How to Make IR Illuminators
- 1). Disassemble an LED flashlight. This may require the use of a jeweler's screwdriver.
- 2). There will be a circuit board containing several visible-spectrum LEDs. Cut them out.
- 3). Using a multimeter, determine how much electricity the visible-spectrum LEDs use. If the visible spectrum LEDs use more electricity than the IR LEDs (~2 volts), solder an appropriate resistor into the circuit. The exact numbers will vary with your particular flashlight.
- 4). Solder the IR LEDs into the severed leads from the standard LEDs.
- 5). Reassemble the flashlight.
- 6). Activate the flashlight. It will now produce IR light, which is not visible to the human eye. Test it with IR recording equipment.
Source...