DC motor control

[Mechd07]

I would like to use 0-18v DC @ about 1 amp to control 16v DC @ 125 amps or even 115 volts AC from separate power supply. When the control voltage changes polarity the output voltage to a motor should also.

What can I buy or build to accomplish this?

 

[itsmoked]

Ack! Don't double post, as all the engineers round here check all the EE forums.