Hi - starting to tech out a new project where I will need to have individual control of a large array of electromagnets through Arduino/Wiring- turn on, off & switch polarity. I will only need to pulse each one for a short period of time. The electromagnets will be <= 12v and low amps.
Wondering what kind of circuit I need here. I've worked with row/col scanning before and I was thinking that might work but the reversing polarity might be an issue.
Any tips?
--Roy
I'm thinking you could use H-Bridges.
The circuits they use to control motors.
Thats solves the reverse polarity problem.
The problem of a 'large array' is tougher. 
thanks - my first thought was an H-bridge too - but I need to control a bunch of e-magnets so I will run out of pins.
You could use 595's or similar to expand the number of outputs you have.
hey
what are the exact load specs-i.e how much current do the magnets draw? The 595's are a good idea, then you just need a bunch of driver stages to source the current for each magnet.
D
I've used hef4794's to expand i/o, the 595 will do that as well, their outputs would need to drive either one of the darlington output IC's or a bunch of transistors.
Just one of many.