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CIRCUIT · BFO METAL DETECTOR

BFO Metal Detector Circuit Diagrams

Explore BFO (beat frequency oscillator) metal detector circuit diagrams—from simple two-oscillator designs to high-sensitivity builds with op-amps and audio amplifiers. These examples show how the search coil, reference oscillator, mixer, and audio stages connect to detect metal objects.

3 EXAMPLES· UPDATED 2026-09-12
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METAL DETECTOR

BFO Metal Detector with LM339, 7805, BF422

High-Sensitivity BFO Metal Detector

ELECTRONICS

Simple BFO Metal Detector Using Two 555 Timers and LM386

ABOUT

About these examples.

Whether you're a hobbyist, electronics student, or builder, these schematics give you a working reference. Use the generator below to start from a template or build your own BFO metal detector circuit diagram from scratch.

HOW TO

Make one yourself.

  1. 1

    Choose a BFO detector template

    Start with a pre-built BFO metal detector circuit diagram or open a blank canvas.

  2. 2

    Add oscillator and mixer stages

    Drag components for the search coil oscillator, reference oscillator, and mixer onto the canvas.

  3. 3

    Wire the signal path

    Connect the oscillator outputs to the mixer, then route the difference signal through a low-pass filter and audio amplifier.

  4. 4

    Set component values and labels

    Adjust resistor, capacitor, and coil values, and label test points for troubleshooting.

  5. 5

    Export or share

    Download the circuit diagram as an image or PDF, or share a live link.

FAQ

Frequently asked questions

What is a BFO metal detector circuit?01
A BFO metal detector uses two radio-frequency oscillators—a search coil oscillator and a fixed reference oscillator. When metal changes the search coil's inductance, the beat frequency between the two oscillators shifts, producing an audible tone change.
Can I build a BFO metal detector from these diagrams?02
Yes. The examples show complete component-level schematics. You can copy a design or modify one in the generator to match your parts and coil specifications.
What components are commonly used in BFO metal detectors?03
Typical designs include transistors or op-amps for the oscillators, a mixer stage, a low-pass filter, and an audio amplifier. Common ICs include 555 timers, LM386 audio amplifiers, and dual op-amps like LM358 or LM339.
How do I make my own BFO metal detector circuit diagram?04
Use the generator on this page. Pick a template, add or replace components, wire the stages, and adjust values—all in your browser.
Are these circuit diagrams editable?05
Yes. Every example in the gallery can be opened in the editor, modified, and saved as your own.
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