Metal detector circuit diagram 3

Description: The metal detector consists of a probe oscillator, a reference oscillator, an audio amplifier, and various other components, as illustrated in the schematic. The probe oscillator is made up of transistors V1 and V2, a detection coil L1, a capacitor C1, among other components. The reference oscillator includes transistors V1 and V3, along with an inductor L2, capacitor C3, and additional components. The audio amplifier comprises an audio power amplifier IC, a volume potentiometer RP, and capacitors C6 to C8. Resistor R1 is a small or variable resistor, while resistors R2 to R5 are 1/4W metal film resistors. The potentiometer RP is a small membrane type. Capacitor C1 is a high-frequency ceramic capacitor, capacitors C2, C5 to C8, and C10 are aluminum electrolytic capacitors rated at 10V, capacitor C3 is a ceramic fine capacitor, and capacitors C4 and C9 are polyester or monolithic capacitors.

The metal detector circuit is designed to detect metallic objects by utilizing a combination of oscillators and amplification stages. The probe oscillator generates a varying electromagnetic field through the detection coil L1, which interacts with nearby metallic objects. The resulting changes in the oscillation frequency are detected and processed by the reference oscillator. The reference oscillator, comprising transistors V1 and V3 along with inductor L2 and capacitor C3, stabilizes the frequency and provides a reference signal against which the probe oscillator's output can be compared.

The audio amplifier section, which includes an audio power amplifier IC, serves to amplify the audio signal generated by the detection process. The volume potentiometer RP allows for adjustment of the output audio level, ensuring that the user can hear the detected signals clearly. Capacitors C6 to C8 are employed to filter and stabilize the audio signal, enhancing the overall performance of the amplifier.

Resistors R1, R2 to R5 are carefully selected to ensure the proper functioning of the circuit. R1, being a small or variable resistor, may be used for fine-tuning the sensitivity of the probe oscillator. The 1/4W metal film resistors R2 to R5 provide stability and accuracy in the circuit's operation. The choice of capacitors, including high-frequency ceramic and aluminum electrolytic types, is critical for maintaining signal integrity and ensuring reliable performance across various operating conditions.

Overall, the metal detector circuit exemplifies a well-integrated design that balances sensitivity, stability, and user control, making it an effective tool for detecting metallic objects in various environments.The metal detector is composed of the probe oscillator, reference oscillator and audio amplifier and other components, and the circuit is shown as the chart. Probe oscillator consists of transistors VI, V2 and detection coil L1, capacitor C1 and so on. Reference oscillator consists of transistors VI, Y3 and inductor L2, capacitor C3 and other comp onents. Audio amplifier is composed of audio power amplifier IC IC, volume potentiometer RP and capacitors C6 ~ C8 RP and so on. R1 uses small or variable resistor; R2 ~ R5 select 1/4W metal film resistors. RP uses small membrane potentiometer. C1 uses high-frequency ceramic capacitor; C2, C5 ~ C8, CIO use aluminum electrolytic capacitor with the voltage in 10Y; C3 uses ceramic fine capacitor; C4, C9 select polyester or monolithic capacitors.