so yea, 2nd year ee class, quick unit on opamps. not to bad so far.

However the textbook dumps the equivalent circuit diagram (first attached image) for an op amp on me, and...it makes no sense, because what the heck Is that set of triangular branches doing. proff's pulled out a similar diagram. For abit I've just been assuming i'm missing something and figure i'll get around to working it out

today we get a set of example problems, a diagram from one of which in is the 2nd attached image. In it there's a circuit with an op amp and the equivalent circuit. What's going on there makes perfect sense. It also has very little relation to the equivalent circuit in the first image.

I'm assuming that triangular set of branches in the first image, aren't actually branches at all, that they've used that triangle to block out what's inside and outside the device, and for some reason they've decided to make the lines the same colour and width as the lines denoting the actual branches? Am I in the ballpark here?

 

That triangle is just the outline of the part so that you can easily identify the input/output ports and what constitutes the equivalent circuit of the inside of the opamp.

Look at the left schematic of the second page. See that triangle? Look familiar?

 

It also has very little relation to the equivalent circuit in the first image.

The equivalent circuit in the first image is what's inside the op amp triangle in the second image.

 

this is what I was thinking. however till today we'd only been given the first equivalent circuit with little detail on the behaviour of the equivalent circuit. thus far through the course, that sort of line has been used purely to denote a connection between two components etc. Which means absent context, that equivalent circuit looks like all the port are connected in a loop for some bizarre reason I simply wasn't grasping.

It makes far more sense if that's the outline of the part and the diagram scheme for it is just bit unfortunate. thanks

 

http://www.ecircuitcenter.com/Circuits/opmodel1/opmodel1.htm

This will supplement your textbook on OPAMPs