Not so long ago I discovered super-bright LEDs for myself at a very affordable price. They look like this:
They have a lot of advantages: high brightness, relatively low energy consumption, long service life, small dimensions, resistance to repeated switching, etc. Available with a power of one watt or higher, they have three different shades of white light.
But when using them, I encountered some difficulties. Firstly, they get very hot. If you use them at least half the power, they will need a radiator. Secondly, these LEDs have a large scattering angle. That is, if you make a simple table lamp out of them, it will shine in the eyes as well as on the table. Therefore, the luminous flux must be focused in the right direction. The following construction helped solve both of these problems.
A bit of school physics. You can focus the light flux, or direct it in parallel using a parabolic mirror, if you place a point source of light in the focus of the parabola. Make a parabolic mirror in home conditions - an impossible task. But it is possible to make a plafonder, which would at the same time partially focus the luminous flux and remove heat.
The green line in the figure is a parabolic mirror, the black rectangle at the bottom is a super-bright LED, the yellow dot is the LED crystal and at the same time the focus of the parabola. And the remaining black lines are the body of the future reflector. It is clear that the body follows the shape of a parabola very approximately, but it will focus a certain percentage of light. Dimensions, of course, are indicated in millimeters.
The reflector scan will look like this:
You can make a can of aluminum from a thickness of 0.5-1mm, copper, or even tin from a can. In this case, aluminum 1 mm thick was used.
In addition, for the lamp you will need a piece of one-sided foil PCB with a size of 15x20 mm, on which the LED itself will be soldered.
To begin with, a reflector and textolite are cut out, then holes are drilled in them, 4 pieces with a diameter of 1 mm, two more holes with a diameter of 3 mm are drilled in the plafond, and two holes of 1 mm in the PCB for connecting wires. Then the reflector and the textolite are twisted together by two pieces of wire. You can still further glue them.The reflector bends, resulting in the following:
It is necessary to bend the reflector carefully so as not to deform the seat under the LED, otherwise the LED will overheat. If the reflector is made of copper or tin, then its petals can and should be soldered together. After the reflector is bent, its edges can be processed with a file or sandpaper, if necessary.
The final step is to install the LED. Before this, it is necessary to apply a little thermal paste to the place of its installation in order to improve heat transfer. The LED leads will have to be bent a little so that they crawl into the holes. After that, the conclusions are unbent to the initial state, the LED is pressed to the reflector and soldered. It is necessary to ensure that none of the contacts of the LED touches the reflector in order to minimize the short circuit between the terminals.
Everything, the mini-lamp is ready.
Small dimensions allow you to use this design as a flashlight, backlight for something, or a table lamp. By the way, the voltage of the LED is 3.2-3.4 volts, which makes it possible to power it from a USB computer or laptop. To limit the current, you can use a special driver, or simply limit the current with a resistor. For a supply voltage of 5 volts for a single-watt LED (current 300 mA), the resistance rating will be 6.2 - 6.8 Ohms, 1 W.