Metal detector using difference resonator
Abstract:
A metal detector is a device which responds to metal that may not
be readily apparent. The simplest form of a metal detector consists of an oscillator
producing an alternating current that passes through a coil producing an alternating
magnetic field.
Metal Detector using 555 Timer is a simple metal detector cyber
banking activity can be advised application a simple 555 timer chip ambit. As you
can see in the schematic ambit , this cyber banking activity requires few alien
cyber banking genitalia . This circuit detects metal and additionally magnets. When
a allurement is brought abutting to the 10mH choke, the achievement abundance
changes. This metal detector activity can be powered from a ability accumulation
that can accommodate an achievement DC voltage amid 6 an 12 volt. If a metal is
afterpiece to the L1 braid, will aftermath a change of achievement cadence
frequency that will accomplish a complete in the 8 ohms speaker.
Circuit Diagram:
For Details Contact: A.VINAY-9030333433, 0877-2261612
Block Diagram:
Sensing Coil
R.F.
Oscilator
Detector
Alarm
Working:
Working:
The metal detector can be used to detect both ferrous and non-ferrous
metallic objects. Most metal detectors use a balanced, three-coil, system to detect
small particles of non-ferrous and stainless steel. The coils are wound on a nonmetallic frame, each parallel with the other. The center coil is connected to a high
frequency radio transmitter. Coils on either side of the transmitter coil are
receivers. As these two coils are identical and placed the same distance from the
transmitter, they receive the same signal and produce an identical output voltage.
When the coils are connected in opposition, the output is cancelled,
resulting in a zero value. When a particle of metal passes through the coils of a
metal detector, the high frequency field is disturbed under one coil, changing the
voltage by a few micro volts. The state of balance is lost and the output from the
coils is no longer zero. It is this phenomenon that is used to detect metal
In this metal detector a sensing coil is given at a input. This coil forms part
of R.F. Oscillator. It generates 1.7 MHZ R.F signals. Output of oscillator is given
to detector stage. R.F signals generated by oscillator are undergone rectification
here. Rectified voltage is given to an NPN transistor which is connected to reset
For Details Contact: A.VINAY-9030333433, 0877-2261612
pin of I.C.555.Timer is wired as low frequency astable multivibrator to drive a
buzzer and an L.E.D.
When oscillator generates R.F signals reset pin of I.C.555 is held at ground
level due to conduction of transistor. Then timer gets disabled and buzzer does not
work. When a metallic object is brought near sensing coil R.F. Oscillator stops
working. Then no R.F. signals are generated. As a result transistor connected to
reset [in of I.C.555 stops conduction. Then reset pin is held at high level. Then
timer works and beeping sound is from buzzer.
Power Supply:
Step Down
T/F
Bridge
Rectifier
Filter
Voltage
Regulator
The input to the circuit is applied from the regulated power supply. The a.c.
input i.e., 230V from the mains supply is step down by the transformer to 12V and
is fed to a rectifier. The output obtained from the rectifier is a pulsating d.c voltage.
So in order to get a pure d.c voltage, the output voltage from the rectifier is fed to a
filter to remove any a.c components present even after rectification. Now, this
voltage is given to a voltage regulator to obtain a pure constant dc voltage.
For Details Contact: A.VINAY-9030333433, 0877-2261612
Applications:
 Packaging Industry
 Security Screening
 Tourist Centers
Advantages:
 It is used to detect the metals.
 Simple Circuit
 Easy operation
For Details Contact: A.VINAY-9030333433, 0877-2261612