Well not really but you guys seem to have a vast knowledge of motor controllers so thought I would throw this out..

I have a couple of old Cushman electric carts, one is a golf cart I use to haul my airplanes from the shop to my flying circle (see it really is about airplanes) the other is a newly acquired utility cart. Both have resistor speed controls, basically consisting of a foot operated rotary switch that switches in/out resistors depending on how far the peddle is pressed.

I have a pretty good background in electronics but not in high current motor controllers. Replacement solid state controllers for golf carts are pretty expensive and was wondering about the feesability of building a couple for my carts.

First question is what device is used to actually regulate the current to the motor. A string of high current pass transistors (think power supply) might work but the resulting heat sink and transistors would be pretty large.. Anyone have any idea of how this is done?

I'm curious...

In dollars, just how expensive is the golf cart controller?

Is that the prime failure mode of the vehicle?   

I notice that courses around  here are upgrading their fleets.  Maybe you could salvage one off an old cart easier than engineering your own.