You can't do tDCS with a frame, only TMS. You're confusing the technologies! In trials they do shams by turning on the device for only a short period of time.

You can't do tDCS with a frame, only TMS. You're confusing the technologies! In trials they do shams by turning on the device for only a short period of time. That way there's still a tingle (from the pads) at the start of procedure.