Radio Constructor (Radio-Kit) Pulse Metal Detector Pirate, Clone

Description

Coin Detection Depth: 20 - 25 cm
Depth of detection of large objects: 100 - 150 cm
Supply voltage: 9 - 14 V
Power Consumption: 60 - 70 mA
Pulse current consumption: 1 - 2 A
Overall dimensions of the board: 45x52 mm
The K158 radio is intended for the manufacture of a metal detector that allows you to detect objects from ferrous and non-ferrous metals.
The device consists of two main components: transmitting and receiving. The transmitting unit consists of a pulse generator on the NE555 chip and a powerful key on the IRF740 transistor. The receiving node is assembled on a TL072 chip and a BC547 transistor. The excitation signal is transmitted periodically to the sensor coil, in the form of pulses with a duration of 125-150 μs and a frequency of 125-150 Hz. In conductive objects, damped eddy currents are induced that excite a damped electromagnetic field. Depending on the conductive properties and size of the object, the signal changes its shape and duration.
Search Coil Fabrication
For the manufacture of a search coil, a rigid non-metallic mandrel Ø 200-250 mm, a copper winding enameled PEV wire (Ø0.4 - 0.6 mm) 20 meters long, a copper stranded insulated wire 2x1.5 mm2 120 - 150 cm long for connecting the coil to board. Wrap 25 turns of winding wire tightly around the mandrel. Fix the ends of the wire and use soldering to connect the multicore insulated wire to the circuit board to the contacts L1.
Assembly and tuning of the metal detector
To the contacts SP1 solder the speaker 8 Ohms 0.5 watts.
The contacts P1 are supplied with power 9-14 V (preferably from a battery 12 V 1.2 A / h).
After turning on the device by rotating the tuning resistor R8, find the position where the clicks in the speaker are quieter as much as possible and the noise does not begin to increase, after which the resistor R9 does the same operation, but more precisely, the maximum sensitivity of the metal detector is at the threshold of sound generation.
The sensitivity of the metal detector can be improved by changing the number of turns of the coil.
With a mandrel diameter of 250 mm and a winding wire of Ø0.5 mm, this is about 14 turns.
After tuning, the coil can be rigidified by wrapping it with tape, electrical tape, or impregnating it with epoxy.
Photo may differ from the present.
But in no case is the functionality affected.
Shipping
insured from Europe with Tracking number.
Carefully package.
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