# How to make LED lamp with his hands

They thought about how to check the bills? There are many degrees of protection. This perforation, and watermarks, but it would have been in vain if not for special paint, visible only by irradiating a certain wavelength. At the cash register works in a similar principle. It is believed if the bill is irradiated with infrared or ultraviolet light, the image will appear. All countries in the world use similar technology. Now let's talk how to make LED lamp by yourself, and what is the connection with banknotes.

LED lamp

## How does the LED

Unlike LEDs in a narrow emission band. Try to do a simple experiment. Take a table lamp and light, holding the hand cover. The radiation heats the steel rapidly. Hand feel light, if you put it in front of a light bulb filament. Difficult to keep the glass in a few tens of seconds of work.

The lion's share of the heat is transferred to the infrared range. For the Sun this is true, but the light bulb, whose temperature is less clearly exhibits this property. Let's face it, the light of day brighter. But not everyone understands that this infrared range. This wavelengths that lie below the visible part of the spectrum - namely, red. These frequencies are high.

Plot wider at infrared lamps. Exemplary calculation: According to Wikipedia width of this region of the order of 429 THz. Visible light occupies about 400 THz. For the Sun with its high temperature according to Wien's law the radiation density is far away in the ultraviolet spectrum (high frequency, extending almost to X). For light bulbs, two amendments play a role:

1. helix temperature is relatively low. Often, this warm tones 2700 - 2800 K. In the Sun's surface temperature reaches 6000 K.
2. The graph shown in the figure, makes it clear that a good part of the spectrum (limited to the bell-shaped curve) falls on the infrared radiation.

Schedule a filament lamp spectrum

We come to the conclusion that light - faded like the sun. Energy is wasted. Efficiency filament bulb by definition is low. In contrast, the LED strip light is relatively narrow. Based on them are made of a single frequency lasers. In the latter case, the power of the radiation is focused on a narrow strip of the spectrum. As a result, the eye perceives a higher luminance, but in reality, the radiation power is reduced.

Due to this, LED bulbs for lighting a filament similar remain cold, after hours of work. That is the reason of economy. If you make your own light from the LED tape light for less pay. Most LEDs indicate a relatively low operating voltage. Look at the photo: primotat ultraviolet LED tape feet to the battery 3 V.

Mount LEDs to the battery

## How to make the LED light source

It is important to connect properly. Breaks easily LED reverse voltage might not reach the direct worker. Can not go wrong if you become a long leg to put to positive polarity battery (flat side marked with a cross, held marking). Most of the LEDs allows operation at voltages above 3V To make light of the LED array on the USB interface, use limiting resistors. Part of the power is lost on the active resistance. The selection is carried out on the basis of the two contradictions:

• If the nominal resistance is too small, the LED will burn. By virtue of the laws of physics voltage is divided proportionally. Simply use a variable resistor and battery with a 5 V to select the desired rating for the USB bus. For the calculations give the fans and the proportion of the voltage division goes formula: U1 / U2 = R1 / R Where R1 - resistor, and R2 - resistance of the diode DC. U1 + U2 = 5 V. The latter value is variable and is determined from the current-voltage characteristics. It should be at the operating point voltage divided by the current. Feature branch is approximately a parabola.
• Too large value resistor provokes considerable ohmic losses. They are directly proportional to the resistance. Often several LEDs in series, then we should be a resistor. We can use a smaller denomination. Resistance LEDs are added, and instead of U2 will affect the amount of stress already. The probability of a short circuit is excluded in each element separately. There is no danger that falls more stress than at the beginning of operation. If only one LED burns out, turns off all branch. On the tapes is three.

LEDs of different colors

LEDs rarely closes: burning is obtained on the p-n-junction. If located in the semiconductor thicker, it makes no sense, because the glow is invisible, and is considered to be a useful part of the perimeter. Device LEDs:

1. Inside the transparent bulb, often consisting entirely of plastic or glass, it is located with a gap bridge.
2. Unequal halves. Much is about the center of "bullets" and is the cathode. Anode smaller and located on the periphery.
3. The Catcher slung thin thread. At the tip, attached to the cathode, formed p-n-junction, viewed from all directions. Thin vein is not an obstacle to free passage of light.

By virtue of such a structure of LED ill keep reverse voltage. p-n-transition is so small that it easily breaks. Why can not we make thicker? No sense. Poor cooling conditions simply do not allow the passage of large direct current. If we increase the length of the semiconductor, it will cause an increase of resistance, which naturally increase the power allocation is in working condition. The diameter of the p-n-transition can not be increased: the efficiency drops sharply. Well, the thread must not be thick, so as not to obstruct the light.

Select the middle between the efficiency and rationality. If the LED to operate at a higher voltage, then gradually he will go out and burn. Melted material p-n-transition due to poor cooling conditions.

Please note, for this reason, the semiconductor layer, and trying to make thinner. LED to work longer, made of platinum electrodes. Expensive and impractical, but also filament bulbs with this started (contacts made of precious metals).

## lamp calculations

First we find the power source. For example, USB connector or a special socket with Chinese inverter. In our view, it is out of date and no interest. Is much more efficient to find a converter to 12 and put it in the distribution board on DIN-rail. Voltage is not taken arbitrarily.

### Power

In this case it is easier to dial the desired power. From experience I would say that the one-bedroom apartment a standard layout for the needs of lighting consumes 100 watts. And while all the lamps are not included. Actually released 70 watts maximum. But even with such a scenario, it is impossible to find a converter 220 for 5 VDC. For 12 all the easier. We can take a module capacity of 120 watts for 4000 rubles, believe that the price will fall. Expensive, but if you remember that in the light required to pay 10 times less, the benefits are clear: already in the first year of operation, the module will be repaid, and longer warranty.

### Cartridges, lamps and benefits

Rather than wrestle with how to make LED lamp's own hand, more profitable to buy ready-made cartridges and light bulbs. Incidentally, the E27 approach, as we find in the sale of caps on the size. In such a case for the bulb 150 rubles pay more. If you take the light-emitting diode in the photo, its luminosity is almost zero at a retail price of 5 rubles. Of these lighting devices are not collected. When buying 200 pieces store sells Chip & Dip LEDs BL-L413UWC 10 rubles apiece. Frankly speaking, it's inexpensive. In a direct voltage of 2.7 V the LEDs give a luminous intensity of 10 cd. Then spend the calculation of economic feasibility.

### Economic expediency

Plus, that by replacing ordinary light bulbs to LED there is no need to change the wiring. And now the active losses decrease proportionally to consumption, around 10 times. A simple analysis shows that it is economically advantageous to do their own LED light only when there is no desire to buy an adapter for 12 V. In this case, inside the lamps have a small power converting unit. This increases the probability of failure, but it's easier replacement. The meaning of point make LED lamps in the chance to use LEDs and without limiting resistors (or small denomination). But, for example, the store Chip & Dip does not provide search capabilities on the supply voltage. LED bulbs are eliminated as meaningless to buy them for the price, as in 220, when it was purchased by the adapter for a large sum. It is revealed that is not profitable to take on 550 rubles matrix (at various sites), it lost the meaning of work. Take a cheap LEDs and do a decent light. Now let's see how to implement it.

### Engineering calculations

Characterized by an error of 30%. Even the exact formulas do not allow to obtain a unique result. Today decided to try the online calculator http://www.dled.ru/sections/ljumeny-v-kandely. Viewed online calculator simply translates between cd, which are the technical characteristics of the LEDs to the lumens. But it does not explain the difference. So we did.

1. Candela show how much radiant energy emitted by the source.
2. Lumens provide a correction for the angle in steradians.

LED lamp OnLayt

For example, it is understood that the light shines predominantly downward, its properties are characterized in lumens. For example, about 850 lumens equivalent to 75 W incandescent bulb. Using the online calculator, we find, as necessary elements to make light of the LED tape (marking includes the type of LEDs, which means that we can find and specifications) or any other raw materials. Suppose, as shown in the photo, Onlayt lamp has a limited area. Of course, there is no chance to measure precisely, but the sensations half-power angle (laid to the calculator for calculation) lies somewhere in the region of 120 degrees (at a luminance of 820 lumens).

It turned out that the intensity of the light coming out of 260 cd. This means, will require about 25 LEDs BL-L413UWC, to provide the same characteristics. And you need to spend on the substrate and the creation of the desired radiation pattern. We come to the conclusion that the creation of an industrial scale lamps personally disadvantageous. For the reason that LEDs are expensive. As a result, we come to what is beneficial to take the lamps to 220 V with the usual E27 base.

If you want to make the LED light for the aquarium, there is no need to put it inside. Just take the segment LED strip and stick the back side (the glass diodes) on the back wall. Source hardly heated, danger of fire is zero. We believe sconces make yourself are now a force to readers.

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