Homemade Metal Detector Kit

  
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A simple home project can turn catastrophic fast if you come up against an electric cable, gas and water pipes, or your central heating system. With a handy metal detector you can check beforehand whether there are metal objects in a wall, ceiling or floor. An LED indicates if a metal object is in the vicinity and keeps your simple home projects,
Homemade Metal Detector Kit - schematic

simple and safe. When wrapping the coils, do not worry about looks. There is not enough room on the core to keep the coils from overlapping. However, make sure you wrap each one in the same direction. When you solder the coil onto the PC board, make sure to strip the insulation off the ends of the coil. Either a razor blade or a fine-toothed file works great for this. For this kit, there are two types of diodes: Silicon (P/N 179215) and Zener (P/N 782788). Because they look the same, read the outer casing to be sure that you are putting in the right diode. The silicon diode has 4148 on it, while the Zener`s casing reads 3V9. I mistakenly exchanged the diodes, and it took a lot of time to figure out I had put them in the wrong holes. Also, make sure to match up the band on the diode to the band on the silkscreen. If you suspect a misplaced or bad diode, measure the forward voltage drop across them, which should be about 0. 6V for each diode. The reverse breakdown voltage for the Zener diode should be about 3. 9V. Be sure to match the flat side of the LED with the flat side in the picture on the silkscreen. Since it can be hard to see the flat side, the short lead on the LED indicates the flat side. If the LED is not turning on, measure the voltage drop across the LED. If it is 0 Volts, you probably have put the LED in the wrong way. The Metal Detector Kit needs a case, especially if you plan to move it around. I chose a...



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