I'm trying to build a circuit to let a Raspberry Pi control 12 linear solenoids. The solenoids are rated for 12 V and 400 mA, so they should have a resistance of 30 ohms. However, on the force-stroke curve the manufacturer lists, there is a 25% duty cycle which draws 15.2 W. Does this mean that the solenoid is powered with around 40 V instead?
This brings me to the issue of powering these solenoids. Their application (pushing piano keys) will probably require a 25% duty cycle. If I were to use a 24V power supply, I would be supplying (according to P = V^2/R) about 19.2 W of power to each solenoid. The voltage/power specifications come from the heating/duty cycle, so I assume this should be fine as long as my duty cycle is kept in check. This would require 19.2 W * 12 = 240 W of power for 12 solenoids. Assuming I would be pushing a maximum of 6 keys at once, would a power supply like this be sufficient? It's a 150W power supply, so (240 W) * (6 / 12 keys) with a 20% safety factor. Since the solenoids are inductors, I don't really know how to estimate their power usage (or how much of a safety factor I would need).
I'm really sorry if this is a bad question, but I don't want to order the wrong thing. I've already tested the circuit with one solenoid and eight AAA batteries (so 12 V) using a Raspberry Pi connected to these MOSFETs. Any help would be greatly appreciated!