[sdiy] midi to mosfet - question

[Christian.Bergmiller at daimlerchrysler.com]

Hi,

i'm currently building a midi to mosfet "open drain" 32 channel interface.
It uses the AT90S2313  uC, 4* 4094 shift registers for I/O extension and
32* 2SK1904 mosfets on the outputs.
On breadboad it worked ok so i am prototyping it on some kind of
stripboard.

I want to put the whole thing in a box and connect it to the world via 36
pin centronic connector.
My question is if swirtching 32* 24V Solenoids at 500ma connected via
3meters of Cable (just an example)
will produce hf noise (or whatever :-) that would couple into equipment
used around it ??
is shielded Cabel enough protection. do i have to use some kind of "slew
rate limiting" ?
Or should i put this interface just as close as possible to the solenoids
has to power ?

Thanks
Christian