Thanks! I'll check it out. I've also just downloaded KiCAD - seems a bit more polished than TinyCAD at first glance.

But pretty much all of them seem to be oriented around PCBs and integrated circuits. All that ('electronics') is a mystery to me, but I'm OK with basic electrical circuits.

What I mainly want to draw easily is a machine circuit diagram - with AC lines, contactors, start/stop pushbuttons, inverters, motors, inverter control wiring, that sort of thing.

I'm sure it's do-able in any of these systems, but neither of the two I've tried so far seem to have suitable component symbols built in. I probably just need to work out how to add in a suitable library...