Converting the radio into a 30 cm depth metal detector

 Building a Gold Detector Using an AM Radio

Anyone, regardless of their background or knowledge in electronics, can build a simple gold and metal detector using an AM radio and a few basic components. This circuit is easy to assemble and effectively detects metals at a suitable depth. When any metal (gold or otherwise) comes close to the circuit’s coil (antenna), the radio will produce a sound indicating the presence of metal.

اقرا ايضاMetal detector using the IC 555 with the BFO system for the first time on the Internet

اقرا ايضاThe second and upgraded version of the hybrid metal detector

اقرا ايضاHybrid metal detector made first version

اقرا ايضاThe second step to making a metal detector

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Key Components of the Circuit

1. AM Radio

   • An AM band is required so that the radio can pick up the frequency emitted by the circuit when metal is nearby.

2. Coil

   • Shape: Circular
   • Diameter: Approximately 30 cm
   • Number of Turns: 7 turns
   • Wire Diameter: About 0.5 mm
   • It’s recommended to wind the coil carefully and neatly to ensure the best performance.

3. Transistor

   • You can use a BC547 transistor or similar alternatives like 2n3904, c1815, bc548, or bc550.
   • Be mindful of the pin arrangement (collector, base, emitter) for each transistor type.
4. Capacitors

   • Two 100nF capacitors
   • One 220µF capacitor
   • Alternative values may be used if necessary, such as 10nF instead of 100nF in some cases.

5. Resistor

   • One 10kΩ resistor.

6. Power Supply

   • Ranging from 3V to 6V (a suitable battery or external power source can be used).

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Assembly and Implementation

1. Preparing the Coil (Antenna)

   • Wind the copper wire into seven turns, forming a circle of about 30 cm in diameter.
   • Secure the windings firmly so they don’t move or overlap randomly.
2. Connecting the Components

   • Follow the attached schematic (the provided image) to connect the transistor, capacitors, and resistor correctly.
   • Ensure the correct polarity for the 220µF electrolytic capacitor.
   • If you use an alternative transistor, double-check the pin configuration (collector, base, emitter).

3. Connecting to the Radio

   • Bring the radio’s antenna close to the homemade coil. It’s preferable to fix the antenna so that it remains very close to the coil.
   • Turn on the radio, set it to AM mode, and choose a frequency where there is no strong (or only very weak) station to ensure a clear signal.

4. Testing the Device

   • Place a piece of metal (gold or otherwise) near the coil.
   • If the metal is close, you will hear a change in sound or a clear static in the radio, indicating metal detection.
   • You can adjust the distance between the antenna and the coil or reposition the radio to achieve better sensitivity.

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Tips and Recommendations

• It’s best to build the circuit in an area with minimal electrical noise or strong radio signals.
• Experiment by changing the radio’s position or the coil’s angle to improve detection sensitivity.
• If you use substitute transistors or capacitors, make sure the values and connections are correct.
• You can increase the number of coil turns or change its diameter for experimentation, but it’s advisable to stick to the specified values at first to ensure optimal performance.

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Conclusion
With minimal cost and readily available components, you can build a simple metal detector using an AM radio and an easy-to-assemble electronic circuit. When any metal is brought near the coil, you’ll hear a noise or static on the radio, helping you identify the presence of metals, especially gold. This enjoyable project is suitable for hobbyists and beginners, serving as a first step in understanding how metal detection circuits work.