Op Amp schematic

The central piece of any op-amp is called a long-tailed pair. I'm not clearly seeing one here, but they do vary a bit. The simplest long-tailed pair has 2 resistors, 2 transistors, and a constant-current sink or third resistor connected to the emitters/sources of both transistors. Here's one configured as a very crude op-amp: https://everycircuit.com/circuit/5442599488585728 If you look at the op-amp in EC's library, you'll see FETs used for the 2 resistors and a current mirror for constant current. Some op-amps have transistors in various configurations in place of the 2 resistors. Some BJT op-amps can even omit a resistor because BJTs control current. My "op-amp e2g" shows how simple an op-amp can be in simulation: https://everycircuit.com/circuit/4998086501072896 It couldn't be made quite right in real life; it would need a few more components & lots of hand-adjustment. This one is uncommented, but crake usually knows what he's doing: https://everycircuit.com/circuit/5030928467099648 Finally, good power amps are usually op-amps. Here's a fairly simple one from Rod Elliott: https://sound-au.com/project3a.htm You can see the long-tailed pair clearly near the left side of the circuit diagram. The bit below it with the LED for a voltage reference is the current sink. I highly recommend Rod's site; I learned a lot from it. https://sound-au.com/