I need help in designing a D.C. solenoid former. I am aware of eddy currents in an A.C. solenoid or transformer, & note that D.C. solenoids can have a metal former wich is in effect a shorted turn, (but as there is no alternating magnetic field there is no eddy currents) but I wish to pulse a solenoid at about 3 Hz. The solenoid current will be about 2 amps. I could slit the former & provide an air gap, but prefer not to. I have searched the net but can't find any info re shorted turns with pulsed D.C. Any constructive comments greatly appreciated. Davey.