I'm working on a project to wire up a pipe organ's windchest using an Arduino as the backing system.
I'm looking to wire up about 400 outputs worth of solenoids that draw about 100mA of current at 14V each. I have a power supply that can handle this.
What I'd like to do is to create a system with an Arduino and something like a MAX7221 to be able to drive a lot of outputs with only a single Arduino. Obviously with those current requirements I'll need to use MOSFETs or something similar if I'm going to know with a MAX7221.
Besides spinning my own board with a MAX7221s and a diode matrix of MOSFETs are there any other good solutions to help keep costs and complexity down?