Hi guys. In this article, we are going to discuss a very simple metal detector circuit using IC 555. The circuit also uses some other active and passive components with IC 555, like coil and Buzzer for the indication and alert. So, let’s get started with our metal detector circuit using 555 IC.
There are different types of metal detectors already available like
- Walkthrough metal detector,
- Handheld metal detector &
- Ground search metal detectors.
Metal detector circuits are not that complex devices and the one we are discussing below is a basic one but cool Hand Held type.
Metal detector circuit diagram
- IC 555
- C1 1nf Capacitor
- C2 2u2(2.2uf) NPC Capacitor
- C3 10uf NPC
- C4 2u2(2.2uf) NPC Capacitor
- R1 47K
- 0.2-0.5mm Magnet wire/Copper enamelled(Motor winding wire) ,300turns & 6 cm diameter of coil
- Battery 9v or 5V
- Speaker 8R, 8ohms speaker 0.5Watts
In the circuit above, the 10mh inductor ( or coil 300 turns with 6cm diameter) i is used for the purpose of metal detection.
The IC 555 here is configured as a multi-vibrator to vibrate at a specific frequency normally and this drives the output speaker for the purpose of indicator.
Usually, there is always a normal sound coming from the speaker of 8 ohms, which indicates no metal. The inductor generates a magnetic field due to the clock output from the circuit fet to it.
Whenever a metallic substance or a magnet is brought near the coil, this is a frequency intervention & also inductance decreases which changes and alters the frequency at which the IC was operating earlier.
This change in the frequency will make will make the speaker to sound at a different tone than the usual which it was creating.
So, this is how metal detectors can detect and indicate the metals.
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