7 Conclusion

This application demonstrates the capabilities of the OPA found on the PIC18-Q71 family of devices and the other peripherals used. A basic parallel circuit with a capacitance and an inductor represents the sensor used to detect metal objects.

A PWM signal is driven to the LC sensor, which produces a damping signal processed by the OPA configured in Peak Detect mode, the output being an envelope. The signal from the OPA is filtered using an RC parallel circuit so the resulting envelope will follow all the peaks of the oscillating signal. All the values used in this project are directly proportional to the external components values and their tolerances.

The solution for the metal detector can help technology enthusiasts while being used in other projects.