Ever wondered what happens when you insert a bill into a vending machine? [Janne] is back with his latest project: reverse engineering a banknote validator. Curious about how these common devices work, he searched for information but found few resources explaining their operation.
To learn more, [Janne] explored the security features that protect banknotes from counterfeiting. These can include microprinting, UV and IR inks, holograms, color-shifting coatings, watermarks, magnetic stripes, and specialty paper. These features not only deter fraud but also enable validators to quickly verify a bill’s authenticity.






