LED assemblies 12 volts. Good and bad LED circuits

12 volt LEDs for cars have 11 main advantages, which it will be useful for you to know about, they are gradually replacing old light bulbs from everyday use, even in cars, drivers are trying to install LED backlighting. Today it is widely used for:

• car interior lighting;
• dashboard lighting;
• trunk lighting
• replacing conventional light bulbs installed in headlights

Selection diagram for LED lamps for a car

The demand for LEDs is quite justified, because they have many advantages over incandescent lamps and mercury lamps.

12 volt LEDs for cars: their advantages and efficiency

1. Economical energy consumption. LED lamps consume 70% less electricity than incandescent lamps.
2. LEDs do not burn out, so they do not have to be replaced even after a long period of use.
3. They do not require special conditions for disposal, because LEDs are not hazardous to the environment, unlike mercury lamps.
4. The brightness of the lighting remains constant, regardless of the service life of the lamps.
5. LED lamps are very durable. They are made of aluminum and polycarbonate glass that can withstand heavy impact loads.
6. LEDs provide good illumination. With this light, all objects and their colors are clearly visible. 12 volt LEDs for cars are ideal for low beam.
7. LEDs turn on instantly and can operate at any ambient temperature.
8. LED lighting does not cause eye fatigue because it does not have a low-frequency ripple effect.
9. Powerful flashlights made from LEDs do not dazzle your eyes.
10. They heat up less, so they will not damage the optics in the car.

• LED devices produce brighter light when compared to incandescent light. Therefore, your car with LED headlights will be more visible on the track. 12 volt car LED bulbs are widely used in fog lights. A strobe light with LEDs will help make your car more visible on the road at any time of the day. An alarm with a bright LED will scare away burglars.

Ultra-bright automotive LED lamps - design features

The design of LED light bulbs with E27 base can be seen in Figure 1

Types of LEDs that are used in cars

To obtain the required lighting brightness in different parts of the car, the following types of LED lamps are used:

• The H1 base is used in the front high beam headlights. Truck drivers often use 24-volt LED car lamps, which successfully replace xenon lamps;
• To make the low beam lights brighter, install H4 and H7 lamps.
• in the trunk and interior they use C5W, W5W, BA9S;

• rear license plate or instrument panel illumination is mounted using T5 lamps;
• For fog lights, lamps H1, H3, HB3, HB2, H4, H7, H11 are suitable. 12 volt automotive LEDs are used more often than others. A 12 volt LED lamp powered by a battery can also be used for low beam lighting.
• BA15S lamps are suitable for turning signals. This type of LEDs corresponds to P21W.
• For tail lights, BAY15D is installed. In European cars, this type of two-pin LEDs is designated P21/5W.

Popular 12 volt LED lamps. Manufacturers and their price categories

Among all purchased LED lamps for cars, the leading products are from the following companies:

• KARKAM Electronics. The company produces LED lamps for automotive lighting based on CREE LEDs. A set of two H4 lamps will cost 2990 rubles. 12 volt LEDs for cars from this company are often used in fog lights.
• OSRAM. OSRAM LED products are manufactured with precise adherence to technology, with careful quality control of raw materials at all stages of the process and at each of the OSRAM factories located around the world. The price of Osram P21W LEDriving Premium is about 1200 rubles.
• Philips Automotive. The company is a world leader in the production of LED light bulbs. The Philips X-treme Ultinon LED H4 lamp will cost RUB 3,847. Common
  LEDs for a 12 volt car from Philips will cost 600-700 rubles. Popular hb4 LEDs can be purchased for approximately 4,000 rubles.
• Lighthouse. The H11 lamp from the famous Russian company will cost 500 rubles.

24 volt LEDs for cars (China) are also in demand on the market due to their low cost. LED lamps for a 24 volt car can be bought for an average of 1000 rubles.

Installation features and connection diagrams. Why can't LEDs be directly connected to the car's network?

The voltage in the car's electrical network ranges from 12.5 volts to 14.5 volts, and the operating voltage of the LED is about 3 volts, so they cannot be directly connected to the on-board network. Before connecting each element to the battery, you need to determine the polarity of the LED. The negative is connected to the cathode of the LED, and the positive is connected to a direct current source. It is impossible to connect LEDs to 12 volts of a car without a resistor.

To create the backlight, ready-made tapes are used. They are made from several LEDs and resistors. Each such cluster is designed for a specific voltage.

If the electrical parameters meet those acceptable for your vehicle, then installation can begin. If necessary, LED strips can be divided into parts. This must be done according to the markings provided by the manufacturer so as not to damage the electrical circuit.

How to assemble a LED circuit yourself. Why do you need a voltage stabilizer and resistor?

A circuit of three white LEDs with a voltage of 3.5 volts and a resistor is easy to assemble with your own hands. All light bulbs are connected in series, and the difference with the voltage of the car electrical network is compensated using a 100 Ohm resistor and a power of 0.5 Watts. It is also connected in series in the circuit. Several chains can be assembled and connected in parallel so that all sections have the same voltage drop. The light bulbs are assembled on foil PCB.

A voltage stabilizer connected to the circuit will help prevent the headlights from dimming the moment the car starts moving.

To complete the assembly you will need plastic clamps and a soldering iron. If you can solder professionally and understand the electrical wiring of your vehicle, then you can safely get to work. If you do not have such knowledge, then it is better to entrust the work to professionals so as not to risk your car. They will do this work quickly and efficiently. Below is a video with a test of 12 volt LEDs.

An LED is a diode that lights up when current flows through it. In English, an LED is called a light emitting diode, or LED.

The color of the LED glow depends on the additives added to the semiconductor. For example, impurities of aluminum, helium, indium, and phosphorus cause a glow from red to yellow. Indium, gallium, nitrogen makes the LED glow from blue to green. When a phosphor is added to a blue crystal, the LED will glow white. Currently, the industry produces LEDs of all colors of the rainbow, but the color does not depend on the color of the LED housing, but on the chemical additives in its crystal. An LED of any color can have a transparent body.

The first LED was manufactured in 1962 at the University of Illinois. In the early 1990s, bright LEDs appeared, and a little later, super bright ones.
The advantages of LEDs over incandescent light bulbs are undeniable, namely:

* Low power consumption - 10 times more economical than light bulbs
* Long service life - up to 11 years of continuous operation
* High durability - not afraid of vibrations and shocks
* Wide variety of colors
* Ability to operate at low voltages
* Environmental and fire safety - no toxic substances in LEDs. LEDs do not heat up, which prevents fires.

LED markings

Rice. 1. Design of 5 mm indicator LEDs

An LED crystal is placed in the reflector. This reflector sets the initial scattering angle.
The light then passes through the epoxy resin housing. It reaches the lens - and then it begins to scatter on the sides at an angle depending on the design of the lens, in practice - from 5 to 160 degrees.

Emitting LEDs can be divided into two large groups: visible LEDs and infrared (IR) LEDs. The former are used as indicators and illumination sources, the latter - in remote control devices, infrared transceiver devices, and sensors.
Light-emitting diodes are marked with a color code (Table 1). First, you need to determine the type of LED by the design of its housing (Fig. 1), and then clarify it by color markings in the table.

Rice. 2. Types of LED housings

LED colors

LEDs come in almost every color: red, orange, amber, amber, green, blue and white. Blue and white LED are a little more expensive than other colors.
The color of LEDs is determined by the type of semiconductor material from which it is made, and not by the color of the plastic of its housing. LEDs of any color come in a colorless case, in which case the color can only be found out by turning it on...

Table 1. LED markings

Multicolor LEDs

A multicolor LED is designed simply; as a rule, it is red and green combined into one housing with three legs. By changing the brightness or the number of pulses on each crystal, you can achieve different glow colors.

LEDs are connected to a current source, anode to positive, cathode to negative. The negative (cathode) of an LED is usually marked with a small cut of the body or a shorter lead, but there are exceptions, so it is better to clarify this fact in the technical characteristics of a particular LED.

In the absence of these marks, the polarity can be determined experimentally by briefly connecting the LED to the supply voltage through the appropriate resistor. However, this is not the best way to determine polarity. In addition, in order to avoid thermal breakdown of the LED or a sharp reduction in its service life, it is impossible to determine the polarity “at random” without a current-limiting resistor. For quick testing, a resistor with a nominal resistance of 1k ohms is suitable for most LEDs as long as the voltage is 12V or less.

A word of warning: do not point the LED beam directly at your eye (or your friend’s eye) at close range, as this can damage your vision.

Supply voltage

The two main characteristics of LEDs are voltage drop and current. Typically, LEDs are designed for a current of 20 mA, but there are exceptions, for example, quad-chip LEDs are usually designed for 80 mA, since one LED housing contains four semiconductor crystals, each of which consumes 20 mA. For each LED, there are permissible values ​​of supply voltage Umax and Umaxrev (for direct and reverse switching, respectively). When voltages above these values ​​are applied, an electrical breakdown occurs, as a result of which the LED fails. There is also a minimum value of the supply voltage Umin at which the LED glows. The range of supply voltages between Umin and Umax is called the “working” zone, since this is where the LED operates.

Supply voltage - this parameter is not applicable for the LED. LEDs do not have this characteristic, so you cannot connect LEDs to a power source directly. The main thing is that the voltage from which the LED is powered (through a resistor) is higher than the direct voltage drop of the LED (the forward voltage drop is indicated in the characteristics instead of the supply voltage and for conventional indicator LEDs it ranges on average from 1.8 to 3.6 volts).
The voltage indicated on the LED packaging is not the supply voltage. This is the amount of voltage drop across the LED. This value is necessary to calculate the remaining voltage that has not “dropped” on the LED, which takes part in the formula for calculating the resistance of the current-limiting resistor, since it is this that needs to be adjusted.
A change in the supply voltage of just one tenth of a volt for a conventional LED (from 1.9 to 2 volts) will cause a fifty percent increase in the current flowing through the LED (from 20 to 30 milliamps).

For each LED of the same rating, the voltage suitable for it may be different. By switching on several LEDs of the same rating in parallel and connecting them to a voltage of, for example, 2 volts, we risk, due to the variation in characteristics, quickly burning some copies and under-illuminating others. Therefore, when connecting an LED, it is necessary to monitor not the voltage, but the current.

The current value for the LED is the main parameter, and is usually 10 or 20 milliamps. It doesn't matter what the tension is. The main thing is that the current flowing in the LED circuit corresponds to the nominal value for the LED. And the current is regulated by a resistor connected in series, the value of which is calculated by the formula:

R
Upit— power supply voltage in volts.
Upfall— direct voltage drop across the LED in volts (indicated in the specifications and usually around 2 volts). When several LEDs are connected in series, the voltage drops add up.
I— maximum forward current of the LED in amperes (indicated in the specifications and is usually either 10 or 20 milliamps, i.e. 0.01 or 0.02 amperes). When several LEDs are connected in series, the forward current does not increase.
0,75 — reliability coefficient for the LED.

We should also not forget about the power of the resistor. Power can be calculated using the formula:

P— resistor power in watts.
Upit— effective (effective, root-mean-square) voltage of the power source in volts.
Upfall— direct voltage drop across the LED in volts (indicated in the specifications and usually around 2 volts). When several LEDs are connected in series, the voltage drops add up. .
R— resistor resistance in ohms.

Calculation of the current-limiting resistor and its power for one LED

Typical LED Characteristics

Typical parameters of a white indicator LED: current 20 mA, voltage 3.2 V. Thus, its power is 0.06 W.

Also classified as low-power are surface-mounted LEDs (SMD). They illuminate the buttons on your cell phone, the screen of your monitor if it is LED-backlit, they are used to make decorative LED strips on a self-adhesive base, and much more. There are two most common types: SMD 3528 and SMD 5050. The first contain the same crystal as indicator LEDs with leads, that is, its power is 0.06 W. But the second one has three such crystals, so it can no longer be called an LED - it’s an LED assembly. It is common to call SMD 5050 LEDs, but this is not entirely correct. These are assemblies. Their total power is, respectively, 0.2 W.
The operating voltage of an LED depends on the semiconductor material from which it is made; accordingly, there is a relationship between the color of the LED and its operating voltage.

Table of LED voltage drop depending on color

By the magnitude of the voltage drop when testing LEDs with a multimeter, you can determine the approximate color of the LED glow according to the table.

Serial and parallel connection of LEDs

When connecting LEDs in series, the resistance of the limiting resistor is calculated in the same way as with one LED, simply the voltage drops of all LEDs are added together according to the formula:

When connecting LEDs in series, it is important to know that all LEDs used in the garland must be of the same brand. This statement should be taken not as a rule, but as a law.

To find out what is the maximum number of LEDs that can be used in a garland, you should use the formula

* Nmax – maximum permissible number of LEDs in a garland
* Upit – Voltage of the power source, such as a battery or accumulator. In volts.
* Upr - Direct voltage of the LED taken from its passport characteristics (usually ranges from 2 to 4 volts). In volts.
* With changes in temperature and aging of the LED, Upr may increase. Coeff. 1.5 gives a margin for such a case.

With this calculation, “N” can have a fractional form, for example 5.8. Naturally, you cannot use 5.8 LEDs, so you should discard the fractional part of the number, leaving only the whole number, that is, 5.

The limiting resistor for sequential switching of LEDs is calculated in exactly the same way as for single switching. But in the formulas one more variable “N” is added - the number of LEDs in the garland. It is very important that the number of LEDs in the garland is less than or equal to “Nmax” - the maximum allowable number of LEDs. In general, the following condition must be met: N =

All other calculations are carried out in the same way as calculating a resistor when the LED is turned on individually.

If the power supply voltage is not enough even for two LEDs connected in series, then each LED must have its own limiting resistor.

Parallel connection of LEDs with a common resistor is a bad solution. As a rule, LEDs have a range of parameters, each requiring slightly different voltages, which makes such a connection practically unworkable. One of the diodes will glow brighter and take on more current until it fails. This connection greatly accelerates the natural degradation of the LED crystal. If LEDs are connected in parallel, each LED must have its own limiting resistor.

A series connection of LEDs is also preferable from the point of view of economical consumption of the power source: the entire serial chain consumes exactly as much current as one LED. And when they are connected in parallel, the current is as many times greater as the number of parallel LEDs we have.

Calculating the limiting resistor for series-connected LEDs is as simple as for a single one. We simply sum up the voltage of all the LEDs, subtract the resulting sum from the voltage of the power supply (this will be the voltage drop across the resistor) and divide by the current of the LEDs (usually 15 - 20 mA).

What if we have a lot of LEDs, several dozen, and the power supply does not allow connecting them all in series (there is not enough voltage)? Then we determine, based on the voltage of the power source, how many maximum LEDs we can connect in series. For example, for 12 volts, these are 5 two-volt LEDs. Why not 6? But something must also drop at the limiting resistor. Here we take the remaining 2 volts (12 - 5x2) for calculation. For a current of 15 mA, the resistance will be 2/0.015 = 133 Ohms. The closest standard is 150 Ohms. But we can now connect as many of these chains of five LEDs and a resistor each as we like. This method is called a parallel-series connection.

If there are LEDs of different brands, then we combine them in such a way that in each branch there are LEDs of only ONE type (or with the same operating current). In this case, it is not necessary to maintain the same voltages, because we calculate our own resistance for each branch.

Next, we will consider a stabilized circuit for switching on LEDs. Let's touch on the manufacture of a current stabilizer. There is a KR142EN12 microcircuit (a foreign analogue of LM317), which allows you to build a very simple current stabilizer. To connect an LED (see figure), the resistance value is calculated as R = 1.2 / I (1.2 is the voltage drop in the stabilizer) That is, at a current of 20 mA, R = 1.2 / 0.02 = 60 Ohms. The stabilizers are designed for a maximum voltage of 35 volts. It’s better not to overextend them and supply a maximum of 20 volts. With this switching on, for example, a white LED of 3.3 volts, it is possible to supply a voltage to the stabilizer from 4.5 to 20 volts, while the current on the LED will correspond to a constant value of 20 mA. With a voltage of 20V, we find that 5 white LEDs can be connected in series to such a stabilizer, without worrying about the voltage on each of them, the current in the circuit will flow 20mA (the excess voltage will be extinguished at the stabilizer).

Important! A device with a large number of LEDs carries a lot of current. It is strictly forbidden to connect such a device to an active power source. In this case, a spark occurs at the connection point, which leads to the appearance of a large current pulse in the circuit. This pulse disables LEDs (especially blue and white). If the LEDs operate in a dynamic mode (constantly turning on, off and blinking) and this mode is based on the use of a relay, then a spark should be prevented from occurring at the relay contacts.

Each chain should be assembled from LEDs of the same parameters and from the same manufacturer.
Also important! Changing the ambient temperature affects the current flow through the crystal. Therefore, it is advisable to manufacture the device so that the current flowing through the LED is not 20 mA, but 17-18 mA. The loss of brightness will be insignificant, but a long service life will be ensured.

How to power an LED from a 220 V network.

It would seem that everything is simple: we put a resistor in series, and that’s it. But you need to remember one important characteristic of the LED: the maximum allowable reverse voltage. For most LEDs it is about 20 volts. And when you connect it to the network with reverse polarity (the current is alternating, half a cycle goes in one direction, and the second half in the opposite direction), the full amplitude voltage of the network will be applied to it - 315 volts! Where does this figure come from? 220 V is the effective voltage, but the amplitude is (root of 2) = 1.41 times greater.
Therefore, in order to save the LED, you need to place a diode in series with it, which will not allow reverse voltage to pass through to it.

Another option for connecting an LED to a 220V power supply:

Or put two LEDs back-to-back.

The option of power supply from the mains with a quenching resistor is not the most optimal: significant power will be released through the resistor. Indeed, if we use a 24 kOhm resistor (maximum current 13 mA), then the power dissipated across it will be about 3 W. You can reduce it by half by connecting a diode in series (then heat will be released only during one half-cycle). The diode must have a reverse voltage of at least 400 V. When you turn on two counter LEDs (there are even those with two crystals in one housing, usually of different colors, one crystal is red, the other is green), you can put two two-watt resistors, each with twice the resistance less.
I’ll make a reservation that by using a high-resistance resistor (for example, 200 kOhm), you can turn on the LED without a protective diode. The reverse breakdown current will be too low to cause destruction of the crystal. Of course, the brightness is very low, but for example, to illuminate a switch in the bedroom in the dark, it will be quite enough.
Due to the fact that the current in the network is alternating, you can avoid unnecessary waste of electricity on heating the air with a limiting resistor. Its role can be played by a capacitor that passes alternating current without heating up. Why this is so is a separate question, we will consider it later. Now we need to know that in order for a capacitor to pass alternating current, both half-cycles of the network must pass through it. But the LED only conducts current in one direction. This means that we place a regular diode (or a second LED) counter-parallel to the LED, and it will skip the second half-cycle.

But now we have disconnected our circuit from the network. There is some voltage left on the capacitor (up to the full amplitude, if we remember, equal to 315 V). To avoid accidental electric shock, we will provide a high-value discharge resistor parallel to the capacitor (so that during normal operation a small current flows through it without causing it to heat up), which, when disconnected from the network, will discharge the capacitor in a fraction of a second. And to protect against pulsed charging current, we will also install a low-resistance resistor. It will also play the role of a fuse, instantly burning out in the event of an accidental breakdown of the capacitor (nothing lasts forever, and this also happens).

The capacitor must be for a voltage of at least 400 volts, or special for alternating current circuits with a voltage of at least 250 volts.
What if we want to make an LED light bulb from several LEDs? We turn them all on in series; one counter diode is enough for all of them.

The diode must be designed for a current no less than the current through the LEDs, and the reverse voltage must be no less than the sum of the voltage across the LEDs. Better yet, take an even number of LEDs and turn them on back-to-back.

In the figure, there are three LEDs in each chain; in fact, there may be more than a dozen of them.
How to calculate a capacitor? From the amplitude voltage of the 315V network, we subtract the sum of the voltage drop across the LEDs (for example, for three white ones this is approximately 12 volts). We get the voltage drop across the capacitor Up=303 V. The capacity in microfarads will be equal to (4.45*I)/Up, where I is the required current through the LEDs in milliamps. In our case, for 20 mA the capacitance will be (4.45*20)/303 = 89/303 ~= 0.3 µF. You can place two 0.15 µF (150 nF) capacitors in parallel.

The most common mistakes when connecting LEDs

1. Connect the LED directly to the power source without a current limiter (resistor or special driver chip). Discussed above. The LED quickly fails due to poorly controlled current.

2. Connecting LEDs connected in parallel to a common resistor. Firstly, due to the possible scatter of parameters, the LEDs will light up with different brightness. Secondly, and more importantly, if one of the LEDs fails, the current of the second will double, and it may also burn out. If you use one resistor, it is more advisable to connect the LEDs in series. Then, when calculating the resistor, we leave the current the same (for example, 10 mA), and add up the forward voltage drop of the LEDs (for example, 1.8 V + 2.1 V = 3.9 V).

3. Switching on LEDs in series, designed for different currents. In this case, one of the LEDs will either wear out or glow dimly, depending on the current setting of the limiting resistor.

4. Installation of an insufficient resistance resistor. As a result, the current flowing through the LED is too high. Since part of the energy is converted into heat due to defects in the crystal lattice, it becomes too much at high currents. The crystal overheats, as a result of which its service life is significantly reduced. With an even greater increase in current due to heating of the pn-junction region, the internal quantum efficiency decreases, the brightness of the LED drops (this is especially noticeable for red LEDs) and the crystal begins to catastrophically collapse.

5. Connecting the LED to an alternating current network (eg 220 V) without taking measures to limit the reverse voltage. For most LEDs, the maximum permissible reverse voltage is about 2 volts, while the reverse half-cycle voltage when the LED is locked creates a voltage drop across it equal to the supply voltage. There are many different schemes that eliminate the destructive effects of reverse voltage. The simplest one is discussed above.

6. Installation of an insufficient power resistor. As a result, the resistor becomes very hot and begins to melt the insulation of the wires touching it. Then the paint burns on it, and eventually it collapses under the influence of high temperature. A resistor can safely dissipate no more than the power for which it is designed.

Flashing LEDs

A flashing LED (MSD) is an LED with a built-in integrated pulse generator with a flash frequency of 1.5 -3 Hz.
Despite its compact size, the flashing LED includes a semiconductor generator chip and some additional elements. It is also worth noting that the flashing LED is quite universal - the supply voltage of such an LED can range from 3 to 14 volts for high-voltage ones, and from 1.8 to 5 volts for low-voltage units.

Distinctive qualities of flashing LEDs:

Small sizes
Compact light signaling device
Wide supply voltage range (up to 14 volts)
Different emission color.

Some versions of flashing LEDs may have several (usually 3) multi-colored LEDs built in with different flash frequencies.
The use of flashing LEDs is justified in compact devices where high demands are placed on the dimensions of radio elements and power supply - flashing LEDs are very economical, since the electronic circuit of the MSD is made on MOS structures. A flashing LED can easily replace an entire functional unit.

The conventional graphic designation of a flashing LED on circuit diagrams is no different from the designation of a conventional LED, except that the arrow lines are dotted and symbolize the flashing properties of the LED.

If you look through the transparent body of the flashing LED, you will notice that it consists of two parts. A light-emitting diode crystal is placed on the base of the cathode (negative terminal).
The generator chip is located on the base of the anode terminal.
Three gold wire jumpers connect all parts of this combined device.

It is easy to distinguish an MSD from a regular LED by its appearance, looking at its body in the light. Inside the MSD there are two substrates of approximately the same size. On the first of them there is a crystalline cube of a light emitter made of a rare earth alloy.
To increase the luminous flux, focus and shape the radiation pattern, a parabolic aluminum reflector (2) is used. In an MSD it is slightly smaller in diameter than in a conventional LED, since the second part of the housing is occupied by a substrate with an integrated circuit (3).
Electrically, both substrates are connected to each other by two gold wire jumpers (4). The MSD housing (5) is made of matte light-diffusing plastic or transparent plastic.
The emitter in the MSD is not located on the axis of symmetry of the housing, so to ensure uniform illumination, a monolithic colored diffuse light guide is most often used. A transparent body is found only in large-diameter MSDs with a narrow radiation pattern.

The generator chip consists of a high-frequency master oscillator - it operates constantly; its frequency, according to various estimates, fluctuates around 100 kHz. A logic gate divider works together with the RF generator, which divides the high frequency to a value of 1.5-3 Hz. The use of a high-frequency generator in conjunction with a frequency divider is due to the fact that the implementation of a low-frequency generator requires the use of a capacitor with a large capacity for the timing circuit.

To bring the high frequency to a value of 1-3 Hz, dividers are used on logic elements, which are easy to place on a small area of ​​the semiconductor chip.
In addition to the master RF oscillator and divider, an electronic switch and a protective diode are made on the semiconductor substrate. Flashing LEDs, designed for a supply voltage of 3-12 volts, also have a built-in limiting resistor. Low-voltage MSDs do not have a limiting resistor. A protective diode is necessary to prevent failure of the microcircuit when the power supply is reversed.

For reliable and long-term operation of high-voltage MSDs, it is advisable to limit the supply voltage to 9 volts. As the voltage increases, the power dissipation of the MSD increases, and, consequently, the heating of the semiconductor crystal increases. Over time, excessive heat can cause the flashing LED to rapidly degrade.

You can safely check the serviceability of a flashing LED using a 4.5-volt battery and a 51-ohm resistor connected in series with the LED, with a power of at least 0.25 W.

The serviceability of the IR diode can be checked using a cell phone camera.
We turn on the camera in shooting mode, catch the diode on the device (for example, a remote control) in the frame, press the buttons on the remote control, the working IR diode should flash in this case.

In conclusion, you should pay attention to such issues as soldering and mounting of LEDs. These are also very important issues that affect their viability.
LEDs and microcircuits are afraid of static, incorrect connection and overheating; soldering of these parts should be as fast as possible. You should use a low-power soldering iron with a tip temperature of no more than 260 degrees and soldering should take no more than 3-5 seconds (manufacturer’s recommendations). It would be a good idea to use medical tweezers when soldering. The LED is taken with tweezers higher to the body, which provides additional heat removal from the crystal during soldering.
The LED legs should be bent with a small radius (so that they do not break). As a result of the intricate bends, the legs at the base of the case must remain in the factory position and must be parallel and not stressed (otherwise the crystal will get tired and fall off the legs).

If it were unprofitable for humanity to use LEDs, then only a limited circle of scientists would know about them. But the source with a fundamentally new type of radiation turned out to be very effective. Over time, small crystals began to be combined several times in one case, and they also learned to grow super crystals of increased sizes. The result is ultra-bright LEDs, or, as they are also called, super-bright LEDs, with a wide range of application possibilities.

The elementary LED itself is designed for a voltage of more than 3-5 Volts. Its characteristics make it possible to use such an element for display purposes and for decorative lighting. However, scientists managed to develop more powerful devices using a number of tricks. This is how super-bright 12-volt super LEDs were born. Using a driver, a 12 Volt device can be connected to a higher voltage, including a 220 Volt network.

Pulse brightness change

The main advantage of an ultra-bright 12-volt super LED is its low energy consumption and at the same time bright light. An additional advantage is a controlled change in the brightness of the LEDs, for which a controller is used. It turns out that a device that uses ultra-bright LEDs can reduce or increase the intensity of its radiation.

To control the brightness of LEDs, pulse width modulation is used. With this method, you can reduce the brightness by periodically turning off the light bulb. The lamp pulsates, and the pulsation parameters will determine the intensity of its glow.

This operating principle allows you to expand the capabilities of high-brightness LEDs. As a result, we get functional:

• flashlights;
• car lights;
• light alarm;
• home lamps.

Note that the alarm uses a flashing LED of 5, 12 and even 14 volts, which helps to draw attention to the display cases, counter or cash register window. Low voltage devices are also used. A flashing LED is designed slightly differently than a regular indicator light. A pulse generator chip is placed in the housing where the crystal is located.

Most often, super-bright 12-volt LEDs replace halogen lamps, which provide directional light. That is why, when producing lamps using LEDs, they are made with a standard base E14, GU10 and some others.

Important Features

All super bright sources have the same light characteristics as conventional LEDs:

• light flow;
• brightness;
• light output;
• illumination

When installing a 12-volt LED lamp on a particular device, you need to understand that its effectiveness depends on the wavelength of the radiation or, more simply, on the color. Here is a table showing the dependency.

But by studying these characteristics, not every person will be able to understand which device is right for him. It is much easier to decide by looking at the electrical parameters: voltage, maximum forward current, device power.

In addition to this, there are other characteristics. Super-bright LEDs can be created on the basis of a single crystal or be multi-chip. Characteristics such as wavelength and color temperature are responsible for the color of the glow. Important parameters are the beam angle, body size and the number of LEDs in one lamp.

The development of new models has led to the appearance of another distinctive feature - the shape of the case. A popular package for ultra-bright 12-volt LEDs is the “piranha”, which has four terminals. There are also dual terminal and surface mount models available.

Each device model has its own parameter table, by looking into which you can find out the operating features of this device.

A few caveats

The main problem in the production of super-bright LEDs is the problem of heat dissipation. The LED must not overheat, otherwise the light intensity will irreversibly decrease. Super-bright, high-power devices are especially susceptible to overheating, so when installing them yourself, it is necessary to ensure their cooling using a radiator.

Pay special attention to the electrical parameters, avoiding connecting to a voltage that is higher than that specified in the instructions, and providing only the permissible current. Thus, super-bright sources will be able to shine for as long as possible.

Handle the copper leads with care, as kinking or severe deformation will cause the signal strength to change.

The first thing you must understand before you begin the replacement procedure: Light-emitting diode- this is not a light bulb. Be careful and attentive when repairing electrical equipment auto as a result of your wrong actions is an unpleasant thing. This, however, concerns not only LEDs, but also any actions with electrical wiring, be it installing an amplifier or additional signals. But, nevertheless, it is not the gods who burn the pots, there is nothing complicated in such a replacement, any person with straight hands is able to do it on his own.

The main points that we need to learn:

1.Voltage car on-board network. Typically this is 12 - 13 V when the engine is off and 13 - 14.5 V when the engine is running.

2. Typical LED Supply Voltage– 3.5 V. Depending on the color this could be: for yellow and red LEDs- 2 - 2.5 v.; for blue, green, white - 3-3.8 in. Typical Low Power LED Current– 20 mA, powerful– 350 mA.
3. Not everything LEDs, Unlike light bulbs, illuminate the space around them. This must be taken into account when replacing indicator lamps, For example, in the dashboard. When purchasing, you should pay attention to lens type or, if possible, ask the seller. Narrowly targeted LEDs have a small lens at the end. In general, try to check this when purchasing, or even better, buy and try several different ones.
4. U LED, like battery, There is plus And minus. The minus is called the cathode, the plus is the anode; in the diagrams they are depicted as follows:

It should be clear to you that it’s easy to take and turn on

LED in the car's on-board network- this meansguaranteed to burn it.

Want to make sure? Take and connect any cheap Light-emitting diode directly to the on-board network. From a lighter, for example. It will shine beautifully and smoke :) But you will imagine what the process looks like. Expensive LEDs they burn out in the same way, so it’s better to train on cheap ones.

Connecting LEDs

1. On sale for sale LED panels, so-called clusters, they are designed for food 12v. You can simply connect them to the on-board network and enjoy the beautiful lights. But there is an unpleasant feature - when the engine speed changes, the brightness of the glow will change LEDs V clusters. Slightly, but noticeable to the eye. In addition, in fact, they light normally at a voltage of about 12.5 V, so if you have low voltage in the on-board network, light clusters will be dim. Structurally, the cluster consists of a chain LEDs And resistor. For every three LEDs there is a resistor that absorbs excess voltage. The LED strip is designed in exactly the same way, so if you need to cut off a piece, look at the strip, there are places on it where you can cut it. Usually these are the same three LEDs and a resistor... You can’t cut anywhere :)

2. Turn on the LEDs in series, in a chain, that is, make a homemade cluster. That is, connect the required amount to each other, and the remaining two outputs to the on-board network. Let's make a reservation that we are talking about white LEDs. LEDs of different colors have different voltages. It is easy to calculate that for 12-14 V you will need 3 LED. In total they will give 3.5 x 3 = 10.5 v. As mentioned above, LED there is a plus and a minus. A connection in series is when the plus of one is connected to the minus of the next, and so on until the end of the chain.

But you still can’t connect them directly; you need to turn them on in series with your chain excess voltage suppressing resistor(resistance) - nominally approximately 100-150 Ohms, power 0.5 W. Resistors Sold at any amateur radio store.

This method suffers from the same drawback as the previous one - a change in the intensity of the glow LEDs when changing speed. Small, but unpleasant. However, using this scheme you can connect any number LEDs, collecting them in chains of 3 pieces. With resistor and including in parallel. In parallel, this means collecting several identical chains, connecting the plus of each chain with the plus of another chain, and the minus with the minus. In general, the resistor value is calculated using Ohm's law. But if you are not comfortable with formulas, use a simple rule: if you include 1 Light-emitting diode- a resistor needs 500 Ohms, if two - 300 Ohms, three LED- 150 Ohm. In this case, you don’t have to read further. :) But after spending half an hour studying a simple formula, you will learn to select the values ​​correctly resistors, which means yours LEDs will shine for a long time and correctly. I can assure you that you don’t need to be an academician, I will try to explain it in detail and clearly. You will need:

2. Ohm's law for a section of an electrical circuit, that is, for your LED And resistor. R=U/I. Where R is the resistance of the resistor, U is the voltage that needs to be extinguished, I is the current in the circuit. That is, to get damping resistor resistance, need to be divided voltage, which needs to be extinguished, for the current that needs to be received.

Let's look at an example. We have a simple white LED which we need connect to the vehicle's on-board network. The supply voltage is LED approximately 3.5 V, current - 20 mA.

1. We measure voltage at the point where we are going to connect the LED. The fact is that the voltage in the on-board network is different. There may be 13 volts on the battery, 13.5 on the cigarette lighter, etc. Therefore, decide in advance where you will connect. Turn the device into voltage measurement mode and take measurements. Let's say this is the 13th century. Write it down on a piece of paper.

2. Subtract from 13c LED supply voltage(3.5v). We get 9.5 v. The current is inserted into the formula in amperes, one ampere is 1000 milliamps, that is, in our case, 20 mA - 0.02 A. Using the formula, we calculate the resistance:

9.5/0.02=475 Ohm.

To prevent the resistor from heating up during operation, we calculate its power. To do this, you need to multiply the voltage that the resistor extinguishes - 9.5 volts, by the current that passes through it - 0.02 amperes. 9.5x0.02= 0.19 watts. It is better to take a resistor with a reserve - 0.5-1 watt.

That is, we need to tell the seller in the radio store “I need a 475 Ohm 0.5 or one watt resistor.” You can use a higher denomination, just shine LEDs will be dimmer. Smaller - it will be brighter, but he may not like it.

Having purchased what you are looking for, we connect and rejoice :) To finally make sure that the calculations are correct, you can measure the current in the circuit. To do this, you need to turn on the multimeter in current measurement mode (see the instructions for the device) in the gap between resistor And LED. If the instructions are lost, no problem. Set the dial to the “10A” label, and switch the red probe into the socket labeled “10A”.

It should read 20 milliamps or less. U resistors And LEDs there is a spread of parameters, so the current may differ in both directions, but only slightly. If the value is from 15 to 23 mA, it is normal. The higher the current, the brighter the LED shines, but the shorter its service life. Therefore, for ordinary LEDs It is not recommended to set the current above 20 mA, optimally 18 mA. The best way to select the desired resistance is to use variable resistor. But this is more difficult :)

The above information will allow you to connect any number of low-power and high-power LEDs, it is enough to know them operating voltage and current and substitute them into the formula.
It can be very useful to connect in parallel LED a regular diode of any type in reverse polarity, that is, the cathode of the diode to the anode LED. This will protect your Light-emitting diode from reverse polarity voltage. This is especially true for domestic cars of venerable age.

For the most inquisitive :) - the first LED driver for cars

Further information is intended for advanced amateurs who have already mastered Ohm's law. There is no limit to perfection, and it’s not enough for you to just light up LEDs- I want them to shine evenly, regardless of engine speed.

The most correct inclusion LEDs– through a current stabilizer. Light-emitting diode is a semiconductor device that is powered by current rather than voltage. Therefore, if you stabilize and limit the current flowing through it, you can connect at least a kilovolt, Light-emitting diode it will shine normally. And how long depends on the operating mode Light-emitting diode will shine without losing brightness. To stabilize the current, devices called drivers. The simplest driver is a circuit on a stabilizer chip LM317. The main advantage of this chip for beginners is that it is very difficult to burn :)

Are you scared? Nothing :) In essence, two parts are required - the microcircuit itself - three-terminal voltage stabilizer, which we will turn on in current stabilization mode, and resistor. In order not to go into theory, the steps are as follows - we purchase a variable resistor with a resistance of 0.5 kOhm. This is a thing with three terminals and a twist. Like the microcircuit, it is sold in the same “Radio Amateur” for ridiculous money. You can even pick it out of an unnecessary household appliance. We solder the wires to the middle pin and one of the outer ones, no matter which one. Turn on the multimeter in resistance measurement mode. We connect the device to the wires and measure the resistance of the resistor. By rotating the rod we achieve the maximum reading, that is, 500 Ohms (or so). This is so as not to burn Light-emitting diode when the resistor resistance is too low.

We assemble the chain. Attention! Please check the connections carefully before connecting? Have you checked? Exactly?

We turn on the device in current measurement mode. By rotating the variable resistor slider, we achieve a device reading of 20 mA. We disconnect the circuit, measure the resistance of the resistor and solder in a regular resistor with the same resistance instead. Voila! You've just collected your first led driver:) It has a maximum current limitation of 1-1.5 A, so when connecting a large number of LEDs: first, use a higher power resistor. Secondly, touch the chip. If it is hot, it makes sense to attach it to the radiator. Do not forget that the car body has electrical contact with the negative side of the battery, and the chip substrate (body) has electrical contact with its second leg. Therefore, attaching it to the body without an insulating gasket is a bad idea. Another nuance is that the microcircuit itself reduces the maximum voltage that can be applied to the LED by two to three volts. Therefore, you will not get more than 11-12 volts with such a driver. But it’s simple and will give you the first idea about the correct connection of LEDs in a car :) By the way, on the same chip + a couple of parts you can assemble an adjustable power supply of 1.5-30 V, which can be very useful in a car. There are many connection schemes on the Internet.
In general, if everything worked out for you, welcome to the fascinating world of radio electronics, because you are unlikely to stop now...

Maybe now you’ll even collect

(With) Yuri Ruban, led22.ru. Questions and criticism are welcome in the section

Energy-saving technologies and equipment are in demand and popular. One such device is an LED lamp. It uses LEDs as a light source, which are combined into one circuit. This light bulb is used in lighting fixtures to decorate the illumination of buildings and structures, in spotlights that are mounted on suspended or suspended ceiling structures.

Design of LED lamps

LED lamps are designed for a voltage of 12 V and, accordingly, the design of the device differs from its fluorescent counterparts or those that use an incandescent filament. Structurally, it is made of the following main components:

• Glass flask. It can be made of transparent or frosted glass and have a spherical or flat shape. The dome design increases the light dispersion angle to 270°. Models of light bulbs with a flat glass surface are used in spotlights to illuminate the interior or divide the area into separate zones. Lighting angle 30 – 60°.
• LEDs. Light sources are connected in series into one connection circuit, which increases the light output of the device.
• Radiator. It is a metal plate made of aluminum alloy. It is designed to remove the heat emitted by the LEDs.
• Frame. It is made of high-strength plastic, which is a dielectric and performs protective functions against electric shock when installing or dismantling the light source.
• Driver. Designed to stabilize voltage and convert current from alternating to direct.
• Base. It can be manufactured for different types of cartridges: standard design E27 and E14 or G4, G13, GU10 and so on.

Depending on the amount of light emitted by one diode and the number, the brightness of the LED lamp is determined. The average illumination value is calculated from the ratio of 1 Lm (Lumen - a unit of measurement of the brightness of a luminous flux) per 100 W.

Advantages and disadvantages of 12V lighting

To switch to lighting fixtures that connect to a low-voltage power source, you should study their advantages and disadvantages. Among the advantages are the following:

• Safety. The use of LED lamps in 12V luminaires increases the level of protection and eliminates the possibility of electric shock.
• Fire safety. Low voltage wiring cannot be a source of ignition or cause a fire. Therefore, the wires do not need additional protection; they are not placed in corrugated sleeves.
• Versatility. An electric current whose voltage does not exceed 12 V is considered conditionally safe and cannot cause serious harm to a person. In this regard, these lamps can be used in rooms with normal conditions and increased danger. For example, in lamps for a sauna, cellar, bathroom, kitchen, bedroom, etc.
• Saving. When using this light source to illuminate a room, it reduces energy consumption and, accordingly, the cost of money to pay bills.
• Environmental friendliness. The design does not use materials that, during operation of the device, emit substances harmful to human or animal health.
• Reliability. The lamps are highly resistant to mechanical damage: scratches, chips, dents, etc.

Despite all the advantages, the light source also has its disadvantages. The disadvantages of LED lamps designed for 12V include:

• An additional device is required - a power supply unit (PSU). The presence of a driver that stabilizes and reduces the network voltage from 220 to 12 V complicates the wiring. It has its own efficiency, which reduces the efficiency of lighting and due to it, an additional weak link appears in the circuit, which can fail.
• Glow brightness. The luminous flux power of a lamp connected to a low-voltage network is affected by the voltage drop. This occurs due to high current consumption. Therefore, the length of the conductor from the transformer to the first and last light source must be the same, an error of 2 - 3% is allowed. Otherwise, the last lamp will shine dimmer than the first.

Types of LED lamps

Light sources are classified according to several criteria:

• Base type. Available in traditional versions with standard sizes: E14, E27, E40. Baseless lamp models are also produced: G4, G5, G9, etc.
• Glow temperature. There are three types of emitted light: soft - temperature from 2500 to 2700 °K, white - 3800 - 4500 °K and cold light temperature more than 5000 °K
• LED type. Depending on the power and purpose of the lamp, LEDs have different configurations, which are determined by the type of crystal. It can have legs for connection or be mounted directly into the board.

Power supply for 12V LED lamps

Power supplies are selected depending on the purpose of the LED lamps.

They are divided into the following types:

• Sealed. Used for installing lamps in the bathroom, sauna, and street lighting.
• Leaky. Designed for indoor installation with normal humidity levels.
• With active cooling. It is equipped with a fan, which increases power and reduces size.
• Passive cooling. A radiator is used to remove heat. The advantage is silent operation. Disadvantage: power is limited by the size of the device.

Also, power supplies are selected according to their main characteristics:

• Power. It is calculated by adding the entire connected load plus a power reserve of 10 - 15% to prevent operation in overload mode.
• Output current. Depends on the number of connected lamps. If the load power and the “cosine phi” of the lamps are known, then the current can be calculated using the formula: total power of the lamps / 12 / cos φ. The value of the parameter also determines the cross-sectional area of ​​the conductors connecting the power supply and lamps.
• Output voltage. For our case it is 12V.

When connecting 12V LED lamps to a 220V electrical line, they must be powered by a driver or power supply.

Technical progress in the field of energy-saving technologies contributes to the constant development and improvement of the technical and operational characteristics of LED lamps.

Video on the topic