Metal Detector Security Inspect Instrument Science Technology Experiment DIY Kit

Package include:
1 x Metal Detector DIY Components Kits

This is metal detector circuit board electronic DIY Components kits, this item can detect any metal,coin,stainless any thing which was made by the metal,about 2.5-4cm distance for sensor to detect the metal depend on how big of metal, if it is small size, it can detect about 2.5cm, example coin.

Specifications:
Model:5098
Name:Metal Detector DIY kits
1.Power Supply :3 * 1.5V AA DC (NOT INCLUDE )
2.Detection distance:2.5-4cm depend on size of metal
3.Buzzer alarm when sensor can detect the metal

Note:
1.Away from the metal,it should stop voice,if no,you should adjust a little by potentiometer anticlockwise direction and try it again.
2. Change a little C5 capacity can be changed the frequency of the voice.

Operating principle:
1.Q1, L1, L2, C2, C3, R1, W compose high-frequency oscillation circuit, adjusting the potentiometer W, can change the oscillation gain, the oscillator is in the critical state of oscillation, that is to say, just make the oscillator start up.
2.Q2, Q3 detection circuit,when the circuit normal oscillation, Q2 conduction, Q3 stop; When detecting coil L1 near the metal objects, can produce eddy currents in metal conductors, make energy loss increases from the oscillating circuit, the positive feedback is abate, oscillation in the critical state of the oscillator is abate, even it can't maintain the minimum energy required for oscillation and vibration, make Q2 stop, Q3 conduction, for Q4, Q5 audio oscillator circuit of power supply work, push a buzzer and make a sound.
3.With sound or without sound, you can determine whether it has metal objects below the detection coil.