Simple Metal Detector Circuit using IC 555

This simple to assemble metal detector circuit makes use of the IC 555, a widely available chip.

Despite its various uses, this IC 555 chip functions as a miniature clock in this application producing a signal that aids in the detection of metals and magnets.

Circuit Working:

Parts List:

In this article simple metal detector creates an oscillating magnetic field with a IC 555 integrated circuit.

The magnetic field is broken when metal is introduced close to the coil, changing the frequency of oscillation.

A speaker detects this shift in frequency and generates a tone.

The circuits working are mentioned below:

The configuration of the 555 IC is that of an astable multivibrator.

It produces a square wave output at pin 3 while in this mode.

The settings of resistor R1 and capacitor C1 define the square waves frequency.

A timing network made up of capacitor C1 and resistor R1 regulates the oscillations frequency.

The speaker will emit an audible tone at the settings shown in the diagram above..

As a decoupling capacitor, capacitor C2 aids in preventing noise from interfering with the circuits ability to function.

A wire is twisted around a shape to create a coil.

A magnetic field is produced when electricity passes through it.

The diameter of the coil and the number of wire turns will determine the oscillation frequency.

The speaker emits a tone when the oscillations frequency shifts.

The closer metal gets to the coil, the higher the pitch of the tone.

Formulas:

The IC 555 in astable multivibrator mode may be used to build a metal detector circuit that produces an oscillating electromagnetic field.

Metal items can be recognized because they alter the oscillation frequency when they interfere with this field.

Here is the formula take into account while creating a circuit of such kind:

Formula for Frequency (f):

The following formula provides the frequency of oscillation (f) in an astable multivibrator circuit that uses an IC 555:

f = 1.44​ / (R1+2×R2) × C

where,

• R1 and R2 are the resistors connected to the IC 555.
• C is the capacitor connected to the IC 555.

For the purpose of creating an astable multivibrator circuit employing an IC 555 in a metal detector application, the formula is imperative.

It makes it possible to compute and modify the oscillator frequency, which fluctuates in reaction to environmental changes brought on by the presence of metal objects.

By modifying R1, R2, C and the coils properties the sensitivity and metal detecting capabilities of the circuit may be maximized.

How to Build:

To build a Simple Metal Detector Circuit using IC 555 below mentioned are the steps for connections:

• Gather all the components as mentioned in diagram.
• Connect pin 1 of IC 555 to ground.
• Connect pin 2 of IC 555 to pin 6.
• Connect pin 3 of IC 555 to ground through capacitor C1 and 8 ohm speaker.
• Connect pin 4 of IC 555 to positive of 6V to 12V.
• Connect pin 6 of IC 555 to one end of resistor R1 and other end to positive supply.
• Connect capacitor C2 to ground from pin 2 of IC 555.
• Connect a coil 10mH and a capacitor C3 between pin 2 and pin 6 of IC 555.
• Connect pin 8 of IC 555 to positive supply of 6V to 12V.

Additional Note:

• The circuit is susceptible to changes in the ground.
• To identify a favorable operating point, resistor R1s value may need to be adjusted.
• Increase the value of capacitor C1 or use a bigger coil to make the circuit more sensitive.
• But doing so will also increase the circuits sensitivity to noise.
• Due to its simplicity this circuit is unable to distinguish between various metal kinds.

Conclusion:

To conclude, this metal detector circuit provides a basic overview of metal detection its sensitivity and capacity to distinguish between different metals.

The 555 IC is used in the metal detector circuit to provide an oscillating signal that is disturbed by metal objects in the vicinity enabling the circuit to detect their existence.

References:

Metal detector