We are using an arduino to selectively apply 5V to the gate of MOSFETs, with the intention that current will only be allowed to pass through our solenoid from the supply in the situation where both the MOSFETs that a particular solenoid is attached to have a gate voltage of 5V. 5V appears to be above the threshold voltage for these MOSFETs (IRF520) but we are getting much less current than expected unless we increase the gate voltages. Can anyone explain this? Is it a problem with our circuit or the choice of parts? Is using two MOSFETs back to back like this a bad idea?
We will eventually be controlling a larger grid of electromagnets to selectively turn them on for several seconds at a time, up to 5 at a time. This grid will be up to 17x17 so it is not ideal to use a MOSFET for every magnet!