An external microphone power unit for your video camera vk3ye Published on Sep 23, 2016 Good wireless microphones for video cameras may be too expensive for the casual YouTuber. Provided you can live with the cable a lapel microphone is a good substitute, giving results better than either the camera's internal microphone or a cheap wireless microphone. However electret elements require a power source. If your camera doesn't supply power up its microphone cable you can build a box that does. This video explains how.