Member #744847

Member Since: November 29, 2015

Country: United States

  • I built a counterfeit bill detector with 6 of these LEDs. Knowing that I wanted to limit the current thru the LEDs to about 12 ma. I used a 78L05 to regulate the output of an alkaline 9v battery to 5v. That way, using a 120 ohm 1/8 w resistor, the current thru each LED will remain constant over the life of the battery. At 12 ma the LEDs remain cool and are still very bright. The LEDs and regulator are soldered on a plated thru fiberglass proto board which was then mounted in a small plastic box. The box is small enough to be held in the palm of the hand. Note that in addition to the parts mentioned a .33 uF tantalum cap should be used at the input of the regulator for stability. The finished device will cause UV objects to fluoresce from a few feet away so I wouldn't recommend looking at the device for more than a few seconds. I built this device with the intent to detect bogus bills. The stripe in a good bill lights up very brightly and can be seen glowing even in ambient light.

No public wish lists :(