TDA0161 metal detector electronic schematic
This metal detector circuit diagram is based on the TDA0161 monolithic integrated circuit , designed for metallic body detection by detecting the variations in high frequency Eddy current losses.
Output signal is determined by supply current changes. Independent of supply voltage, this current is high or low according to the presence or the absence of a close metallic object. Using two LEDs this circuit provide an visual indication of presence or absence at a metals around the coil . To adjust the circuit you need to make sure there is no metal near the coil and then set the fine adjustment to a "Mid position". After that you need to adjust the course adjustment to turn on the LED and , adjust the fine adjustment to turn off the LED.
This detector electronic circuit operates over a wide range input voltage of 4 -35 volts .