Hi,
Can tell you in Bob Becks audio from the web, he specifically says not to use the TENS unit as a Brain Tuner, and gives the reason which I can post if required. But he says you can use the brain tuner as a TENS unit.
He also says for the blood purifier device that AC current should be used (equiv to alternating DC) to prevent electrolysis. IF you want the recording where he says this let me know.
Kind Regards
Leon