Looking for some help here with my WiFi Chicken Door. I have a 12V 3A Linear Actuator and a 12V DC power suppy as well as a Wifi Controller. What I am looking for is guidance on the correct polarity reversing relay. It appears I need a DPDT relay but not sure which one to get and how to wire it to reverse polarity when power is supplied via the wifi switch. What should the Amp rating be and how should it be wired? Any help is greatly appreciated.