I'm trying to build as simple a circuit as possible that will pull a logic line low every time an automotive ignition coil 'fires'. My first inclination is to simply attach the 'negative' terminal of the coil to the base of of an NPN BJT through a current-limiting resistor, with the emitter tied directly to ground. So there would be 5V on the collector and roughly 300V on the base resistor when being triggered. Somehow, though, I feel like I'm missing something fundamental that won't let this work. Perhaps it's just me being spooked by the 'high' voltage. I suppose I could use a voltage divider at the base, but I still feel like I'm missing something. Looking for confirmation regarding the proposed functionality, or of my idiocy. Thanks.
Edit: I don't intend to pass any current through the transistor, besides what little is required by the device itself. The idea is that the transistor will go into saturation when the ground is removed from the coil (when the counter-EMF brings the coil's 'negative' terminal up to around 300 volts). Here's a (rather amateurish) schematic of what I'm thinking:
Switch 'S1' in that schematic is just a placeholder for the IGBT/Points triggering the ignition coil. Sorry again for the confusion, and thank you, everyone, for all the replies!