I'm needing to replace solenoid contactors with something silicon for control of a 12V / 25A DC motor. Speed control is not an issue; I only need for it to turn clockwise or counter-clockwise. Currently this motor is being controlled with four solenoids which reverse the polarity to the motor to change directions. I'm hoping to replace this with a completely solid-state solution, including wireless activation.

I've come across various devices that might do this kind of thing -- MOS-Controlled Thyristor being one of them, but I'm having trouble finding solid data on actual devices. Is this technology obsolete? If so, what's the new solution?

 

One of the more popular silicon devices for DC control at present is the IGBT (insulated gate bipolar transistor). Try going to digikey.com and typing in igbt in the search box. Next select semiconductor devices. A parametric search engine will allow you to check devices from a few amps to 600A. Controlling these to give forward and reverse (CW and CCW) rotation will require little more than low power devices as the insulated gate requires little current load. The major problem of these devices is that the typical voltage drop collector to emitter is greater than standard bipolar transistors. You can also consider using bipolar transistors in a darlington configuration (2 transistors seriesed to increase gain) available in a single package if the IGBT drop is too much for a 12V application especially since bi-directional control requires control devices on both sides of the motor leads.