Introduction
A metal detector is a simple electronic device used to find metal objects. This circuit is designed using an IC (CS209A), which senses changes in the electromagnetic field caused by nearby metal. It works with a coil and a capacitor that create a tank circuit to detect changes in inductance. When metal is brought near the coil, the IC detects it and sends a signal to light up an LED and activate a buzzer. A 9V battery powers the entire circuit, making it portable and easy to use. This design is compact, efficient, and can be built with basic electronic components. It's ideal for beginners who want to understand how metal detectors work.
Components Requried
| S.no | Components | Value | Qty. |
|---|---|---|---|
| 1. | IC | CS209A | 1 |
| 2. | Resistor | 560 Ω, 1 KΩ | 1,1 |
| 3. | Capacitor | 2.2nf | 2 |
| 4. | Variable Resistor | 20 KΩ | 1 |
| 5. | Buzzer | 5V | 1 |
| 6. | LED | Green 5mm | 1 |
| 7. | Inductor(0.4mm Insulated copper, L1 has 40mm in diameter and made of 50 turns) | - | - |
| 8. | Battery | 9V | 1 |
Pin configuration of CS209
- Pin 1 (OSD): Oscillator Sense Drive – Connects to the coil and capacitor to form the tank circuit for detecting changes in inductance.
- Pin 2 (TANK): Tank Circuit Input – Connects to the coil and capacitor, working with Pin 1 to sense inductance changes.
- Pin 3 (GND): Ground – Connects to the negative terminal of the power supply for circuit grounding.
- Pin 4 (OUT1): Output 1 – Outputs a signal when metal is detected. Used to drive external components like an LED or buzzer.
- Pin 5 (OUT2): Output 2 – Another output, often unused or used for additional external indications.
- Pin 6 (DEMOD): Demodulator Output – Filters and processes signals from the tank circuit for metal detection.
- Pin 7 (VSS): Power Supply – Connects to the positive terminal of the power supply (typically 5–9V).
- Pin 8 (RF): RF Oscillator Input – Connects to the coil and capacitor, helping generate the oscillations for detecting changes in the electromagnetic field.
Circuit Diagram
Working Explaination
This is a simple metal detector circuit that uses the CS209A IC to detect metal objects. The coil and capacitor form a tank circuit that generates an electromagnetic field. When a metal object comes near the coil, the electromagnetic field changes because the metal affects the coil's inductance.
The CS209A IC detects these changes and sends a signal to the output. The circuit has a 20K variable resistor to adjust sensitivity, so you can fine-tune how close the metal needs to be for detection.
When metal is detected, the IC activates the buzzer and LED. The LED lights up, and the buzzer makes a sound to let you know metal is nearby.
A 9V battery powers the circuit, while resistors control the current flow to protect components like the LED and buzzer. The 2.2nF capacitors help stabilize the circuit.
Applications
- Security Scanners
- Treasure Hunting
- Industrial Metal Detection
- Mine Detection