op amps 2

The purpose of this lab is to explore further the effect of op amps on a voltage source using an inverting amplifier.

this is the circuit we are dealing with, as you can see we had to change the voltage sources to 12V sources because of availability. and the resistors used are as follows.

Resistor	Nominal Value	Measured Value
R1	10k	9.86k
Rf	100k	98.3k

we predicted the value of the current leaving the op amp to be .1mA and then built the circuit.

Vin Desired	Vin Actual	Vout Measured	Vrf Measured	Iop Calculated
0.25	0.25	-2.67	2.66	.0266mA
0.5	0.5	-4.95	4.92	.0492mA
1	1	-9.9	9.82	.0982mA

We measured

Icc=.933mA

Iee=-1.034mA

Therefore Iop=Icc+Iee

=.933-1.034

=-1.01mA

our power supplied by each of the 12V sources is

P=.0124W

P=.0112W

then we added a 1Kohm resistor

and measured

Vin Desired	Vout Measured	Vrf Measured	Iop Calculated	Icc Measured	IEE Measured
1V	-10	9.96	.1mA	.73mA	-11.09mA

KCL for the op amp continues to hold because the currents are at different values, which means it was divided through the circuit.

the new power supplied by each voltage source is

P=.133W

P=.0087W

Extra Credit

Rf=50Kohms

Vin Desired	Vout Measured	Vrf Measured	Iop Calculated	Icc Measured	IEE Measured
1V	-5.07V	5.05V	1.01mA	.932mA	-1.033mA

these measurements do behave as expected because of the change in resistor it cuts the factor of 10 down to a factor of only 5. because the resistor is half as much as before.