Those who used metal detectors know how convenient a pinpointer is – a small hand-held metal detector in the form of a small cylinder. Another area of ​​​​application is to look for some kind of metal artifacts in the walls (so as not to stumble on reinforcement when drilling), clean car tires from stuck nails, etc. You can also use it as a regular security inspection metal detector.

Here is a schematic diagram of a hand-held metal detector, taken from the site md4u.ru and the finished board.

For the case of a hand-held metal detector, a piece of 25 cm of a plastic plumbing pipe with a diameter of 30 mm will go. Power is supplied from the crown, the current consumption is about 15 mA. Op-amp chips are replaceable by any of the TL062, 064, 072, 074, 082, 084 series. The setting consists in selecting the mode for reliable start of the generator. With the resistors indicated in the diagram, we set the sensor, integrator and sound tone, respectively. We put a sound emitter in a manual metal detector DEMSh or small-sized from Chinese New Year’s toys.