electromagnet controller
This would be a perfect job for H-Bridge and PWM (pulse-width-modulation) ..
See example at:
If you don't want to go that far then transformers+rectifiers should work well too ..
If you have two identical transformers you can connect their windings any way you like: in series or in parallel ..
To increase output current connect two secondary windings in parallel but I would use small power resistors, such as 0.1Ω/5W, or even less than that, per each output to balance currents drawn from both windings ..
Regards,
IanP
BTW .. Make sure windings are connected in the right phase .. note phasing dots on secondary connection points 5 & 7 .. see picture below