LM 741 Questions

ElectronicTy

New Member

• Mar 8, 2018

• #1

Hi all i have a problem with a LM741 op-amp,
when calculating the output voltage i should have when inputting 12vpp using the formula Vo = Vi(1+Rf/Ri) and the values being vi = 12 rf = 6k Ri = 1.5k i should be having an output of 60v, but when building and simulating my design i only have 27.8v.
it works when i use 2vpp as the output is the exact same as my calculations.
any help would be great, below is the circuit
Thanks

 

Last edited: Mar 8, 2018

Nigel Goodwin

Super Moderator

Most Helpful Member

• Mar 8, 2018

• #2

As your supply is only 30V, how do expect the output to go higher than that?.

 

L

Les Jones

Well-Known Member

Most Helpful Member

• Mar 8, 2018

• #3

You can't get an output voltage that is higher than the supply voltage.

Les.

 

ElectronicTy

New Member

• Mar 8, 2018

• #4

Thanks both,
sorry i'm a beginner and supposed to be writing a report on the results! makes a lot more sense when someone points it out ha ha.
do you know if 30v is the max supply for a LM741
Thanks again

 

JimB

Super Moderator

Most Helpful Member

• Mar 8, 2018

• #5

ElectronicTy said:

do you know if 30v is the max supply for a LM741

Click to expand...

Have a look at the datasheet.

I have also corrected the part number in the tread title.

JimB

 

crutschow

Well-Known Member

Most Helpful Member

• Mar 8, 2018

• #6

If you want to continue with learning electronics, one of the first things you should do is learn to read datasheets.
It will save you a lot of grief and misunderstanding in using a part.

 

audioguru

Well-Known Member

Most Helpful Member

• Mar 8, 2018

• #7

The 741 opamp was designed 50 years ago (!) and modern opamps are much better.
Its datasheet shows that with your plus and minus 15v supply some 741 opamps cannot produce more than 12V into a 10k ohms load.