The strength of the magnetic field is directly proportional to the current flowing through the TX coil. To achieve "high power," the circuit must drive the coil with higher current pulses or higher voltage amplitudes.
This is the most common DIY approach. By using high-current driver transistors (MOSFETs) and larger diameter coils (10 to 15 inches), a standard VLF circuit can be modified for high power. high power metal detector circuit
The coil serves as the primary interface with the ground. High-power systems require wire gauges capable of handling the intended current. Generally, larger coils can provide greater depth but may be less sensitive to smaller objects. 4. Signal Processing The strength of the magnetic field is directly
A high power circuit is the only choice for "diving detectors." Pot the entire circuit board in epoxy or silicone sealant and house it in a PVC tube. Generally, larger coils can provide greater depth but
VLF circuits use continuous sine waves instead of pulses. They utilize two coils: a transmitter coil and a receiver coil.
| Type | Power Handling | Depth Potential | Complexity | |------|----------------|----------------|-------------| | | Excellent (can use high voltage pulses) | Best for deep, large objects | Medium-High | | IB (VLF) | Moderate (limited by TX amplifier) | Good for coins/relics | Medium | | BFO | Low | Very low | Not recommended |
| Component | Recommended Spec | Why | |-----------|----------------|-----| | | IRF840, IRFP460 (500V, 20A+) | Switching high voltage to coil | | Flyback diode | Fast recovery, 600V, 10A+ | Protects MOSFET | | TX Coil | 300–500 µH, 0.5–1.0 mm² wire, 25–30 cm diameter | Handles high current | | TX Voltage | 50–150 V DC (boost converter from 12V) | More power → deeper detection | | RX Coil | 100–300 µH, fine wire (0.2 mm), shielded | High sensitivity | | Op-amps | NE5534, TL081 (low noise) | Signal amplification | | Microcontroller | Arduino Nano, STM32 | Pulse timing & audio out |