Abstract: A banknote validator for determining the value and authenticity of a banknote is provided. The banknote validator includes a magnetic sensor, an optical sensor, and a non-return gate. The magnetic sensor includes a magnetic circuit and an electronic circuit. The optical sensor includes a trapezoidal light guide, a broadband light source for illuminating a banknote via the light guide, and sensors for detecting light reflected from the banknote. The non-return gate includes banknote-guiding means for guiding the banknote along a banknote path and for controlling the direction of the banknote's travel based on its acceptability.