors can be removed and then the measuring device connected between the connector and the contact tongue.
For example, the electric current is measured if there is a suspicion that the current consumer is somewhere in the on-board network during the night "devastated" battery. To find this place, you need to remove "mass" battery wire and connect an ammeter between the battery pole and "massive" wire. If the instrument indicates that current is flowing, a specific current circuit is established. To do this, in a niche with fuses, remove one fuse after another and instead connect the ammeter clamps to the contact tabs. In this way, you can determine which circuit has current leakage. Using the fuse table, it is then determined which consumers are included in this current circuit; then check them one by one.
Resistance measurement
Resistance measurement makes it possible, for example, to find out whether current flows through a given wire (then the measured resistance value is zero) Or is there a broken circuit somewhere? (then the resistance is infinity). To measure resistance, the meter must have its own power supply.
1 - Consumer. The figures schematically illustrate how to connect the appropriate measuring device for measuring voltage, current and resistance (from left to right). A circle with an arrow is a measuring device. Consumers are, for example, a lamp, an electric motor, etc.
Basic concepts of electronics
The very word "electronics" means that this industry is based on the use of electrons. Electrons are extremely small particles, of which a small atom also partially consists. All electrically conductive materials (special term: conductors) electrons make the current flow. In this case, the electrons in the conductor move from atom to atom. Materials that do not conduct electricity also have electrons. But they are strongly bound to the nucleus of the atom and cannot move further. Therefore, current does not flow.
The third group of materials is the so-called semiconductors. Are these crystals (in most cases germanium or silicon), which are processed in such a way that electrons are either absent in their structure, or they are present in excess. This is the reason for the desired effect: an electric current can flow through the plates of crystals only under certain conditions. If the conditions are not met, the current flow stops. Then a blocking layer is formed. This property finds application in diodes and transistors. In the electrical equipment of motor vehicles, semiconductor structural elements are rarely found in a single quantity. As a rule, they are available in large numbers in complete circuits, for example, in a generator regulator.
Semiconductors
The transistor only passes current when the third transistor connection has voltage. If this voltage is large, a lot of current flows. With a small voltage, respectively, the current is less. It can be compared to a faucet. The more the valve is open, the more water flows.
A diode conducts electricity in only one direction. If the electric current flows in the opposite direction, the diode blocks its passage. It's like a tire valve, meaning air can be pumped in, but it doesn't come out anymore.
Light Diode: A semiconductor crystal emits light as long as there is voltage. At its core, it is similar to an incandescent lamp, but in this case there is no filament.
Other structural elements
Resistance function (rheostat) - stop the flow of electric current, reduce its magnitude.
The capacitor acts like a small battery; it can accumulate electricity for a certain time. The capacitor is used to smooth out voltage fluctuations and dampen voltage peaks.
If a time delay is desirable in some circuit, then a capacitor with resistance is connected to the time-regulating link.
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