From the given option, the combination of input voltage 7v, 4v and -3v gives the value 9v. 5. In the circuit shown, supply voltage = ±15v, Va= +3v , Vb= -4v , Vc= +5v, R= R1= 1kΩ and RF= 2kΩ. 741 op-amp has A= 2×105 and R1= 10kΩ. Determine the output voltage internal resistance of the circuit?
A. Vo ≅3v , RiF=6.67MΩ
B. Vo ≅3v , RiF= 7MΩ
C. Vo ≅3v , RiF=9.2MΩ
D. Vo ≅3v , RiF= 3.5MΩ
Answer:A
From the given option, the combination of input voltage 7v, 4v and -3v gives the value 9v. 5. In the circuit shown, supply voltage = ±15v, Va= +3v , Vb= -4v , Vc= +5v, R= R1= 1kΩ and RF= 2kΩ. 741 op-amp has A= 2×105 and R1= 10kΩ. Determine the output voltage internal resistance of the circuit?
A. Vo ≅3v , RiF=6.67MΩ B. Vo ≅3v , RiF= 7MΩ C. Vo ≅3v , RiF=9.2MΩ D. Vo ≅3v , RiF= 3.5MΩ
Explanation: The output voltage Vo= [1 + (RF/R1)] × [ (Va+Vb+Vc/3)] = [1+(2kΩ/1kΩ)] ×[(3-4+5)/3]= 2.67 ≅ 3v.