I have a limo business with an older limo that is experiencing electronic control problems. I could pay 1700 for a new control system, but the limo can only be registered in this city for another 2 years so I just don't see it being worth the investment. I am talented enough to completely create my own relay and switch based control system but I can't figure out the fan motors. The limo has five fans that the limo all runs at the same speed (H/M/L). I figure I can control one at a time with potentiometers or various value resistors on a three-position switch to achieve the same control but for only one motor. Is there a device that will allow me to say feed a variable reference signal, and have that device output the same voltage but be able to take the amperage of these motors. Each motor can pull up to about 15 amps. I figure for example feed a six-volt reference signal branched out to say five of this device (one dedicated to each motor for isolation purposes) and have that device duplicate that voltage from an input of 12-14 VDC.... Is this possible?