that makes things much easier
that one is using 35 IRF640 mosfets
http://www.ortodoxism.ro/datasheets/...cs/mXtvwts.pdf
for the datasheet for that type of mosfet.
18 Amps continuous 72 Amp pulsed. So without a cooling fan on the heatsink I would assume they would stay under the 11A continuous current. That gives 385A for the current with a capability of handling 200V input.
Seems pretty simple to build in theory, but getting the wires all together and attached to a large enough heatsink could be a real pain
As far as the pwm control in that schematic I think the guy who made it loves op amps. I would probably try and make it a bit simpler for hobby type stuff. Maybe use a 555 timer would be simplest but using a microcontroller would make the circuit way easier to build but would add having to build/buy a microcontroller programmer ~$25 to buy a basic one. Buck or 2 to build one. The only other thing I see in that circuit is a thermal sensor to monitor the mosfet temperature. Easy enough with a microcontroller and could even add a cooling fan in there. Also it could activate a contactor switch when it is at full power to get rid of the mosfet resistance when full power is needed. I still think a manual disconnect switch would be required for any type of controller in case of emergency though.
I could probably modify my nitrous controller and use it for the pwm driver that way it could be done with a 4x20 lcd and buttons to program the controller. If I ever get enough time free to dig out that old setup and figure it out I might try and build something.