A simple economical metal detector with your hands on one chip
If you have lost the ring, the key, the wrapper... and you know the approximate place of loss, don't despair! You can assemble a metal detector with your own hands or ask a fellow radio amateur to assemble a simple metal detector with his own hands. Below is a diagram of a simple-to-manufacture and years-tested metal detector, which (with certain skills) can be done in one day. The simplicity of the metal detector described is that it is assembled on just one very common Chip K561LA7 (CD4011BE). The setup is also simple and does not require expensive measuring devices. An oscillograph or frequency meter is enough to set up generators. If everything is done without errors and from the correct elements, then these devices will not be needed.
Sensitivity of this metal detector:
metal lid from the can "sees" up to 20 cm, cell phone up to 15 cm, battery "crown" up to 10 cm, 5 rubles coin up to 8 cm .
At this distance, the tone of the generator in the headphones barely changes, at closer distance the tone increases. The larger the metal area, the greater the detection distance. Distinguishes diamagnetics and ferromagnetics.
To make a metal detector, we will need:
Microchip K561LA7 (or K561LE5, analogue CD4011);
Transistor - low-frequency low-frequency, for example - CT315, CT312, CT3102, analogues: VS546, Sun945, 2SC639, 2SC1815, etc.);
Diode - any low-power, for example - k522B, kd105, k106, analogues: in4148, in4001, etc.;
Variable resistor - 3 pieces (1 kom, 5 kOm, 20 kom with switch or switch separately);
Permanent resistor - 5 pieces (22 Om, 4.7 kOm, 1.0 kOm, 10 kOm, 470 kOm);
Ceramic, and even better mica capacitors - 5 pc: 1000 pf -3pc, 22n -2pc, 300pf);
Electrolytic capacitor (100.0 mcff x 16B) - 1pc;
A PEL wire or PEV with a diameter of 0.6-0.8 mm;
Low-key headphones (from the player);
Battery 9B.
Metal detector scheme
