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 ايضا The first way to make a metal detector

اقرا ايضاConverting the radio to a metal detector very great depths

اقرا ايضا Experiment with the large coil metal detector 60*60

اقرا ايضاDetails of making the small coil of the detector, depth of 3 meters

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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.