Making a coil

The coil is wound on an oval mandrel glued from corrugated cardboard. Every ten turns are coated with epoxy resin, there are 50 turns in the coil in total, the wire diameter is 0.3 – 0.5 mm. The length of the coil is 24 cm, the width is 16 cm. After the epoxy resin has hardened, the coil is released from the mandrel, excess resin is carefully cut off, the coil is wrapped with one layer of insulating tape.

Coil shielding

The coil is wrapped with strips of aluminum foil from chocolate (screen) over the insulating tape. It is necessary to leave a small gap between the beginning and the end of the winding in the area of ​​the coil terminals (the beginning and the end of the coil screen should not be connected). Several turns of tinned wire are wound over the screen; it will be soldered to the minus of the generator board. Two layers of insulating tape are wound very tightly over the screen and tinned wire.

Making a mold for filling a coil with epoxy resin

Based on the dimensions of the finished coil, the sensor frame is cut out of fiberboard, and cardboard sides are glued to the frame. The ears for attaching the sensor to the metal detector rod are also cut out of fiberboard.

Making a generator

The generator is assembled on a piece of single-sided breadboard according to the diagram.

Filling the coil with epoxy resin

A coil and a connecting cable passed through a cable entry (PG7) are soldered to the generator. Then everything is placed in a mold for pouring, the ears and cable entry are glued with glue. It is advisable to shield the generator from below, for this purpose a piece of one-sided foil-clad textolite can be placed under the generator, the foil of which must be connected to the minus. When the glue dries, the mold is filled with resin.

After the resin has hardened, the sensor is freed from the cardboard sides and processed with sandpaper. Then you need to cover the ears and the bottom of the sensor with resin.