In this tutorial, I'm going to introduce an extremely useful feature in LT Spice -- how to create a custom, parameterized part. I don't actually know what to call the resulting 'object' Maybe a block, a model, custom subcircuit, custom part -- I'm not sure.
The point is, you're going to have a custom circuit that you can create a simple symbol for, and then import and use with other circuits. Furthermore, instances of your custom model can have per-instance parameters!
For our example, we're going to create a simple model for a low pass circuit. We'll be able to import this block into other circuits, but each can have its own 3 dB roll-off frequency.
To start, we have to draw the model...
Drawing the model circuit.