Hi all, i have faced a problem in the designing stage of a machine. I need to use a mechanism to close a door (very small metallic door of about 20 grams) for a period of time(this period can go up to 10 or more minutes) and then go back to its previous position in which another door is closed. I mean that the door is in position 1, closing a path all the time, and then for some time maybe once a week for a certain application it should go to position 2 and close another path for about 10 minutes or more. the door is square shaped metal which is rotated around one if its edges to go to position 1 or 2. two things are very important. 1. The door should go to an exact position that it should be in order to effectively close the doors.(i am using a stopper at each end to make sure that the door doesnt go further.) 2. when the door is in a position, some objects are passing the path and they hit the door. i dont want these objects to move the door and the other path(which is currently closed by the door) becomes open. what kind of motor or actuator do you suggest? if a dc motor, how can i make sure that it remains in its position all the time because i know that the electricity should not be maintained on the motor because it will overheat and short circuit. thank you all, sorry for the long question.