How to power a 10 W LED. LED lighting workshop in Dnepr. Connection errors
In the title of the article I specifically did not write that the flashlight is LED, since now it has become impossible to find non-LED flashlights on sale. Maybe some people still have it lying around in their sheds and bedside tables. As you can see, the dispute between incandescent lamps and LEDs was finally resolved in favor of the latter. Now ordinary glass light bulbs for low voltage have become, in the words of A. Raikin: “diffisit”. Try to buy them in a store - you will be surprised :) So, to create our new flashlight with a power of 10 watts, we will use an affordable and inexpensive Cree LED with a similar power.
We also need a 3V 1.5A LED driver, a capacious 3.7V lithium-ion battery from the phone, a mobile phone charger (almost any), a power button, a power socket (for the charger) and a case. Let's look at the last point in a little more detail.
For the base of a ten-watt flashlight, you need to choose something large and preferably metal. Don’t forget - an LED of such power heats up quite a lot and the heat sink must match. And the battery will have to deliver a current of more than an ampere, so it makes sense to use lithium batteries from laptops.
In my version, I used the third lampshade of a nickel-plated chandelier, which I recently used on a tube ULF. We make a hole in it for the power socket to charge the battery, and the rest is in the lampshade as is.
There is no flashlight circuit as such, all components are taken ready-made. You just have to solder all these modules together according to the given figure.
A 10-watt LED was screwed to a round piece of aluminum 1cm thick. It will be both a radiator and a reflector (polished it until it shines). Don't forget to use thermal paste - it significantly improves the cooling of the LED element. Its price is only 0.5 per tube and the paste lasts for a long time.
Having placed all the elements of the flashlight inside the body, we solder them with flexible wires in good insulation (do not forget about the voltage 220V!). Lastly, screw on the aluminum reflector disk with the LED.
Although there are hundreds of different models and wattages of diode flashlights on sale, buying a flashlight of 10 watts or more is very problematic. And in online stores they cost under a hundred dollars. Here, this device is assembled from scrap materials literally in the evening, with expenses only for the LED itself. Therefore, its self-assembly is 100% justified.
10 W LED is a powerful semiconductor device. The scope of its application is often not limited to lamps and spotlights. The chip is also very popular among those who like to make their own lighting devices.
Application area
10 W are widely used in various lighting devices. All areas can be divided into general and special purposes. General purpose includes the use of LEDs in lamps, luminaires, spotlights, and special purpose includes use for lighting in greenhouses and. The second option is the so-called, and not only. The trick is that the emission spectrum of this LED is optimal for plant growth, both on land and in water. And in addition to algae and fish, lighting with 10-watt LEDs has a beneficial effect on the development of corals, so aquarium lovers are frequent consumers of this radio component. All these wonderful properties are manifested in a certain combination of crystal colors. As for the use of the described semiconductor device for general-purpose lighting devices, in addition to household lamps, LEDs are excellently used for making car headlights, traffic lights, and road lighting.
LED design, design options
The COB 10 W LED is a compact module made using chip-on-board technology. The fundamental difference from SMD is that several crystals are placed together on a board and covered with a common layer of phosphor. This significantly reduces the cost of the matrix. It consists of 9 crystals: three parallel chains of three serially connected crystals in each. Externally, LED 10 W may differ in the shape of the conductive substrate. For example, the company's LED looks as shown in the figure. Its substrate is star-shaped and made of aluminum.
The module body is made of heat-resistant plastic, and the lens is made of epoxy resin. Classic LED 10 W looks as shown in the diagram, but in practice the overall dimensions vary depending on the manufacturer.
Do not forget that the LED is a polar element, so pay attention to the markings when installing. A prerequisite for adequate functioning of a 10 W LED is the presence of a heat sink. It can be organized using an aluminum or copper radiator. Lubricate the LED substrate with thermal conductive paste or hot melt adhesive for better heat transfer. Sometimes a cooler is additionally installed, which provides air circulation to cool the radiator fins.
In the video you can see a test of a 10W LED and recommendations for connecting such an element. Here's what the 10W LED wiring diagram should look like.
The power source can be a car battery, a computer power supply, or a specially purchased 12-volt source. In order to avoid overheating (despite the heatsink) and protect the LED, it is imperative to connect it not directly to the source, but through any voltage stabilizer. The diagram shows an LM-317 integrated voltage stabilizer, but another one with suitable parameters can be used. With the help of a regular cable and a resistor, you will provide yourself with a guaranteed 12 V output and the current will not exceed 1 A, which is the key to the longevity of your device.
Characteristics
The parameters of the 10-watt LED allow it to be in great demand in the line of super-bright LEDs. The supply voltage ranges from 9 to 12 Volts. The glow angle is 120° – the graph is shown below.
The rated forward current is 1 A, the pulsating forward current is up to 2 A. The luminous flux is in the range of 600-1080 lm. For comparison, a 75 W incandescent lamp produces a glow of 935 lm. Thus, you can roughly estimate how bright the glow of a given semiconductor device will be. The reverse voltage is 50 V., depending on the manufacturer, 30-100 thousand hours. Operating temperature ranges from -30°C to 80°C. The color temperature of a 10W LED covers the spectrum from 2300K (warm white) to 10000K (cool white).
Manufacturers
The leaders in the production of high-power LEDs, such as LED 10 W, are dispersed in three parts of the world. Among them are the American company Cree (which we have already mentioned and demonstrated a sample of its products), the Japanese Nichia (a pioneer in the field of LED technology), and also the German Osram (more known to domestic buyers).
Branded LED products are more expensive than their noname counterparts, but in the second case no one guarantees quality.
Let's consider what features you will encounter if you decide to purchase Chinese cheap 10-watt LEDs. Firstly, if you compare carefully, the 9 matrix crystals themselves are smaller in size than those of high-quality modules. This will naturally affect the light output during their operation. Secondly, the strong unevenness of the glow of each crystal. This is noticeable, however, only at a reduced current, but, nevertheless, this feature affects the degradation rate of the entire LED module.
10 watt fakes from China
In the picture you can observe the uneven glow of individual crystals of the module, and how it levels out with increasing current. Thirdly, in low-quality LEDs, the conductors connecting the crystals are very thin and can break due to careless movement, which will interrupt the functioning of at least one triple of successive crystals.
Summarizing what was described above, I would like to highlight the important points of the article for memorization. 10 W LEDs as light-emitting sources are widely used in practice for the manufacture of car lamps, flashlights, spotlights and other lighting devices. Heatsink cooling is critical for proper LED performance. Power is supplied from a 12V source through a driver (voltage stabilizer). A well-known brand guarantees uninterrupted operation for the entire stated period, but problems may arise with Chinese inexpensive analogues.
Well-known cheap LEDs (see below) are declared as 10 watt. The quality is the same weak everywhere, the real power is 4 W, if you give a current of more than 0.4 A, they degrade in 2-3 months. Warm ones give a frankly yellow-green light, cold ones give a blue light.
The Hagood Technology store was found by chance. The seller's website offers only 10-watt LEDs for a voltage of 9-10 V. They are called Cheapest - the cheapest.
On the left in the photo are the “cold” ones of the new standard size, on the right are the “warm” ones, bought there a year ago.
The illumination at milliamps is uniform.
Next we agree to call:
Led 1 – “cold” Cheapest, size 20x20 mm, aluminum backing 1 mm.
Led 2 – “warm” Cheapest, 24x24 mm, 1 mm aluminum backing.
Led 3 is a cheap loser 20x29 mm, the substrate is 1.5 mm magnetic.
Current-voltage characteristic in amperes:
Addition. They asked to measure the comparative illumination at one current. Luxmeter on a smartphone from a distance of 0.8 m. For comparison, a table lamp with a reflector is shown.
To extend the life of diodes, they need to operate at partial power.
To understand the life of LEDs, A. Guryanov’s video helped me -
The lamp body is used from a ceiling fluorescent 2x36W, size 126x16x7 cm, bought without lamps for 600 rubles.
The PS-65-R12 power supply was used from an unnecessary satellite tuner. It has an output voltage adjustment within a small range of 9-14 V and a maximum current of 5.2 A. I selected 9.75 V. At the same time, the current of each diode, taking into account the 1 Ohm equalizing resistors connected in series, turned out to be an average of 0.6 A, and the voltage is 9.22 V. The total current from the power supply is 4 A, a larger one gets very hot. The total power consumed by the LEDs was 36.88 W.
I chose 7 LEDs, fastened with M2 screws. Radiators from old motherboards and processors.
To prevent the power supply and radiators from overheating, but they heat up well, I installed an 80 mm fan and made ventilation holes. At a voltage of 9.75 V it makes little noise.
As a result, there is enough light, but there is nothing to measure the illumination, however, the smartphone shows 3050 “parrots”.
In this topic, I will tell and show you the advantages of powering LEDs at 10 watts 12 volts, from the well-known DC-DC step-down converter.
DC-DC - this means that the converter converts DC voltage to DC, and higher or lower it is designated UP - step-up DoWN- step-down.
The converters are quite versatile and can serve as both a power supply with voltage regulation and a charger.
In this topic we will talk about LEDs with a buck converter. I hasten to note that by using these converters we also reduce the consumption of LEDs from the battery or power sources. And also recently I saw that by converting the power supply downwards and reducing the output voltage, the output current increases. The opposite effect can be seen with boost converters. Here we will observe the opposite picture, increasing the output voltage, the input current will increase until the converter and the output current will decrease.
Additional information on testing 10 Watt 12 Volt LEDs.
When powering LEDs at Max voltage, even with a reduced current, the degradation time also increases. If you initially assemble and get used to the brightness the LED produces, then for a long time it will delight you with its light, while the brightness will long be equal to what it was when you first turned it on. But if you suddenly need to get more lumens from it, I recommend improving its cooling, and prepare for the fact that after some time the brightness will drop!
There is a direct dependence on how long the LED will work, and unfortunately, the time indicated by the manufacturer refers to the minimum voltage and current at which the LED operates. The minimum parameters for working with an LED lifetime can be 50,000 hours at a supply voltage of 9 Volts and a current of 500 mA. The higher the voltage and current, the lower the lifespan of the LED!
It is a very big misconception that if you set 900 mA and 12 volts or even 11 volts, the LED will do well and will work for years. Given these parameters, it wears out and its lifespan will immediately depend on its cooling system and the ambient temperature. If you ask manufacturers how long this or that LED will last, the manufacturer will immediately begin to wag and avoid a direct answer. Like, it all depends on your network, the cleanliness of the room or the temperature. But in fact, manufacturers test almost every batch of LEDs for wear selectively and can answer it directly. That in such conditions it will last so long and in such conditions for so long.
In general, when taking any LED, read between the lines. And if you’re really curious about how long it can last, assemble two stands, one according to my scheme and one according to yours, and see what happens to the brightness of the LEDs after thirty days of operation. By the way, as an option, you can do a similar test yourself. If I have time, I'll do this experiment.
Content:LEDs have long been used in various spheres of people's lives and activities. Due to their qualities and technical characteristics, they have gained wide popularity. Based on these light sources, original lighting designs are created. Therefore, many consumers quite often have the question of how to connect an LED to 12 volts there. This topic is very relevant, since this connection has fundamental differences from other types of lamps. Please note that only direct current is used to operate LEDs. It is of great importance to observe the polarity when connecting, otherwise the LEDs simply will not work.
Features of connecting LEDs
In most cases, plug-in LEDs require current limiting using resistors. But sometimes it is quite possible to do without them. For example, flashlights, keychains and other souvenirs with LED bulbs are powered by directly connected batteries. In these cases, the current limitation occurs due to the internal resistance of the battery. Its power is so low that it is simply not enough to burn the lighting elements.
However, if connected incorrectly, these light sources burn out very quickly. A rapid drop is observed when normal current begins to act on them. The LED continues to glow, but it can no longer fully perform its functions. Such situations occur when there is no limiting resistor. When power is applied, the lamp fails in just a few minutes.
One of the options for incorrect connection to a 12-volt network is to increase the number of LEDs in the circuits of more powerful and complex devices. In this case, they are connected in series, based on the battery resistance. However, if one or more light bulbs burn out, the entire device fails.
There are several ways to connect 12 volt LEDs, the circuit of which allows you to avoid breakdowns. You can connect one resistor, although this does not guarantee stable operation of the device. This is due to significant differences in semiconductor devices, despite the fact that they may be from the same batch. They have their own technical characteristics, differing in current and voltage. If the current exceeds the rated value, one of the LEDs may burn out, after which the remaining light bulbs will also fail very quickly.
In another case, it is proposed to connect each LED with a separate resistor. It turns out to be a kind of zener diode that ensures correct operation, since the currents become independent. However, this scheme turns out to be too cumbersome and overly loaded with additional elements. In most cases, there is nothing left to do but connect the LEDs to 12 volts there in series. With this connection, the circuit becomes as compact as possible and very efficient. For its stable operation, care should be taken to increase the supply voltage in advance.
LED Polarity Determination
To solve the question of how to connect LEDs to a 12 volt circuit, you need to determine the polarity of each of them. There are several ways to determine the polarity of LEDs. A standard light bulb has one long leg, which is considered the anode, that is, the plus. The short leg is the cathode - a negative contact with a minus sign. The plastic base or head has a cut indicating the location of the cathode - minus.
In another method, you need to carefully look inside the glass bulb of the LED. You can easily see the thin contact, which is a plus, and the flag-shaped contact, which, accordingly, will be a minus. If you have a multimeter, you can easily determine the polarity. You need to set the central switch to the dialing mode, and touch the contacts with the probes. If the red probe touches the positive, the LED should light up. This means the black probe will be pressed to the minus.
However, if the light bulbs are incorrectly connected for a short time with the wrong polarity, nothing bad will happen to them. Each LED can only work in one direction and failure can only occur if the voltage increases. The nominal voltage value for a single LED is from 2.2 to 3 volts, depending on the color. When connecting LED strips and modules operating at 12 volts and higher, resistors must be added to the circuit.
Calculation of LED connections in 12 and 220 volt circuits
A separate LED cannot be connected directly to a 12V power source because it will burn out immediately. It is necessary to use a limiting resistor, the parameters of which are calculated using the formula: R= (Upit-Upad)/0.75I, in which R is the resistance of the resistor, Upit and Upad are the supply and drop voltages, I is the current passing through the circuit, 0.75 - LED reliability coefficient, which is a constant value.
As an example, we can take the circuit used to connect 12-volt LEDs in a car to a battery. The initial data will look like this:
- Upit = 12V - voltage in the car battery;
- Upad = 2.2V - LED supply voltage;
- I = 10 mA or 0.01A - current of a separate LED.
According to the formula above, the resistance value will be: R = (12 - 2.2)/0.75 x 0.01 = 1306 ohms or 1.306 kohms. Thus, the closest would be a standard resistor value of 1.3 kOhm. In addition, you will need to calculate the minimum resistor power. These calculations are also used when deciding how to connect a powerful LED to 12 volts there. The actual current value is preliminarily determined, which may not coincide with the value indicated above. For this, another formula is used: I = U / (Rres. + Rlight), in which Rlight is the resistance of the LED and is defined as Up.nom. / Inom. = 2.2 / 0.01 = 220 Ohm. Therefore, the current in the circuit will be: I = 12 / (1300 + 220) = 0.007 A.
As a result, the actual voltage drop of the LED will be equal to: Udrop.light = Rlight x I = 220 x 0.007 = 1.54 V. The final power value will look like this: P = (Usupply - Udrop)² / R = (12 - 1.54)²/ 1300 = 0.0841 W). For practical connection, it is recommended to increase the power value slightly, for example to 0.125 W. Thanks to these calculations, it is possible to easily connect an LED to a 12 volt battery. Thus, to properly connect one LED to a 12V car battery, you will additionally need a 1.3 kOhm resistor in the circuit, the power of which is 0.125 W, connecting to any contact of the LED .
The calculation is carried out according to the same scheme as for 12V. As an example, we take the same LED with a current of 10 mA and a voltage of 2.2V. Since the network uses alternating current with a voltage of 220V, the calculation of the resistor will look like this: R = (Up.-Up.) / (I x 0.75). By inserting all the necessary data into the formula, we get the real resistance value: R = (220 - 2.2) / (0.01 x 0.75) = 29040 Ohm or 29.040 kOhm. The closest standard resistor value is 30 kOhm.
Next, the power calculation is performed. First, the value of the actual consumption current is determined: I = U / (Rres. + Rlight). The LED resistance is calculated using the formula: Rlight = Up.nom. / Inom. = 2.2 / 0.01 = 220 Ohm. Therefore, the current in the electrical circuit will be: I = 220 / (30000 + 220) = 0.007A. As a result, the actual voltage drop across the LED will be as follows: Udrop.light = Rlight x I = 220 x 0.007 = 1.54V.
The formula is used for determination: P = (Upit. - Upad.)² / R = (220 -1.54)² / 30000 = 1.59 W. The power value should be increased to the standard 2W. Thus, to connect one LED to a 220V network, you will need a 30 kOhm resistor with a power of 2W.
However, alternating current flows in the network and the light bulb will burn in only one half-phase. The light will flash quickly at 25 flashes per second. For the human eye, this is completely invisible and is perceived as a constant glow. In such a situation, reverse breakdowns are possible, which can lead to premature failure of the light source. To avoid this, a reverse directional diode is installed to ensure balance in the entire network.
Connection errors