We are frequently asked why we can’t simply run the Insight while charging directly from the USB port. The reason is that there is no way to know if the power source is intrinsically safe. Emotiv Insight basically consists of seven electrical contacts directly attached to the user’s head, powered from the internal battery inside the main pod. If we want to be able to run the headset safely while connected to mains powered equipment, we would have to build in a high degree of isolation into the Insight input circuits. This is not practical for two reasons. The first is that the added components add a significant expense and complexity to the headset. We decided it was not fair to force everyone to pay for a facility that only some users need – the increased price would also be a disincentive to new purchasers. The second reason is the weight and size of the isolation components and the necessary board and component clearances to avoid spark-overs. The size and weight of the Insight would have been greater, making it a lot less sleek and top heavy (most of the extra components are transformers which are not exactly tiny!
Because of these considerations we decided the best course of action was to disable Insight operation while connected to an unknown charge source, and move the expense and weight of the isolation systems to an external device which could clip on the pocket. It was a no-brainer (sorry, pun intended) to add the battery and other capabilities to the Insight Extender pack.