This circuit has been designed for use with 200VDC motors, such as those found in treadmills.
It uses a cheap triac motor controller, which can be found on eBay listed as 2000W SCR Motor Controller.
With an input of 240V AC, the maximum rectified output of the SCR controller will be 340V DC peak. The circuit was modified for use with 200V DC treadmill motors. This simply required replacing one resistor on the PCB (see schematic).
The circuit fits in a small metal enclosure.
