# sch-rnd - use cases

## The "transistor" problem

### Setup

- sch -> pcb flow
- generic (light) symbol in the schematics (e.g. a generic NPN)
- footprint attribute set to a generic footprint (e.g. a generic sot23)

### Problems

- the pin numbering of the symbol is arbitrary
- the pin numbering of the footprint is arbitrary
- a footprint+NPN doesn't determine the pinout: there are various NPN devices with different pinouts with the same footprint
- number of logical pins may not match number of physical pins; unused pins, mutliple pins connected