Just a quick one for you all.
Last night while building my digital interface (see immediately previous post) I wanted to test the wiring up of the audio cables and the isolation transformers. For this I obviously needed a nice steady signal on the input and then I could use my digital multi meter to measure the AC voltage on the secondary of the transformer. So, being audio cables with 3.5mm connectors, I simply plugged them into my iPhone and ran Tone Generator Pro.
Using this it was easy to switch on and see the voltage rise across the secondary, and then conversely switch it off and see the voltage disappear. Further, I could increase the volume on the phone and watch the voltage increase – and again, conversely decrease.
All in all, it's allowed me to have confidence that this part of the AC circuitry is working with nothing more than my mobile phone and a DMM. Noice.