The use of powerful LEDs (for example, bicycle lights)

    We all have long heard about semiconductor light sources, that is, LEDs. They are more economical, and more durable, and in general everything is very positive. But how can this help us? LED lamps (ordinary consumer with a base E27 and E14) are still quite crazy money , and completely unjustified. A little better in the field of auto lighting, there you can already order not very expensive substitutes for incandescent lampsin your car. Only while there are no particular advantages from them, except for power consumption and sometimes reliability (because many of them are poorly assembled and do not use current stabilizers). And probably the most advanced area of ​​application of high-power LEDs is flashlights and a bicycle light. Therefore, I will talk about the assembly of my bike light based on powerful LEDs. This experience can be applied in many areas, including to arrange LED lighting at home, with minimal skills in working with a soldering iron.

    In addition, as far as I know, the bike is quite popular among us IT people (judging by the bike forums). The fact that a normal headlight is necessary, I think it is clear to everyone who at least once rode in the evening. And so here is a description of my experiment two years ago. By the way, for two years, almost nothing has changed technically.But the prices for bicycle lights continue to fall slowly, and the assembly of their headlights for the sake of great savings is less and less justified .

    An approximate set of components for assembling a bicycle headlight itself. We need powerful LEDs (150 r) * the number of diodes + lenses and holders (100 r) * the number of diodes + driver to properly power the LEDs (200 r-500 r) + battery (here optional) and the case (50- ... r) + small things like wires and connectors.

    For example, from industrially produced headlights, the minimum (high-quality headlights) that you can find is: Dinotte 200L (powered by 4x AA batteries) ~ $ 90, Hope Vision 1 LED~ 97 $. They give light the same, the luminous flux of about ~ 200 lumens. I believe that 200 lumens is the minimum that you can agree on when choosing a bike light. Not so long ago, a 900 lumen headlamp appeared on a well-known site , for only $ 79. Bikers in Moscow have already tested and they are impressive. If you are interested in reviews and headlight tests, then you can look here , here and there .

    But we decided to assemble the headlight ourselves, so let's take care of our headlight. By and large, there is nothing supernatural or expensive in the headlamp. Therefore, making it yourself is not at all difficult. The most difficult part is to find a convenient building and come up with what we will feed our light from. Ideally, if you have access to the milling machine, it is better to make a case like Dinotte / Hope vision 1. And it will look very decent, and an excellent radiator. But if not, it doesn’t matter either, the main thing is that the case be metal. Since powerful LEDs emit a lot of heat when working in the brightest modes, they need a decent heat sink. In more gentle modes, the heat dissipation is certainly less, but do not forget, from the overheating of the diodes their resource is reduced more.

    And so we begin the selection of components:
    I took a simple aluminum box for CEA, by typesuch a simple and the whole body will be a good radiator. I drilled 6 holes for mounting the diodes and simply screwed them to the case, after adding a little thermal paste between the diode and the case. I made grooves for two switches and sockets for connecting power.

    Since I wanted to make the headlight more powerful, I decided to put 3 LEDs, and accordingly I need at least 12 volts to power them (3v + for the diode and the reserve). The case (holder) for the batteries was chosen as follows .

    The diodes that I selected were: P4 Seoul S42182-01LF-TST0H / Star. This scary long title contains all the information about the LED. P4 - model, Seoul - manufacturer. Next comes the bin, it is encoded: the color temperature of the emitted light and its strength in lumens, supply voltage, color, type of lens, etc. Here is a detailed description with decryption of all values ​​(for Seoul semiconductor diodes).

    Next were chosen suitable holders for the lenses themselves lens company Carclo . There are no difficulties with the holders, but it’s better to choose white ones, where they will work a little and as reflectors. Lenses for diodes vary in the angle of diffusion of light, most use collimators. If you have other needs, for example, you need to scatter light as much as possible, then you can take a lens with a large scattering angle, or with a matte finish .

    Powerful diodes are made not only by Seoul semiconductor , but also by CREE Inc. , Luxeon Philips , Edison . I chose Seoul then, because at some point it was the most effective. Over 100 lumens per watt. Now such a monster Seoul p7 900lm (90lm / watt) is already available . Essentially a quad Seoul p4. This is exactly what is used in the super bright Chinese headlight with Dealextreme. You can choose the most convenient or affordable - the choice is large.

    And so back to the diodes. These diodes give the so-called natural white light. That is, it is close to the white light. Due to the fact that while there are no sources of white light, it turns out using a phosphor. And the more white light we need, the less the light flux will be (because in fact such diodes emit blue light). Therefore, in almost all industrial headlights, pure white LEDs are used (they have more lumens), which give a bluish light (in the manner of xenon). In the descriptions on the diodes, you can find graphs of the emitted spectrum. Here is a compilation of various modifications of the Seoul P4 white diodes I have compiled:

    As you can see, natural white emits more light in the range that is most susceptible to our eyes. In addition, natural white light is better than blue, firstly, on wet asphalt and ground it is much better visible with it, and secondly, it is simply more pleasant.

    Since at that time I already had two Dinotte 200Ls, and they had pure white diodes in them, I decided to make a headlight with normal white light, having sacrificed a bit of the light flux in advance. And more about diodes, it is easier to use diodes in the performance of star, rather than emitter. Their substrate does not conduct current, and we can safely fix all the diodes on one radiator. Yes, and attach lenses to them easier.

    Here's what the star and emitter diodes look like:

    Diodes can be ordered both on or his twin brother, and in many small local companies selling LED components (two years ago I ordered everything at , now there are an order of magnitude more such companies).

    And so we dealt with the diodes, now we will figure out how to properly power them. In order to properly power the diodes, we need a stabilized current, and the driver will help us with this. Firstly, without this we won’t get its rated power and the service life will be shorter, secondly, the drivers are smarter than they allow you to choose power supplies over a wide range, and at the same time regulate the current strength at the output. All decent headlights power the diode (s) through the driver. If you can assemble the current stabilization circuit yourself, then the price of the device will greatly decrease. We will go the simple way, take a ready-made driver that will do everything for us. You can order it in the same place as the diodes, Dealextreme / Kaidomain / etc. I then chose the most advanced driver at that time (although the most expensive) LUXDRIVE Buckpack 3021-DI-1000 .

    This driver accepts up to 32 volts at the input, produces an adjustable current up to 1A, has an input for connecting a variable resistor (to change the output current and, accordingly, the brightness of the connected diodes) and is extremely easy to use. There are drivers for both alternating current and for operation from a 220v network - for all occasions. So you can use LED light anywhere right now, including making light in an apartment for example. If you are going to power diodes from a battery or accumulators, do not forget about a small margin, so that 2-3 volts more than you want to get at the output.

    The final layout of the headlights:

    Where is what the layout in the body:

    A few words about connecting diodes, it is better to connect in series, since the diodes still have slightly different characteristics and with parallel connection unpleasant nuances in operation are possible.

    Here is a comparison with two Dinotte 200L headlights ~ 400 lumens and this makeshift headlight ~ 500 lumens. On the left is this home-made headlight (natural white diodes), lenses with a 15 degree angle, on the right 2 x Dinotte 200L (pure white diodes), lenses with an angle of 7 degrees. The white balance in the camera is fixed.

    That's practically all that can be said about the use of powerful diodes. It’s really simple, even a beginner can assemble a circuit with a ready-made driver, literally, you need to connect the diodes with the wiring - the driver is the power source. Now the number of ready-made solutions (modules) can already satisfy almost all needs. For example, acriche seriesfrom Seoul semiconductor, connects directly to a 220v network. There are also many solutions from other manufacturers.

    If something is incomprehensibly written - ask, I will try to answer and explain. The article turned out to be a long one, so errors are inevitable (I checked it a couple of times, of course), write to the PM if something goes wrong.

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