The purpose of this thesis was to design an electrical system for use in a ballistic test at the Swedish National laboratory of forensic science (SKL). The detector unit would use four main parts: coilsystem, transmitter, reciever and indicator. The coilsystem would be based on a balanced system using three coils. One that creates a magneticfield and the other two will sense the differences when a metallobject is in the coilsystem. This report starts out by investigating possible solutions for this specific task followed by a description of the physics that the metaldetector use.