I know we all do some testing on our benches and not everybody has all the professional testing equipment. Either we're not on our well equipped bench or you need something on the fly so we at times have to improvise. With so much at our fingertips in this very technological age that wasn't at our disposal 15 to 20 years ago, I'm curious to see what some of you fellas have as quick smartphone or tablet tools. Share yours if you will. I'll start with one I've used a few times to put a test tone into a mic.