There have been a lot of questions lately about transistors, NPN vs PNP, Bipolar or BJT vs FET and their use in "H" bridges. I had considered doing a tip/walkthrough on the subject but typing "transistor" into google gave lots of great results. Same happened when I typed in "H bridge design". I realised I would be wasting my time writing a tip/walkthrough on either subject as there is better more detailed explainations already available. So for those who are afraid to google I present these links.