Contactless Metal Detector With Reed Contact

thingiverse

Description: This metal detector can detect metals that are magnetizable like mild steel. It has a detection distance of about 5mm to a metal sheet and can detect pinballs up to 4.5mm away. The magnets used in this design measure 5x2mm in size, which was found to be the optimal size for detecting metals. Larger magnets did not increase the detection range, while smaller ones reduced it. The presence of metal disturbs the magnetic field, causing an imbalance that activates the reed switch. These metal detectors were specifically designed to detect pinballs in pinball machines. Building: - Heat copper wires and push them into plastic sides, leaving a few mm exposed for soldering. - Push the reed switch through the center hole. If closed, use a drill to enlarge it. - Place two magnets of equal strength next to each other, ensuring they attract each other. - Test the sensor with metal; you should hear the reed switch closing and opening. Sometimes rotating the contact helps find the correct position. - Bend wires against copper and solder them in place. - Finally, push isolated wires through a side hole and solder them to copper wires. See photos of how these parts are assembled. Materials: You'll need the following components: - A 7mm or 10mm glass reed switch, such as type MKA-10110 from Aliexpress. - Two pieces of 5cm long, 1mm diameter copper wire. - Two magnets measuring 5x2mm or 5x1.8mm from Banggood. Print: ABS is used in this design, but PLA, PET, or other materials can also be employed. A fill rate of 90% to 100% works well, with no support needed.