False Money and Documents Detector (ART396E)

Here is a device that the modern detective or spy who deals with documents and money: a fake documentary and money detector with ultraviolet radiation.

   Originally this article from the 80's was part of one of my spy books having been updated to a current issue.Today you can use UV LEDs in the same application.


   The operating principle is simple: illuminating the document or money with ultraviolet light and it is possible to emphasize details and the water line itself that are invisible with normal illumination.

   The device also helps detect fingerprints of people touching marked objects in cases of abductions, for example.

   It is enough to "smudge" the money from a sequestration with strontium salts, which then mark the fingers of people who manipulate it by illuminating the fingers of persons detained with ultraviolet radiation of the apparatus described, the fingers become fluorescent, as undeniable proof of the crime.

   See that the apparatus we describe works with low intensity, "black light" type radiation used in parties and dances and is totally harmless.

   The circuit consists of a battery operated inverter that powers a 2 to 7 watt bulb, depending on the availability of the assembler.

   In figure 1 we have the complete inverter diagram for ultraviolet lamp.


Figure 1 - Inverter diagram
Figure 1 - Inverter diagram


   The transformer has a 110/220 V or 220 V winding because the 110 V outlet is off, and the secondary is 6+ 6 V with a current between 250 and 500 mA.

   The transistor must be mounted on a heat radiator and the trimpot must be adjusted to obtain greater efficiency or intensity of radiation with the lamp used.

   To test the device, light up in the dark a sheet of plain paper and some plastic buttons, which should appear "fluorescent".

   Experiment with various objects. To use, simply approach the object to be examined under ultraviolet light and turn on the unit.



Q1 - BD135 - NPN power transistor



P1 - 47 k - trimpot

R1 - 1k - resistor (brown, black, red)



C1 - 10 nF - ceramic or polyester capacitor

C2 - 47 nF - ceramic capacitor or polyester

CS - 100 uF x 12 V - electrolytic capacitor



X1 - 2 to 7 watts ultraviolet light (black light) (note: the memory damper lamps are not of high intensity - the lamps used in this unit are dark).

B1 - 4 medium or large batteries

S1 – On-Off switch

T1 - transformer - see text

Box for mounting, connectors for lamp, wires, solder, battery holder, etc.