This collection of schematic circuits are used as examples by me when teaching my students. They are all ready for easy simulation, with all necessary SPICE-models included. Some circuits are using built-in generic models. There is a PDF of the schematic for each of the circuits, in case you only want the schematic circuit.
To do a simulation, you access the "Simulate circuit in SPICE" button in the Schematic Editor. Then access "Run/Stop Simulation" button in the "Spice Simulator" window. To show other signals that is set up, you must access the "Add Signals" or "Probe" button. Commands for the simulator are placed just above the title field in the schematic.
The schematics are made with KiCad.