System common to solenoids is NEGATIVE
Boards use UDN2981a IC's rated at 40v DC
500 mA per gate, 8 gates per IC.
If more than 3 gates are on at one time the current output has to be lower.
Boards are available from 8 notes to 64 notes. The 64 note boards can be extended with modular boards up to 128 notes.
Programmable to any note on any channel.