[brain]

Originally Posted by liudengyuand

I successfully detected a copper coin with a diameter of 2 cm, buried for 6 years, at a distance of 4 meters, and a depth of 30 cm, but the output of lm358 is unstable. As time increases, the machine always automatically alarms to prove the sensor The output voltage is rising automatically, so I have to adjust the critical point of 358 frequently.

Did you find it with the circuit diagram I sent?