INVERTING AND NON � INVERTING OPERTIONAL AMPLIFIER
AIM:- To study the operational amplifier made up of,
(1) Inverting Amplifier,
(2) Non-Inverting Amplifier.
APPARATUS:-
Sr.No. Item Requirement Remark
1. Operational Amp. 1 To perform expt.
( A 714 C ) with
output Amp.
Transistor chs.
2. Power supply 1 To supply power
3. Digital voltmeter 1 To measure voltage
THEORY: -
An operational amplifier is a direct-coupled high gain amplifier usually consisting of one or more differential amplifiers and usually followed by a level transistor
And an output stage.
The operational amplifier is a versatile device that can be used to operational
Amplifier is used to perform mathematical functions as addition, subtraction, multiplication, and intigration, comparison, Inversion etc. Thus the name �Operational Amplifier steams from its original use for these mathematical operations and is abbereviated to op-amp. with the addition of suitable external feedback components, the modern day op-amp. can be used for a variety of applications, such as ac & dc signal active filters, oscillators, comparators, regulators, etc.
The 741 is available in all three package types; 8p in metal ( an, 10-pin flat pack & 8 or 14-pin DIP ).
� Application of op-amp. as Non-Inverting Amplifier.
(a) Non-inverting amplifier with feed back.
Non-inverting configuration: -
In above ckt, In op-amp. Pin No. 3 is Non-inverting terminal. Input voltage is applied at Pin No. 3 Rf is feed back resistance.
R1 is grounded & connected to inverting terminal.
V1 = (R / 2) / [R+(R / 2) ] .Va + (R / 2) / [R+ (R / 2)] . Vb
+ (R / 2) / [R+ (R/2)] . Vc
Application of op-amp. as Inverting amplifier.
In the figure, In op-amp. Pin No.2 is inverting terminal. Input voltage is applied at Pin No. 2 . Rf is feed back resistance.
The resistance is ground to reduce the Input bias current that resistance is called as Rom ( offset minimizing resistance).
To verify the function of ckt. , we used a output voltage Vo. Which is obtained from Kirchoff�s current eqn.
Ia + Ib + Ic = IB +IF.
Since, Ri & A of the op-amp. are ideally infinity, IB = OA & V1 = V2 = 0V.
Va/Ra + Vb/Ra + Vc/Rc = -Vo/Rf
Or,
Vo = - ( Rf/Ra x Va + Rf/RbxVb + Rf/Rc x Vc )
i.e. Vo = -Rf/R1 x V1
PROCEDURE:-
1) First of all, to reduce voltage drop at i/p adjust the OFFSET null point to make it equal to zero.
2) For Inverting O/p:- Ground the Non-inverting resistance feedback resistance at inverting resistance one to determine the I/p voltage.
After to determine I/p voltage then that wire take over on the O/p terminal to
Note down the O/p voltage.
3) For Non-inverting O/p :- Ground the inverting resistances & feedback resistance and grounded . Apply the voltage at Non-inverting resistance one by one to determine the I/p voltage. After determine the I/p voltage, then that wire takeover on the O/p terminal to notedown the O/p voltage.
OBSERVATION TABLE: -
1) For Inverting Op-Amp.
Sr. No. Vin (mv) Rf Ri Vo Gain
2) For Non-Inverting Op-Amp.:-
Sr. NO. Vin Rf Ri Vo Gain
CONCLUSION:-
To perform this experiment, In inverting Op.-Amp. the amplifier gain of the O/p is given by the ratio (-Rf/Ri)
In Non-inverting Op-Amp., the amplifier gain of the O/p is given by the ratio,
(1+Rf/Ri)..