Synopsis
Pulse Induction (PI) metal detector systems send a short pulse to the search coil instead of a continuous sine or triangle wave. Because of this working principle, they differ from continuous wave
systems. When the switch driving the system turns off, a high-amplitude flyback voltage occurs. This usually causes an unwanted ringing effect. A special damping mechanism is used to smooth this
voltage. This process puts the system’s amplitude curve into a predictable exponential decay form. The resulting signal is then sent to an analog front-end circuit to be processed. However, during this processing stage, it has been observed that temperature causes sudden jumps or drops in the signal level over time. This happens due to environmental factors and the heating of components. Solving this thermal instability problem is the main focus of this research. During the research, the effects of damping resistors on the decay curve will be examined and confirmed with empirical methods. This experimental process will include not only different resistor values but also resistors with different package types and temperature coefficients (PPM). In this way, the effects of both temperature and damping resistance on the signal will be analyzed deeply. To run the tests efficiently and make highly accurate analyses, special software will be developed. This software will show the signals graphically in the time domain in real-time and record the relevant data. As a result of the research, a final evaluation will be presented to find the ideal hardware configuration that provides thermal stability in pulse-based metal detector systems.
