I have a precision burden box, whose burdens are switched by a rotary switch, and there are 21 positions. I want to make it "digital controllable", that is, using MCU to switch between these burdens. The current flow through the burden may be 10A max. Now I list the possible methods I know. In all method, I need to consider the current capacity and on resistance, and for some methods, I need take more into consideration.
- Using solid state relays. (The on resistance and current capacity maybe a problem.)
- Using MOSFETs. (I need work more on the driving circuit and heat-sink design, as well as the space maybe a problem.)
- Using electro-mechanical relays. (The on resistance maybe a problem. Is there a relay with Ron comparable with a rotary switch, that is, <10 mOhms? )
- Using a stepper motor to drive the rotary switch. (If using open-loop, I can't know exactly the position of the 'wiper', so it may not be reliable.)
That's what I know for now. Can someone give me some suggestions on the possible methods, or some recommendations on parts selection.