Metal Detector - Inductive Sensor

At 220KHz, we can only detect metal, not the type of metal. If you want to detect different kinds of metal, use a lower frequency like 25KHz. Look at my other example: https://www.multisim.com/content/RNMyWTrr7WFxX9fh6oBFhB/metal-type-detector/ The Demodulator Circuit on the right has an idle DC voltage sitting on it. When metal comes close to the LC Tank, it will disturb the Resonant Frequency. A change in frequency will also affect the voltage amplitude. The voltage amplitude is what we are monitoring with the Demodulator. Metals will decrease the voltage amplitude. The difference in voltage is very little, so, we have to monitor it with a Microcontroller or a Comparator.