Simple UV Counterfeit-Money Detector

By Tom Fox
Time Required: 10 minutes

Print this Project

It seems that counterfeit money is becoming more and more widespread. To help make it harder for counterfeiters, the US Treasury Department has started inserting strips in all US paper money (except for the $1 denomination) which glow different colors under ultraviolet light. This simple project uses a UV LED to produce the necessary ultraviolet light and, although extremely inexpensive and easy to make, this project works quite well.

Steps

Step #1:

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These are the parts you need. From left to right: a 330 ohm resistor, an ultraviolet LED, a snap-on 9V battery connector, a 9V battery and some electrical tape.

Conclusion

Notice that I didn't mention anything about $100 bills! According to the Treasury Department, $100 bills should have a strip that glows red when viewed under UV light. The problem is that it doesn't seem to--at least not brightly. This is true not only with this inexpensive detector but also when powerful, sophisticated and much more expensive detectors are used. The Treasury Department says they will soon come out with a new strip that should show up better. In the meantime, you can still use this detector to make sure that the paper the $100 bill is printed on is genuine.

One more note. The UV light produced by the LED used here is harmless since it uses long-wave UV (395nm) which is of low intensity. However, like all lights, it isn't nice to shine in someones eyes!

Tom Fox

I've been designing contraptions since I was 12. One early contraption I made was designed to turn a room light on when dark, nearly burned the house down! It also stunk the house up since its selenium rectifier overheated big time which is a real no-no.

I've learned a lot since then...thank God! Since I became interested in electricity about the time I started to crave hot dogs roasted on an open fire, I went to the Illinois Institute of Technology and received a Master of Science in Electrical Engineering. After that I started to turn out the electronic contraption designs and their prototypes at a furious pace. Many of these designs I had published in many electronic magazines such as Popular Electronics, Radio-Electronics, Modern Electronics, etc. etc. etc. and I am still doing it. My aim now is to instill in the viewer an interest in electronics AND knowledge of it as well. I firmly believe interest and motivation comes before knowledge--just look at the movie "October Sky"!

5 Responses to Simple UV Counterfeit-Money Detector

tracey on March 30th, 2013 at 9:13 am said:

awesome for us party promoters
swapnil on June 9th, 2013 at 11:47 am said:

I liked the way u provide the info . . But i would like a detailed info about any perticular project . . :-)
Safety Products on August 24th, 2013 at 1:50 am said:

There are even cheap options of Fake Currency Detector which can be used for reverse engineering.Bank note, bank cheques, passport and other important documents having some security features can be checked to stop counterfeiting and forgery with such cheap options.
jetouchet on September 29th, 2014 at 7:33 pm said:

thank you.
Hsark on May 24th, 2018 at 12:29 am said:

thanks for the lovely read

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Conclusion

Tom Fox

5 Responses to Simple UV Counterfeit-Money Detector

Make: Projects

Simple UV Counterfeit-Money Detector

Parts

Tools

Steps

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Conclusion

Tom Fox

5 Responses to Simple UV Counterfeit-Money Detector

Awesome!