Drawing in-place op amp in LTSpice

Thread Starter

Doug Edmunds

Joined May 29, 2019
5
I am modeling a schematic of a voltage follower/buffer from a book
into LTSpice (I used a 5V Vin source and +/- 10 V for the op amp sources).
Here's what I drew, which does provide the correct Vo.
I am not taking classes any where, so it's not really homework.

My question is whether there is a better way to draw the connections.

follower-diagram.png follower.png
 

eetech00

Joined Jun 8, 2013
1,736
I am modeling a schematic of a voltage follower/buffer from a book
into LTSpice (I used a 5V Vin source and +/- 10 V for the op amp sources).
Here's what I drew, which does provide the correct Vo.
I am not taking classes any where, so it's not really homework.

My question is whether there is a better way to draw the connections.

View attachment 187352 View attachment 187351
Hi

The schematic in post #3 is correct for a circuit that uses a bi-polar supply.

However, your schematic does not show use of a bipolar supply. The lower supply terminal is connected to ground implying a single supply.

The input signal source connected to the + input terminal is referenced to ground as well as the output. So the output voltage would range between ground and the positive supply voltage.

One thing to keep in mind is that it’s important to show all signal and supply sources on the schematic so as to enable correct analysis. Otherwise, assumptions would be made that could be incorrect.

eT

upload_2019-10-5_15-30-9.png
 
Last edited:

Thread Starter

Doug Edmunds

Joined May 29, 2019
5
The schematic is from a 1987 book by Leon Choa. I am pretty sure that is just a ground wire for the op amp source, like in this other image from the book.

follower-diagramb.png


Hi

The schematic in post #3 is correct for a circuit that uses a bi-polar supply.

However, your schematic does not show use of a bipolar supply. The lower supply terminal is connected to ground implying a single supply.

The input signal source connected to the + input terminal is referenced to ground as well as the output. So the output voltage would range between ground and the positive supply voltage.

One thing to keep in mind is that it’s important to show all signal and supply sources on the schematic so as to enable correct analysis. Otherwise, assumptions would be made that could be incorrect.

eT

View attachment 187365
 

eetech00

Joined Jun 8, 2013
1,736
The schematic is from a 1987 book by Leon Choa. I am pretty sure that is just a ground wire for the op amp source, like in this other image from the book.

View attachment 187368
Hi

Case and point.;):)
That illustrates exactly what I mean by showing all signal sources and voltages on the schematic so there is no misunderstanding when discussing them.

Post #5 is correct for the schematic shown in post #1.
Post #3 is correct for the schematic shown in post #6.

Thanks for that clarification.

eT
 
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