Secret of underground metal detector
More and more people begin to buy metal detectors, but most of them only look at its performance, detection depth and its role. The other is to understand how it works and what it works based on. Few people have asked about the detector configuration. But it's also true. It's hard for people who are not particularly professional players or in this industry to figure out these things.
Many people who buy underground metal detectors are only amateur players. They don't need to know the internal structure of so many instruments. They only need to know three aspects of the detector. First, whether the instrument can achieve the desired effect and can detect the underground treasure. The second is to know how to use, how to operate the detector and what problems should be paid attention to during operation. Third, how to keep the metal detector.
However, today we are going to uncover the bottom of the underground metal detector, that is, the internal circuit diagram of the instrument. This is a secret that few people know! Ordinary people, Xiaobian doesn't tell him.
Generally speaking, few people would like to know the circuit diagram of the detector. Only for some people who are particularly interested in this aspect, can they know its circuit diagram, understand its construction and basic principle of operation. The underground metal detector is basically composed of detection oscillator, reference oscillator, audio amplifier and other devices. The circuit diagram of the underground metal detector is shown below.
After the components in the circuit are installed, the working current of transistors vi-v3 shall be adjusted first. Adjust the resistance value of the trimmer RI so that the collector current of VI and V2 is 1mA, and that of V3 is 2mA. Then, turn the volume potentiometer RP to the position with the lowest resistance value (the volume is at the maximum state). When turning the fine tuning capacitor C3 clockwise, it will be found that the speaker will emit an audio call, and the sound frequency will change from high to low to silent, and then there will be an audio call, and the sound frequency will change from low to high. Readjust C3 to the silent point between the two audio calls. The search coil L1 shall be gradually close to the metal object (preferably the iron object), and the audio call with low frequency to high frequency shall be sent out in the loudspeaker.
OK, let's get here first today! I'm afraid we can't digest it. After all, it's too boring.