Infrared illumination makes it possible to arrange such illumination of an object, which is invisible to the ordinary eye, but is well distinguishable when using night vision devices, video cameras (including security cameras), digital cameras, telephones with cameras and other similar devices.
Instructions
Step 1
Take a Chinese lantern based on about fifteen white LEDs. Remove the batteries from it. Then disassemble the device, taking care not to rip off any conductors (in this technique they are very thin).
Step 2
Find the resistor in series with the board that houses the LEDs. Unsolder it and measure its resistance. Then replace it with another one that has twice the resistance and power.
Step 3
Determine where the white LED has the cathode and where the anode is. To do this, after sketching the internal structure of any diode and its location relative to the board, unsolder it. Using the battery from the motherboard, determine where the anode is and where the cathode is. Sketch its pinout. Do not short circuit this battery.
Step 4
Buy infrared LEDs in the same housings and in the same quantity. Determine their pinout in the same way, this time using a half-discharged battery, and check the presence of a glow using a mobile phone with a camera.
Step 5
Now, observing the polarity, replace all white LEDs in the flashlight with infrared ones. Solder the white LEDs carefully so as not to damage them. Use them later in other designs.
Step 6
Install batteries in the flashlight. Turn it on, illuminate the space with invisible rays, and make sure with the same phone that it is really lit. Remember that although infrared radiation is much safer than ultraviolet radiation, you cannot direct such a flashlight directly into the eyes.
Step 7
Why use such a device? If you equip it with a stabilized power supply connected instead of batteries, it will come in handy for night illumination of the room where the security video camera is installed. She will be able to "see" in the dark no worse than in the light. Also try to photograph this or that object only under the light of such a flashlight. It will look slightly different than under normal lighting. Finally, when playing paintball in the dark, such a flashlight, combined with a camera phone, will serve as an impromptu night vision device.
