I got a small motor, like one out of a remote control car. It runs off of a 6 volt battery. When you turn the switch on, it comes on and stays on (like it is suppose to do). But, I want to put a relay or timer in it that would make it run for 15 seconds and then shut off for 5 seconds. Then when the 5 seconds is up, it will come back on for another 15 seconds. How can I accomplish this and would it be expensive???