I have a train on a track that will run on 12 volts. The train will go down the track to the end and stop. Then it will change polarity and go the other way to the opposite end and stop and switch polarity again. This will be repeated until I stop it. The time it takes to go down the track will be under on minute. I was thinking to stop the train at the end of the track with a timer. Any help would be appreciated. Thanks,Ernie