Mini Metal Detector – Kit

Description

This kit lets you build a small metal detector capable of detecting metallic objects at a maximum distance of 5 cm. Power supply: 3 to 9 VDC, dimensions (mm): 66x61x15, trimmer for adjusting the detection distance.

Operation

Once you have completed the soldering, trimmed the excess leads, and verified that everything is in order, you can already use your metal detector, since the only calibration, that of the trimmer, is done “in the field,” i.e., by bringing the circuit (powered with a 9V battery) close to metal parts and turning the cursor until you hear the sound from the buzzer. In fact, the trimmer can also be adjusted with instruments, specifically with an oscilloscope, by connecting its probe between ground (negative supply) and the collector of transistor Q1 and checking when, by turning the trimmer cursor, the sine wave corresponding to oscillation develops (if the circuit does not oscillate, the collector will have a constant potential…) and trying to obtain the maximum amplitude.