Again from Sebastian Anthony
Even at $99, the GoFlow kit is fairly expensive. Just so you understand just how simple tDCS is, all you have to do is pass 9V at 2mA through your scalp for 30 minutes. To do this, you need a battery, some electrodes, a resistor, and if you’re feeling snazzy (and safe) a current regulator. To be fair, for your $99, GoFlow will give you a plastic housing and provide a potentiometer — presumably so you can find the right voltage for your brain. You also need to know where to place the electrodes on your scalp, to boost the right area of your brain. Judging by the picture on the right, GoFlow will provide a map of the various regions.