He didn't invent the wah at all, it was already being made by Vox at least before him. He invented the univibe, and the octavia too, well Roger Meyers did for him. I don't know who invented the wah pedal, but they were originally used as foot operated tone controls, before peoplle came to realise the effects that could be created by rapidly swinging it back and forth. I will do more research to find out though.