Electrical Comparators
Electrical Comparator
An electrical comparator consists of the following
three major part such as
1) Transducer
2) Display device as meter
3) Amplifier
Transducer: An iron
armature is provided in between two coils held by a leaf spring at one end. The
other end is supported against a plunger. The two coils act as two arms of an
A.C wheat stone bridge circuit.
Amplifier: The amplifier
is nothing but a device which amplifies the input signal into magnified output
Display device or meter: The amplified
input signal is displayed on some terminal stage instruments. Here, the
terminal instrument is a meter.
Working principle:
If the armature is
centrally located between the coils, the inductance of both coils will be equal
but in opposite direction with the sign change. Due to this, the bridge circuit
of A.C wheat stone bridge is balanced. Therefore, the meter will read zero
value. But practically, it is not possible. In real cases, the armature may be
lifted up or lowered down by the plunger during the measurement. This would
upset the balance of the wheat stone bridge circuit.
Due to this effect, the
change in current or potential will be induced correspondingly. On that time,
the meter will indicate some value as displacement. This indicated value may be
either for larger or smaller components. As this induced current is too small,
it should be suitably amplified before being displayed in the meter.
