Super bright 3 volt LEDs for flashlights. Characteristics of LEDs for flashlights. Repair and increase in power. Important light parameter: brightness bin or light temperature

LED operation is based on semiconductor knowledge and practice. They have been known to mankind for almost half a century. At the same time, everything starting materials We have been familiar with the manufacture of such lighting fixtures for more than 20 years. However, it was only recently that we succeeded in connecting them correctly and obtaining impressive LED characteristics. This lighting represents an innovative breakthrough, making diodes quite efficient and environmentally friendly. It is believed that such accessories are much more economical than classic incandescent lamps. They can be used in various fields human life not only because of ease of use, but also due to the desired glow temperature.

Characteristics

In order to understand the principle of operation of the devices, you need to know the following characteristics of LEDs:

1. Luminous flux. This parameter is measured in lumens (Lm) and shows the amount of light that the lamp produces. The higher this indicator is, the brighter it will shine.
2. Power consumption is measured in Watts (W). The smaller this parameter, the more economical the energy consumption.
3. Light output, its unit of measurement is considered to be Lm/W. It is central to the work and efficiency of everything. lighting fixture.
4. Radiation direction diagram. Parameter of the luminous intensity curve, due to which the fluxes emitted by the diodes are distributed.
5. Color temperature (shades of white light). It is measured in degrees Kelvin in the permissible range from 2700 to 7000 K. The shade of a warm color is considered the most favorable for the eyes, which varies up to 4000 K, and all indicators that are higher are usually referred to as “cool white”. Most often, lamps with warm light are much more expensive than those with cold light, since this is directly related to the features of their production.
6.Color rendering index. This value shows how truthfully the color of an object illuminated by the selected lamps will be displayed. The higher this parameter, the more truthfully the shade of the original object is conveyed.
7. Performance of lighting devices. The most correct decision is to choose branded manufacturers, since such companies can provide more accurate technical characteristics of LEDs, thanks to which the device will last the stated operating time. Also, such lamps provide protection against voltage surges and overheating.
8. Device size. There is no need to judge the advantages and disadvantages based on the size of the crystal. It does not matter whether the LED is large or small, the most important thing is its power.

Considering these characteristics of LEDs, you can choose exactly the device that will give the maximum effect from its intended use.

Quality indicators

The quality indicators of an LED product can be judged based on the following criteria:
- manufacturer (preferably products from well-known companies that publish open data on the reliability of their devices);
- the use of a specially designed design and shape for the fastest possible heat removal, regulating the temperature during operation of the chip;
- optical (lighting) specifications of the LED lamp, which can be obtained from an independent laboratory or manufacturer;
- high-quality guarantees;
- results of long-term tests of the functioning of devices.

White varieties

Most often in everyday life, for decoration and lighting, white LEDs are used, the characteristics of which depend on their tone.

Warm white light: its color temperature is 2700 K and it has a slight yellowish tint, similar to the flame that a candle emits. This shade is typical for incandescent lamps; it calms and relaxes. It is important to note that using a matte or transparent shade will change the shade to a softer or richer one. This type of light is not the main one, but it is perfect for additional and decorative lighting and will be ideal for installation in bedrooms. Thanks to it, you can create harmony and homely warmth in the room.
Natural white light: Its color temperature is 4200K, it is the most popular and most commonly used. Suitable for use as the main source of lighting for both commercial and domestic premises. Can be used on all types of surfaces, such as a kitchen countertop or a desk in an office. Like warm light, natural has several shades. Fixtures and lamps with matte dispersion will have a completely different saturation spectrum than devices with a transparent bulb. It helps produce more accurate and directional light than matte, through which soft highlights of an unobtrusive shade are emitted.
Cool white light: its color temperature is 6000 K. It has a peculiar bluish tint. This tone is very bright and is most often used for offices and also as local lighting. It has become quite widespread in parking lots, entrances, local area, as well as in parks, alleys and squares. Often installed to illuminate street advertisements, commercial signs, and more.

Types of LEDs

There are a variety of LEDs, the parameters and characteristics of which completely depend on their types:

1.Blinking: used in indicators to attract attention. This type is practically no different from the usual ones, however, for its production a built-in multivibrator circuit is used, which flickers with a break of 1 second. The main types of such diodes distribute single-color light rays; more complex ones in their characteristics can flash in several shades alternately or simultaneously, thanks to the RGB parameter.

2. Multi-color blinking LEDs, the characteristics of which are quite diverse and can be represented in two different crystals, working one towards the other, therefore, when the first one lights up, the second one goes out completely. With the help of a current that moves in the initial direction, one color appears, and in the opposite direction another color appears. Thanks to this type of work, a third color is formed, since the two main ones are mixed.

3.Tri-color LEDs, the parameters and characteristics of which consist in the presence of several light-emitting diodes, not connected to each other, but combined in one housing. They work separately, they can light up at the same time, but their controls remain completely different.

4. Light-emitting RGB diodes with blue, red and green elements that use a four-wire connection and a single common cathode or an anode.

5. Monochrome displays with seven segments, as well as using starburst format. Such screens show all the numbers, and some even a certain set of letters. Using Starburst allows all symbols to be displayed.

Alphanumeric and numeric displays, which were quite common in the 80s, became less popular after the advent of LCD monitors.

Advantages of LED lighting

As a relatively new technology, LEDs are generally superior to many lighting sources in terms of light quality, energy efficiency, environmental friendliness and cost-effectiveness. The characteristics of LEDs are superior to those of high-incandescent lamps in almost all areas of application, but such lighting cannot yet solve all the tasks. White diodes have already proven themselves to be an excellent alternative to fluorescent tubular and high-pressure lamps. But a short amount of time still needs to pass before such technologies begin to be used in the public system.

What does the SMD marking mean?

The decoding of this indicator sounds like Surface Mounted Device, which translated into Russian means “a device that is mounted on a surface.” Such a device is a diode, and the surface in our case is the base of the tape.

Any SMD LEDs, the characteristics of which are similar to those of all other similar lamps, consist of several crystals placed in a housing with contact leads, as well as lenses that form the luminous flux. It is emitted by semiconductors and directed into a miniature optical system, which is formed by spherical reflectors, as well as the transparent body of the diode itself.

What other characteristics do SMD LEDs have? The marking, which is represented by numbers on the tape, shows the dimensions of the crystal in millimeters. The SMD-based strip bends very well in the longitudinal direction.

What does the DIP LED marking mean?

There are also LEDs on sale, the characteristics of which are very similar to SMD. According to their own technical parameters they are a cylindrical body, which is placed on the end strip. This type has good silicone protection. The numbers that are present in the marking, as well as for SMD, indicate the diameter of the diode.

To illuminate furniture, you can use such crystals, only for glass shelves. Unlike the previous tape, this type bends very well in the transverse direction.

Parameters of a high-quality LED flashlight

Today, you can buy a large number of conventional flashlights on the market, but they are being actively replaced by LED ones. This happened primarily due to the fact that the latter give much more bright light.

In order to choose the right LEDs for flashlights, the characteristics of which are very diverse, it is necessary to take into account all the basic requirements of the buyer when choosing. What you need to pay attention to is the type of beam, it can be wide or narrow. Which type to choose depends on the future application. For example, in order to be able to see objects at a distance of 30 meters, it is better to choose a flashlight with a wide beam, while models with a narrow beam can illuminate distant objects well. Most often, such lighting is provided by tactical devices used by tourists, hunters and cyclists.

Another important factor affecting the operation of the flashlight is the type of power supply. For the simplest household appliances ordinary AA or AAA batteries are used, but for strong and powerful devices this volume will not be enough. In this case, it is necessary to use lithium-ion batteries, which can operate continuously for 5 hours.

It is worth paying attention to LEDs for flashlights, the brightness characteristics of which differ from each other by no more than 40%. The quality of the selected devices is guaranteed by the presence of markings. In cases where it is absent, we can talk about an uncertified product, most often made in China.

LEDs from CREE

This company specializes in the manufacture of high-quality and bright diodes. She was one of the first to develop new white light bulbs, thereby setting a new milestone in the industry.

CREE LEDs, the characteristics of which are presented, remain competitive in their industry:

They have record luminous flux values reaching 345 lumens at a current of 1000 mA;
- thermal resistance at a low level;
- relatively wide angle of study;
- miniature, evenly distributed crystal;
- maximum current reception up to 1500 mA;
- improved silicone lens instead of glass;
- maximum crystal operating temperature 150 °C.

As you can see, such technologies are just coming into force and bring exceptional benefits from their use. Every day new discoveries are made, LED lamps become more economical and brighter, thanks to which they rightfully begin to occupy a leading place in the lighting arena.

Features of SMD 5050 tapes

LEDs in this series have a size of 5x5 mm and a luminous flux depending on color, which ranges from 2 to 8 lumens. They can also be divided according to the degree of moisture protection - IP20 and IP65, since they have two different types of coatings, namely polyurethane and silicone. The former can only be placed indoors, while the latter, accordingly, are suitable for the street, since they are not afraid of excessive humidity.

5050 LEDs, whose characteristics and properties help create bright light, consist of three crystals with different or identical diodes in one package. Multi-colored lamps are called RGB (red-green-blue), after connecting controllers, you can get a variety of colors in them.

The main technical characteristics are:

Transparent and rigid polyurethane coating;
- high-quality soldering;
- the number of LEDs per 1 meter is 60 pieces;
- cutting ratio - 3 crystals, which is 50 mm;
- width, length, height in mm 10 x 5000 x 3;
- the power supply is connected to 12V or 24V DC.

Features of SMD5730 tapes

Adopting high-efficiency 5730 LEDs, the characteristics and properties of high thermal conductivity and low resistance ensure a long service life of the device. They are vibration resistant high humidity environment and temperature changes. They are small enough, have a wide luminous angle and are perfect for any surface for installation. They can be purchased in reels and tapes.

Many people like to use 5730 LEDs, whose characteristics are suitable for use in various devices, which is very convenient for both ordinary users and designers. They are indispensable for lighting retail and office premises, where not only high energy efficiency is considered important, but also comfortable light transmission.

For those who use LEDs, markings, characteristics and properties are of no small importance. They have a number of advantages over their predecessors, namely:

Phosphor white LEDs with a nominal power of 0.5 W are distinguished by a significant service life, stable performance and high-quality performance;
- high resistance to temperature changes, vibrations and high environmental humidity;
- degradation of the luminous flux - no more than 1% for 3000 hours of operation;
- the body is made of high-quality heat-resistant polymer that can withstand up to +250 °C;
- LEDs are fully suitable for reflow soldering.

When selecting or assembling a new LED flashlight Be sure to pay attention to the LED used. If the only task of the future flashlight is to illuminate a dark entrance, then almost any bright white LED will cope with this task. Another thing is the desire to get a portable lighting device with parameters for a more complex task. In this case, the luminous flux is of particular importance, that is, the ability of the flashlight to produce a sufficiently powerful beam and illuminate a wide area of space.

Which LED brands are in the top positions, and what characteristics do their light-emitting diodes used in flashlights have?

Main characteristics

The quality of light emitted by the flashlight is controlled by the LED, which can be called, without exaggeration, the heart of the device. The stability of a flashlight's heart rate depends on many parameters, the main ones being current consumption, luminous flux and color temperature. The trendsetter is considered to be the Cree company, which produces a wide line of super-bright and powerful LEDs, including for flashlights. Modern flashlights are designed with a single LED with a power of 1, 2, or 3 W. In the one-watt version, the forward current is about 350 mA with a voltage drop of 2.8-2.9 V.

The current and voltage of a two-watt LED is about 700 mA and 3.0 V, respectively, and a similar 3 W crystal consumes approximately 1000 mA and 3.2 V. The electrical indicators given are typical for LED models of the world's leading brands.

The radiation intensity, also called luminous flux, depends on the manufacturer and family of the LED. The rated value of the luminous flux of high-power LEDs is usually measured at the maximum permissible operating current. The manufacturer of branded flashlights, along with the type of LED installed, indicates the number of lumens produced by the product.

Unfortunately, flashlight packaging often indicates inflated characteristics, including luminous flux. The reason for this is simple - any manufacturer wants to sell as much product as possible.

Luminous flux is inextricably linked with light. Modern light-emitting diodes are capable of emitting a luminous flux of up to 200 lumens per 1 watt and can be produced with any glow temperature: from yellowish warm to cool white. Lanterns with a warm white emission color (T≤3500°K) are the most pleasing to the eye, but less bright. Lighting with a neutral color temperature (T=4000-5500°K) allows you to view fine details more effectively. Cold white beam (T≥6500°K) in powerful flashlights with a long illumination range, but during prolonged operation it irritates the eyes.
Due to the impossibility of making accurate calculations, the lifespan of LEDs is calculated by extrapolation. At a temperature of 25-50 °C, their crystal service life can exceed 200 thousand hours, but this is not economically justified. Therefore, manufacturers allow the operating temperature to increase to 85°C, thus saving on cooling costs. Exceeding the threshold of 150°C leads to irreversible processes of crystal burnout and loss of brightness.

Color rendering index (CRI) – qualitative indicator, characterizing the ability of an LED to illuminate objects without distorting their real color. For LED sources lighting, including flashlights, a color rendering index of 75 CRI and above is considered good.

An important element of an LED is the lens. It sets the angle of dispersion of the light flux, and therefore determines the range of the beam. The technical characteristics of LEDs must indicate the value of the radiation angle. For each model, this parameter is individual and can vary from 20 to 240 degrees. Powerful LEDs for flashlights have an angle of 90-120° and, as a rule, are equipped with a reflector with an additional lens in the housing.

Despite the sharp leap in the development of high-power multi-chip LEDs, world leaders continue to produce less powerful LEDs. They are produced in cases not big size not exceeding 10 mm in width or diameter. The typical current value of such light-emitting diodes does not exceed 70 mA, and the luminous flux is 50 lm. Powerful flashlights based on them are gradually disappearing from store shelves due to worse technical characteristics and the need for series-parallel connection to increase brightness. Compared to one powerful crystal, the reliability of the circuit and the dispersion angle of several such elements in one package are much worse.

Separately, it is worth noting the four-pin LEDs in the P4 “SuperFlux” or “Piranha” package, which have improved technical characteristics. Piranha LEDs have two important advantages that make them in demand:

distribute the light flux more evenly;
do not require heat removal;
have low cost.

5 largest manufacturers

A portable flashlight must not only be ergonomic, but also be equipped with a reliable LED source with a high working life without loss of brightness. In order not to make a mistake with your choice, preference should be given to world-class manufacturers of LED products.

A division of the Japanese company Nichia has long held a leading position in the production of LEDs of all types. Due to the high cost of products and increasing competition from China and Taiwan, today it is becoming increasingly rare to find their LEDs in flashlights on the European market. However, the world needs Nichia as an engine of progress. After all, the developments of Japanese companies are taken as a basis by their Chinese and Taiwanese colleagues.
Powerful LEDs for flashlights from the world-famous company Cree hold the lead not only on the American continent. Standing out due to their lower cost and high quality, LEDs from Cree are available to everyone on the European continent. A rechargeable flashlight with a powerful crystal from an American brand is a reliable friend on a hike, night fishing, etc.
Philips Lumileds is a European manufacturer of wide-spectrum light-emitting diodes. The company has achieved certain progress in the construction of outdoor lighting systems of functional and architectural significance. Philips Lumileds developers take an integrated approach to building LED systems, taking into account their design, degree of protection and ease of use.
The South Korean corporation Samsung, well known in Russia, promptly financed its division to search for new LED solutions and now has a full production cycle of emitting diodes. Samsung is not limited to producing LED backlights for its own displays. Their successes have spread to other market segments: high-power LEDs (including for flashlights), ultra-bright flash elements, as well as indoor and outdoor lighting modules.
Osram Opto Semiconductors has become famous for the excellent characteristics of LEDs from the Duris series, which are distinguished by their high luminous efficiency and color rendering index. German company relied on the introduction of LED technologies into industrial sectors, focusing on the production of ready-made specialized lamps and fixtures. Osram laboratories improve the performance of light-emitting diodes not only in the visible spectrum, but also make discoveries in the IR, UV and laser directions.

Reports from scientists along with development news artificial lighting indicate continued healthy competition between large corporations. We see positive trends in the development of LED technologies in the constantly updated model range flashlights that surprise with their long-range beam, high degree of protection, ability to charge from solar energy and other know-how.

Subtleties of choice: modern types of LEDs and their characteristics

95% of new flashlight models use Cree LEDs, which are produced in different series. In a short time, this enterprising manufacturer practically eliminated all competitors from the market.

The main difference between LEDs is related to the maximum brightness and size. Of all the diversity offered, it is worth highlighting the following main series:

XP-E and XP-E2 have standard dimensions of 3.5x3.5 mm, are designed for a current of 1A and a power of 3.5W. As a rule, they are used in keychains and small models.
XP-G, XP-G2 with similar diode sizes, the power is 4.9 W, the current is 1.5 A, and the brightness is up to 490 lm. Used in small lanterns, like the previous series.
XM-L and XM-L2 with dimensions of 5x5 mm provide 10 W of power, 3A of current and 1040 lm of brightness. Such diodes in the amount of one or several pieces are used in medium and large flashlights.

LEDs, which are additionally marked with the number 2, are distinguished by the fact that they produce a brightness that is 10-20% higher.

Recently, Nichia 219 LEDs are also gaining popularity, which have practically made a breakthrough. They differ from Cree in better color rendering, which is pleasing to the eye.

Important light parameter: brightness bin or light temperature

Types of LEDs for flashlights have different glow temperatures. Be careful: the most comfortable light spectrum is selected individually, and reputable manufacturers can produce one model with different LED options different shades.

Manufacturers divide them into main groups, which are quite easy to distinguish thanks to standard labeling:

Warm White - warm colors. Such LEDs are more expensive because they produce less distortion of natural colors.
Neutral White - neutral. They are the golden mean. Like LEDs with a warm spectrum, they are optimally suited for household purposes.
Cool White - cold. As a rule, they are mounted in more budget models; they somewhat distort natural colors due to a bluish tint, however, compared to warm ones, they provide higher brightness. Used in powerful tactical and search flashlights.

LED drivers: current stabilization

In all high-quality models, the LED is powered not directly from batteries, but through a stabilizing device - the driver. In addition to saving battery power, the presence of this component provides a number of important additional functions, such as the ability to stepwise adjust the brightness of the light, flashing mode, temperature control, battery discharge, and operating modes.

When choosing the optimal types of LEDs for flashlights, you should remember that the larger the area of the LED, the easier it is to create a wide beam with its help and vice versa. The more lumens the flashlight produces, the brighter the light stream and the shorter the battery life.

LED flashlight.

http://ua1zh. *****/led_driver/led_driver. htm

Autumn has come, it’s already dark outside, and there are still no light bulbs in the entrance. Screwed it in... The next day - no again. Yes, these are the realities of our lives... I bought a flashlight for my wife, but it turned out to be too big for her purse. I had to do it myself. The scheme does not pretend to be original, but maybe it will work for someone - judging by the Internet forums, interest in such technology is not decreasing. I foresee possible questions - “Isn’t it easier to take a ready-made chip like the ADP1110 and not bother?” Yes, of course, it's much easier
But the cost of this chip in Chip&Dip is 120 rubles, the minimum order is 10 pcs and the execution time is a month. The production of this design took me exactly 1 hour 12 minutes, including time for prototyping, with a cost of 8 rubles per LED. A self-respecting radio amateur will always find the rest in his trash bin.

Actually the whole scheme:

HHonestly, I will swear if someone asks - on what principle does all this work?

And I will scold you even moreYes, if they ask for a signet...

Below is an example of a practical design. For the case, a suitable box from some kind of perfume was taken. If desired, you can make the flashlight even more compact - everything is determined by the housing used. Now I’m thinking about putting a flashlight into the body from a thick marker.

A little about the details: I took the transistor KT645. This one just came to hand. You can experiment with selecting VT1 if you have time and thereby slightly increase the efficiency, but it is unlikely that you can achieve a radical difference with the transistor used. The transformer is wound on a suitable ferrite ring with high permeability with a diameter of 10 mm and contains 2x20 turns of PEL-0.31 wire. The windings are wound with two wires at once, it is possible without twisting - this is not a ShTTL... Rectifier diode - any Schottky, capacitors - tantalum SMD for a voltage of 6 volts. LED - any super-bright white with a voltage of 3-4 volts. When using a battery with a nominal voltage of 1.2 volts as a battery, the current through the LED I had was 18 mA, and when using a dry battery with a nominal voltage of 1.5 volts, it was 22 mA, which provides maximum light output. Overall the device consumed approximately 30-35mA. Considering the occasional use of the flashlight, the battery may well last for a year.

When battery voltage is applied to the circuit, the voltage drop across resistor R1 in series with the high-brightness LED is 0 V. Therefore, transistor Q2 is off and transistor Q1 is in saturation. The saturated state of Q1 turns on the MOSFET, thereby supplying battery voltage to the LED through the inductance. As the current flowing through resistor R1 increases, this turns on transistor Q2 and turns off transistor Q1 and therefore the MOSFET transistor. During the MOSFET's off state, the inductance continues to provide power to the LED through the Schottky diode D2. The HB LED is a 1 W Lumiled white LED. Resistor R1 helps control the brightness of the LED. Increasing the value of resistor R1 reduces the brightness of the glow. http://www. *****/shem/schematics. html? di=55155

Making a modern flashlight

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Rice. 1. Schematic diagram current stabilizer

Using the pulse current stabilizer circuit (Fig. 1), long known in amateur radio circles, using modern affordable radio components, you can assemble a very good LED flashlight.

For modification and alteration, the author purchased a mongrel flashlight with a 6 V 4 Ah battery, a “spotlight” on a 4.8 V 0.75 A lamp and a diffused light source on a 4 W LDS. The “original” incandescent light bulb almost immediately turned black due to operation at too high a voltage and failed after several hours of operation. A full battery charge was enough for 4-4.5 hours of operation. Turning on the LDS generally loaded the battery with a current of about 2.5 A, which led to its discharge after 1-1.5 hours.

To improve the flashlight, white LEDs of an unknown brand were purchased on the radio market: one with a beam divergence of 30o and an operating current of 100 mA for the “spotlight”, as well as a dozen matte LEDs with an operating current of 20 mA to replace the LDS. According to the scheme (Fig. 1), a stable current generator was assembled with an efficiency of about 90%. The circuitry of the stabilizer made it possible to use a standard switch to switch the LEDs. The LED2 indicated in the diagram is a battery of 10 parallel connected identical white LEDs, each rated for a current of 20 mA. Parallel connection of LEDs does not seem entirely advisable due to the nonlinearity and steepness of their current-voltage characteristics, but experience has shown that the spread of LED parameters is so small that even with such a connection their operating currents are almost the same. What is important is the complete identity of the LEDs; if possible, they should be purchased “from the same factory packaging.”

After modification, the “spotlight” of course became a little weaker, but it was quite sufficient, the diffused light mode did not visually change. But now, thanks to the high efficiency of the current stabilizer, when using the directional mode, a current of 70 mA is consumed from the battery, and in the scattered light mode, mA, that is, the flashlight can work without recharging for about 50 or 25 hours, respectively. Brightness does not depend on the degree of discharge of the battery due to current stabilization.

The current stabilizer circuit works as follows: When power is applied to the circuit, transistors T1 and T2 are locked, T3 is open, because an unlocking voltage is applied to its gate through resistor R3. Due to the presence of inductor L1 in the LED circuit, the current increases smoothly. As the current in the LED circuit increases, the voltage drop across the R5-R4 chain increases; as soon as it reaches approximately 0.4 V, transistor T2 will open, followed by T1, which in turn will close the current switch T3. The increase in current stops, a self-induction current appears in the inductor, which begins to flow through diode D1 through the LED and a chain of resistors R5-R4. As soon as the current decreases below a certain threshold, transistors T1 and T2 will close, T3 will open, which will lead to a new cycle of energy accumulation in the inductor. In normal mode, the oscillatory process occurs at a frequency of the order of tens of kilohertz.

About the details: there are no special requirements for the parts; you can use any small-sized resistors and capacitors. Instead of the IRF510 transistor, you can use the IRF530, or any n-channel field-effect switching transistor with a current of more than 3 A and a voltage of more than 30 V. Diode D1 must be with a Schottky barrier for a current of more than 1 A; if you install even a regular high-frequency type KD212, the efficiency will decrease up to 75-80%. The inductor can be homemade; it is wound with a wire no thinner than 0.6 mm, or better - a bundle of several thinner wires. About 20-30 turns of wire per armor core B16-B18 are required with a non-magnetic gap of 0.1-0.2 mm or close from 2000NM ferrite. If possible, the thickness of the non-magnetic gap is selected experimentally according to the maximum efficiency of the device. Good results can be obtained with ferrites from imported inductors installed in pulse blocks nutrition as well as energy saving lamps. Such cores have the appearance of a spool of thread and do not require a frame or a non-magnetic gap. Coils on toroidal cores made of pressed iron powder, which can be found in computer power supplies (the output filter inductors are wound on them), work very well. The non-magnetic gap in such cores is evenly distributed throughout the volume due to the production technology.

The same stabilizer circuit can be used in conjunction with other batteries and galvanic cell batteries with a voltage of 9 or 12 volts without any change in the circuit or cell ratings. The higher the supply voltage, the less current the flashlight will consume from the source, its efficiency will remain unchanged. The operating stabilization current is set by resistors R4 and R5. If necessary, the current can be increased to 1 A without the use of heat sinks on the parts, only by selecting the resistance of the setting resistors.

The battery charger can be left “original” or assembled according to any of the known schemes, or even used externally to reduce the weight of the flashlight.

The device is being assembled wall-mounted in the free cavities of the flashlight body and filled with hot glue for sealing.

It’s also a good idea to add a new device to the flashlight: a battery charge indicator (Fig. 2).

Rice. 2. Schematic diagram of the battery charge level indicator.

The device is essentially a voltmeter with a discrete LED scale. This voltmeter has two operating modes: in the first, it estimates the voltage on the battery being discharged, and in the second, the voltage on the battery being charged. Therefore, in order to correctly assess the degree of charge, different voltage ranges were selected for these operating modes. In the discharge mode, the battery can be considered fully charged when the voltage on it is 6.3 V, when it is completely discharged, the voltage will drop to 5.9 V. In the process of charging the voltages are different, a battery is considered fully charged if the voltage at the terminals is 7, 4 V. In connection with this, an algorithm for the operation of the indicator has been developed: if the charger is not connected, that is, at the “+ Charge” terminal there is no voltage, the “orange” crystals of the two-color LEDs are de-energized and transistor T1 is locked. DA1 generates the reference voltage determined by resistor R8. The reference voltage is supplied to a line of comparators OP1.1 - OP1.4, on which the voltmeter itself is implemented. To see how much charge is left in the battery, you need to press the S1 button. In this case, supply voltage will be supplied to the entire circuit and, depending on the voltage on the battery, a certain number of green LEDs will light up. When fully charged, the entire column of 5 green LEDs will light up; when completely discharged, only one, the lowest LED, will light up. If necessary, the voltage is adjusted by selecting the resistance of resistor R8. If it turns on Charger, through the terminal “+ Charge.” and diode D1 supplies voltage to the circuit, including the “orange” parts of the LEDs. In addition, T1 opens and connects resistor R9 in parallel with resistor R8, as a result of which the reference voltage generated by DA1 increases, which leads to a change in the operating thresholds of the comparators - the voltmeter is adjusted to a higher voltage. In this mode, all the time the battery is charging, the indicator displays the charging process also with a column of glowing LEDs, only this time the column is orange.

Homemade LED flashlight

The article is dedicated to radio amateur tourists, and to everyone who has in one way or another encountered the problem of an economical lighting source (for example, a tent at night). Although LED flashlights have not surprised anyone lately, I will still share my experience in creating such a device, and will also try to answer questions from those who want to repeat the design.

Note: The article is intended for “advanced” radio amateurs who are well aware of Ohm’s law and have held a soldering iron in their hands.

The basis was a purchased flashlight "VARTA" powered by two AA batteries:

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Here's what the assembled diagram looks like:

The reference points are the legs of the DIP chip.

A few explanations to the diagram: Electrolytic capacitors - tantalum CHIP. They have low series resistance, which slightly improves efficiency. Schottky diode - SM5818. The chokes had to be connected in parallel, because there was no suitable rating. Capacitor C2 - K10-17b. LEDs - super bright white L-53PWC "Kingbright". As can be seen in the figure, the entire circuit easily fits into the empty space of the light-emitting unit.
The output voltage of the stabilizer in this connection circuit is 3.3V. Since the voltage drop across the diodes in the nominal current range (15-30mA) is about 3.1V, the extra 200mV had to be sown on a resistor connected in series with the output. In addition, a small series resistor improves load linearity and circuit stability. This is due to the fact that the diode has a negative TCR, and when warmed up, its forward voltage drop decreases, which leads to a sharp increase in the current through the diode when it is powered from a voltage source. There was no need to equalize the currents through parallel-connected diodes - no differences in brightness were observed by eye. Moreover, the diodes were of the same type and taken from the same box.
Now about the design of the light emitter. Perhaps this is the most interesting detail. As can be seen in the photographs, the LEDs in the circuit are not tightly sealed, but are a removable part of the structure. I decided to do this in order not to screw up the flashlight, and if necessary, I could insert an ordinary light bulb into it. As a result of much thought about killing two birds with one stone, this design was born:

I think that no special explanation is required here. The original light bulb from the same flashlight is gutted, 4 cuts are made in the flange on 4 sides (one was already there). 4 LEDs are arranged symmetrically in a circle with some splay for a larger coverage angle (I had to file them a little at the base). The positive terminals (as it turned out according to the diagram) are soldered onto the base near the cuts, and the negative terminals are inserted from the inside into the central hole of the base, cut off and also soldered. The result is such a “lampodiode”, which takes the place of an ordinary incandescent light bulb.

And finally, about the test results. Half-dead batteries were taken for testing in order to quickly bring them to the finish line and understand what the newly made flashlight is capable of. The battery voltage, load voltage, and load current were measured. The run started with a battery voltage of 2.5V, at which the LEDs no longer light up directly. Stabilization of the output voltage (3.3V) continued until the supply voltage was reduced to ~1.2V. The load current was about 100mA (~ 25mA per diode). Then the output voltage began to decrease smoothly. The circuit has switched to a different operating mode, in which it no longer stabilizes, but outputs everything it can. In this mode, it worked up to a supply voltage of 0.5V! The output voltage dropped to 2.7V, and the current from 100mA to 8mA. The diodes were still on, but their brightness was only enough to illuminate the keyhole in the dark entrance. After this, the batteries practically stopped discharging, because the circuit stopped consuming current. After running the circuit in this mode for another 10 minutes, I became bored and turned it off, because further running was of no interest.

The brightness of the glow was compared with a conventional incandescent light bulb at the same power consumption. A 1V 0.068A light bulb was inserted into the flashlight, which at a voltage of 3.1V consumed approximately the same current as the LEDs (about 100mA). The result is clearly in favor of LEDs.

Part II. A little about efficiency or “There is no limit to perfection.”

More than a month has passed since I assembled my first circuit to power an LED flashlight and wrote about it in the above article. To my surprise, the topic turned out to be very popular, judging by the number of reviews and site visits. Since then I have gained some understanding of the subject :), and I considered it my duty to take the topic more seriously and conduct more thorough research. This idea was also brought to me by communication with people who solved similar problems. I would like to tell you about some new results.

Firstly, I should have immediately measured the efficiency of the circuit, which turned out to be suspiciously low (about 63% with fresh batteries). Secondly, I understood the main reason for such low efficiency. The fact is that those miniature chokes that I used in the circuit have an extremely high ohmic resistance - about 1.5 ohms. There could be no talk of saving electricity with such losses. Thirdly, I discovered that the amount of inductance and output capacitance also affects the efficiency, although not as noticeably.

I somehow didn’t want to use a DM-type rod choke because of its large size, so I decided to make the choke myself. The idea is simple - you need a low-turn choke, wound with a relatively thick wire, and at the same time quite compact. The ideal solution It turned out to be a ring made of µ-permalloy with a permeability of about 50. There are ready-made chokes on sale on such rings, widely used in all kinds of switching power supplies. I had at my disposal such a 10 μG choke, which has 15 turns on the K10x4x5 ring. There was no problem rewinding it. The inductance had to be selected based on the efficiency measurement. In the range of 40-90 µG the changes were very insignificant, less than 40 - more noticeable, and at 10 µG it became very bad. I did not raise it above 90 μH, because the ohmic resistance increased, and the thicker wire “inflated” the dimensions. In the end, more for aesthetic reasons, I settled on 40 turns of PEV-0.25 wire, since they lay evenly in one layer and the result was about 80 μG. The active resistance turned out to be about 0.2 ohms, and the saturation current, according to calculations, was more than 3A, which is enough for the eyes... I replaced the output (and at the same time the input) electrolyte with 100 μF, although without compromising the efficiency it can be reduced to 47 μF. As a result, the design has undergone some changes, which, however, did not prevent it from maintaining its compactness:

Laboratory work" href="/text/category/laboratornie_raboti/" rel="bookmark">laboratory work and took down the main characteristics of the scheme:

	1. Dependence of the output voltage measured on capacitor C3 on the input. I have taken this characteristic before and I can say that replacing the throttle with a better one gave a more horizontal plateau and a sharp break.
	2. It was also interesting to track the change in current consumption as the batteries discharged. The “negativity” of the input resistance, typical of key stabilizers, is clearly visible. The peak consumption occurred at a point close to the reference voltage of the microcircuit. A further drop in voltage led to a decrease in the support, and hence the output voltage. The sharp drop in current consumption on the left side of the graph is caused by the nonlinearity of the I-V characteristics of the diodes.
	3. And finally, the promised efficiency. Here it was measured by the final effect, i.e. by the power dissipation on the LEDs. (5 percent is lost on the ballast resistance). The chip manufacturers did not lie - with the correct design it gives the required 87%. True, this is only with fresh batteries. As the current consumption increases, the efficiency naturally decreases. At an extreme point, it generally drops to the level of a steam locomotive. Increase in efficiency with further reduction in voltage practical value can’t imagine, because the flashlight is already “on its last legs” and shines very weakly.

Looking at all these characteristics, we can say that the flashlight shines confidently when the supply voltage drops to 1V without a noticeable decrease in brightness, i.e. the circuit actually handles a three-fold voltage drop. An ordinary incandescent light bulb with such a discharge of batteries is unlikely to be suitable for lighting.

If something remains unclear to someone, write. I will respond by letter and/or add to this article.

Vladimir Rashchenko, E-mail: rashenko (at) inp. nsk. su

May, 2003.

Velofara - what's next?

So, first headlight built, tested and tested. What are the future promising directions for LED headlight manufacturing? The first stage will probably be a further increase in capacity. I am planning to build a 10-diode headlight with a switchable 5/10 operating mode. Well, further improvement of quality requires the use of complex microelectronic components. For example, it seems to me that it would be nice to get rid of quenching/equalizing resistors - after all, 30-40% of the energy is lost on them. And I would like to have current stabilization through LEDs, regardless of the discharge level of the source. The best option would be to sequentially switch on the entire chain of LEDs with current stabilization. And in order not to increase the number of series batteries, this circuit also needs to increase the voltage from 3 or 4.5 V to 20-25 V. These are, so to speak, specifications for the development of an “ideal headlight”.
It turned out that specialized ICs are produced specifically to solve such problems. Their area of application is controlling the backlight LEDs of LCD monitors for mobile devices- laptops. cell phones, etc. Dima brought me to this information gdt (at) *****- THANK YOU!

In particular, a line of ICs for various purposes for controlling LEDs is produced by Maxim (Maxim Integrated Products, Inc), on whose website ( http://www.) the article "Solutions for Driving White LEDs" (Apr 23, 2002) was found. Some of these "solutions" are great for bicycle lights:

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Option 1. MAX1848 chip, controlling a chain of 3 LEDs.

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Option 3: Another scheme for switching on feedback is possible - from a voltage divider.

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Option 5. Maximum power, several chains of LEDs, MAX1698 chip

current mirror", chip MAX1916.

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Option 8. Chip MAX1759.

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Option 10. MAX619 chip - perhaps. the most simple circuit inclusions. Operation when the input voltage drops to 2 V. Load 50 mA at Uin>3 V.

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Option 12. The ADP1110 chip is rumored to be more common than MAXs, it works starting from Uin = 1.15 V ( !!! only one battery!!!) Uout. up to 12 V

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Option 14. Microcircuit LTC1044 - a very simple connection diagram, Uin = from 1.5 to 9 V; Uout = up to 9 V; load up to 200mA (but, however, typical 60 mA)

As you can see, all this looks very tempting :-) All that remains is to find these microcircuits inexpensively somewhere....

Hooray! Found ADP1rub. with VAT) We are building a new powerful headlight!

10 LEDs, switchable 6\10, five chains of two.

MAX1848 White LED Step-Up Converter to SOT23

MAX1916 Low-Dropout, Constant-Current Triple White LED Bias Supply

Display Drivers and Display Power Application Notes and Tutorials

Charge Pump Versus Inductor Boost Converter for White LED Backlights

Buck/Boost Charge-Pump Regulator Powers White LEDs from a Wide 1.6V to 5.5V Input

Analog ICs for 3V Systems

On the Rainbow Tech website: Maxim: DC-DC conversion devices(pivot table)

On the Premier Electric website: Pulse regulators and controllers for power supply without galvanics. interchanges(pivot table)

On the Averon website - microcircuits for power supplies(Analog Devices) - summary table

Powering LEDs with ZXSC300

Davidenko Yuri. Lugansk
Email address -
david_ukr (at) ***** (replace (at) with @)

The feasibility of using LEDs in flashlights, bicycle lights, and local and emergency lighting devices today is beyond doubt. The light output and power of LEDs is growing, and their prices are falling. There are more and more light sources that use white LEDs instead of the usual incandescent lamp and it is not difficult to buy them. Shops and markets are filled with LED products made in China. But the quality of these products leaves much to be desired. Therefore, there is a need to modernize affordable (primarily priced) LED light sources. Yes, and replacing incandescent lamps with LEDs in high-quality Soviet-made flashlights also makes sense. I hope that the following information will not be superfluous.

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As is known, an LED has a nonlinear current-voltage characteristic with a characteristic “heel” in the initial section.

Rice. 1 Volt-ampere characteristics of a white LED.

As we can see, the LED begins to glow if a voltage of more than 2.7 V is applied to it. When powered by a galvanic or rechargeable battery, the voltage of which gradually decreases during operation, the brightness of the radiation will vary widely. To avoid this, it is necessary to power the LED with a stabilized current. And the current must be rated for this type of LED. Typically for standard 5 mm LEDs it averages 20 mA.

For this reason, it is necessary to use electronic current stabilizers, which limit and stabilize the current flowing through the LED. It is often necessary to power an LED from one or two batteries with a voltage of 1.2 - 2.5 V. For this, step-up voltage converters are used. Since any LED is essentially a current device, from an energy efficiency standpoint it is advantageous to provide direct control of the current flowing through it. This eliminates losses that occur on the ballast (current-limiting) resistor.

One of the optimal options for powering various LEDs from autonomous current sources of low voltage 1-5 volts is to use a specialized ZXSC300 microcircuit from ZETEX. ZXSC300 is a pulsed (inductive) DC-DC boost converter with pulse frequency modulation.

Let's look at the operating principle of the ZXSC300.

On the image Fig.2 one of the standard schemes nutrition white LED pulse current using ZXSC300. The pulsed power supply mode of the LED allows you to make the most efficient use of the energy available in the battery or accumulator.

In addition to the ZXSC300 microcircuit itself, the converter contains: a 1.5 V battery, a storage choke L1, a power switch - transistor VT1, a current sensor - R1.

The converter works in its traditional way. For some time, due to the pulse coming from generator G (via the driver), transistor VT1 is open and the current through inductor L1 increases linearly. The process lasts until the voltage drop across the current sensor - low-resistance resistor R1 reaches 19 mV. This voltage is enough to switch the comparator (the second input of which is supplied with a small reference voltage from the divider). The output voltage from the comparator is supplied to the generator, as a result of which the power switch VT1 closes and the energy accumulated in the inductor L1 enters the LED VD1. Then the process is repeated. Thus, fixed portions of energy are supplied to the LED from the primary power source, which it converts into light.

Energy management occurs using pulse-frequency modulation PFM (PFM Pulse Frequency Modulation). The principle of PFM is that the frequency changes, but the duration of the pulse or pause, respectively, the open (On-Time) and closed (Off-Time) state of the key remains constant. In our case, the Off-Time remains unchanged, i.e. the pulse duration at which the external transistor VT1 is in the closed state. For the ZXSC300 controller, Toff is 1.7 µs.

This time is enough to transfer the accumulated energy from the inductor to the LED. The duration of the pulse Ton, during which VT1 is open, is determined by the value of the current-measuring resistor R1, the input voltage, and the difference between the input and output voltage, and the energy that accumulates in the inductor L1 will depend on its value. It is considered optimal when the total period T is 5 µs (Toff + Ton). The corresponding operating frequency is F=1/5μs =200 kHz.

With the element ratings indicated in the diagram in Fig. 2, the oscillogram of the voltage pulses on the LED looks like

Fig.3 type of voltage pulses on the LED. (grid 1V/div, 1μs/div)

A little more detail about the parts used.

Transistor VT1 - FMMT617, npn transistor with a guaranteed collector-emitter saturation voltage of no more than 100 mV at a collector current of 1 A. Capable of withstanding impulse current collector up to 12 A (constant 3 A), collector-emitter voltage 18 V, current transfer coefficient 150...240. Dynamic characteristics transistor: on/off time 120/160 ns, f =120 MHz, output capacitance 30 pF.

FMMT617 is the best switching device that can be used with ZXSC300. It allows you to obtain high conversion efficiency with an input voltage of less than one volt.

Storage choke L1.

Both industrial SMD Power Inductor and homemade ones can be used as a storage choke. Choke L1 must withstand the maximum current of power switch VT1 without saturating the magnetic circuit. The active resistance of the inductor winding should not exceed 0.1 Ohm, otherwise the efficiency of the converter will noticeably decrease. Ring magnetic cores (K10x4x5) from power filter chokes used in old computer motherboards are well suited as a core for self-winding. Today, used computer hardware can be purchased at bargain prices on any radio market. And hardware is an inexhaustible source of various parts for radio amateurs. When winding yourself, you will need an inductance meter for control.

Current measuring resistor R1. Low-resistance resistor R1 47 mOhm is obtained by parallel connection of two SMD resistors of standard size 1206, 0.1 Ohm each.

LED VD1.

White LED VD1 with a rated operating current of 150 mA. The author's design uses two four-crystal LEDs connected in parallel. The rated current of one of them is 100 mA, the other 60 mA. The operating current of the LED is determined by passing a stabilized direct current through it and monitoring the temperature of the cathode (negative) terminal, which is a radiator and removes heat from the crystal.

At the rated operating current, the temperature of the heat sink should not exceed degrees. Instead of one VD1 LED, you can also use eight standard 5 mm LEDs connected in parallel with a current of 20 mA.

Appearance of the device

Rice. 4a.

Rice. 4b.

Shown in Fig. 5

Rice. 5(size 14 by 17 mm).

When developing boards for such devices, it is necessary to strive for the minimum values of capacitance and inductance of the conductor connecting K VT1 with the storage choke and LED, as well as for the minimum inductance and active resistance of the input and output circuits and the common wire. The resistance of the contacts and wires through which the supply voltage is supplied should also be minimal.

In the following diagrams Fig. 6 and Fig. Figure 7 shows a method for powering high-power Luxeon type LEDs with a rated operating current of 350 mA

Rice. 6 Power supply method for high-power Luxeon LEDs

Rice. 7 The method of powering high-power LEDs of the Luxeon type - ZXSC300 is powered from the output voltage.

Unlike the previously discussed circuit, here the LED is powered not pulsed, but direct current. This makes it easy to control the operating current of the LED and the efficiency of the entire device. Feature of the converter in Fig. 7 is that ZXSC300 is powered by output voltage. This allows the ZXSC300 to operate (after startup) when the input voltage drops down to 0.5 V. The VD1 diode is a Schottky diode designed for a current of 2A. Capacitors C1 and C3 are ceramic SMD, C2 and C3 are tantalum SMD. Number of LEDs connected in series.

Resistance of the current measuring resistor, mOhm.

Inductance of storage choke, μH.

Today, powerful 3 - 5 W LEDs from various manufacturers (both famous and not so famous) have become available for use.

And in this case, the use of ZXSC300 makes it possible to easily solve the problem of efficiently powering LEDs with an operating current of 1 A or more.

It is convenient to use an n-channel (operating from 3 V) Power MOSFET as a power switch in this circuit; you can also use an assembly of the FETKY MOSFET series (with a Schottky diode in one SO-8 package).

With the ZXSC300 and a few LEDs, you can easily breathe new life into your old flashlight. The FAR-3 battery flashlight was modernized.

Fig.11

LEDs were used 4-crystal with a rated current of 100 mA - 6 pcs. Connected in series by 3. To control the light flux, two converters on the ZXSC300 are used, with independent on/off. Each converter operates on its own triple LED.

Fig.12

The converter boards are made on double-sided fiberglass, the second side is connected to the power supply minus.

Fig.13

Fig.14

The FAR-3 flashlight uses three sealed batteries NKGK-11D (KCSL 11) as batteries. The nominal voltage of this battery is 3.6 V. The final voltage of a discharged battery is 3 V (1 V per cell). Further discharge is undesirable because it will shorten the battery life. And further discharge is possible - the converters on the ZXSC300 operate, as we remember, down to 0.9 V.

Therefore, to control the voltage on the battery, a device was designed, the circuit of which is shown in Fig. 15.

Fig.15

IN this device Inexpensive available element base is used. DA1 - LM393 is a well-known dual comparator. A reference voltage of 2.5 V is obtained using TL431 (analogue of KR142EN19). The response voltage of the comparator DA1.1, about 3 V, is set by the divider R2 - R3 (selection of these elements may be required for accurate operation). When the voltage on battery GB1 drops to 3 V, the red LED HL1 lights up, if the voltage is more than 3 V, then HL1 goes out and the green LED HL2 lights up. Resistor R4 determines the hysteresis of the comparator.

The control circuit board is shown in Rice. 16 ( size 34 by 20 mm).

If you have any difficulties purchasing the ZXSC300 microcircuit, FMMT617 transistor or low-resistance SMD resistors 0.1 Ohm, you can contact the author by e-mail david_ukr (at) *****

You can purchase the following components (delivery by mail)

Elements	Quantity	Price, $	Price, UAH
Chip ZXSC 300 + transistor FMMT 617
Resistor 0.1 Ohm SMD size 0805
Printed circuit board Fig. 8

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Making your own LED flashlight

Understanding what parameters the operation of a flashlight depends on is equally important for those who want to choose a ready-made model and those who want to design a device with their own hands (be it a keychain flashlight with an LED, a pocket, head-mounted or hiking version). Repairing flashlights mainly depends on their design, and replacing some elements requires special skills. Bright is not the only definition for a quality device.

The first step is to identify the purpose of the flashlight. It is hardly possible to identify a universal device that is equally effective in all conditions. In the end, a small pocket flashlight can never compare with powerful stationary equipment, and homemade devices are not always superior to ready-made ones (even those made in China), and it’s not just how the LED was selected.

Dimensions

It is necessary to determine the size of the flashlight in 2 cases: to be able to carry it with you (in your pocket, bag, etc.), and to correctly calculate the body when drawing up the diagram yourself.

Dimensions also need to be known when selecting accessories. A headlamp is worn on a special tape, and a hiking lamp is worn on a clip or in a fabric case (on the belt).

Luminous flux parameters

Often, the brightest flashlight is required, but a large number of lumens does not always completely determine this indicator. No less important role assigned to the lighting dispersion angle. A simple keychain flashlight with an LED or any pocket version can handle illumination of a small area. The narrower the beam, the further a device can shine, for example, a headlamp for hiking.

Important: The lens can radically change the characteristics of the device. The operation of focusable flashlights is quite simple: the position of the lens adjusts the width and tilt of the beam as it approaches/moves away from the LED.
Selection of the LED itself

It is the light source that determines most of the flashlight's performance (how bright it is). The operation of the device is affected not only by the LED itself, but also by the value of its operating current. The current strength must be taken into account so as not to inadvertently burn the device, because repairing the flashlight is not always appropriate. LEDs and their strings can be grouped in different ways to increase range or coverage area (the largest is usually located closer to the center).

Work offline

Duration of work is a very relative value. It is determined not only by the choice of battery, but also by the flashlight mode, for which the LED is responsible. For both homemade devices and ready-made ones, you can install a timer to save energy. Autonomous mode can last for hours (pocket and headlamps) and even days (emergency and search), this period is influenced mainly by the main characteristics.

Types of batteries

Batteries vary depending on the principle of energy generation; among the most popular types are the following:

lithium (Li-Ion);
nickel metal hydride (NiMH);
nickel-cadmium (NiCd);
lead-acid;
lithium polymer (Li‑pol);
nickel-zinc (NiZn).

A small flashlight (pocket or headlamp) can also operate on ordinary AA batteries; in other cases, it is better to select the type of battery based on general requirements so that repairing or replacing the battery does not become an unsolvable task.

Operating modes

The simpler the device, the fewer modes it has in its arsenal. The simplest bright keychain flashlight with an LED, pocket and headlamps, as a rule, have no more than one. How more complex system– the greater the probability of failure of one of the components, i.e. the more often they require repairs.

Classification of modes:

brightness (minimum-medium-maximum);
signal (strobe);
programmable (manually configured by the user).

Exposure to external factors

The circuit itself and the LED must be protected from shock, shaking, dust and dirt. For more serious devices, it is better to ensure moisture resistance. This can be quite difficult not only when assembling it yourself, but also after purchasing ready-made models. It is better to check the water resistance in advance, especially on Chinese-made flashlights, in order to be able to carry out repairs in a timely manner.

Mounting location

The flashlight should be easy to use. To do this, you need to think in advance about how the circuit will be drawn up - the location of the buttons responsible for how the LED, auxiliary lenses and diffusers work. It is important to be able to adjust the mount (headlamp or bicycle light), clamping density, etc.

Current stabilization

The operating mode of the LED flashlight directly depends on the supplied current; other characteristics may be similar. Stabilized devices are considered brighter and more stable, but when discharged they quickly go out. An unstabilized flashlight is less bright, but the lamps go out gradually, eventually reducing their brightness to 0.

Having understood the parameters of the device, it becomes much easier not only to select the type of flashlight you are interested in (pocket, head, mounted, keychain flashlight with LED), but also to determine the required elements, if you have your own circuit and selected the appropriate LED, as well as to carry out partial repairs of the device .