The Zapper is not to be confused with the TENS unit that relieves pain in body area. Zappers are for health therapy,- but only if made the right way. Yes it puts out what's called square waves that can be seen on any oscilloscope and the $35 China Ebay battery/power supply scope also- DSO-138 welded. The cells of tissues communicate with tiny square waves and is reason why this unit works. The output frequency wave to ground is to be about 1/4 volt positive offset level above ground line on scope verified. (Accomplished with extra resistor) Output across hands is about 5.5 Volts pulsing on + off DC only at low uamp current levels. (Not AC or DC) My unit hand made has 3 meters , so as I know it is working and not just an "on" led. Units on Internet can be purchased for $10 up to $800. Many companies make these. Get the $60-70 dollar one with switch for 2 frequencies and verify it has 2 copper separate handles- not wrist straps. The pulses go over the WET hands skin surface and travel down acupuncture points under the skin through meridians to various parts of body. (Except digestive system) This was to remove pathogens and revitalize body cells for rejuvenation. (That woman in Indiana Jones movie later eliminated her mosquito virus disease using her Zapper after thousands of dollars went to doctors. Her story is on Youtube.) Dr Hulda Clark's MAIN book is called - The Cure For All Diseases and is in many languages, and contains medical data and schematic of simplified Zappers. There is series of her other books and test manual for the "Syncrometer" contamination tester which is variation of electrical resonance frequencies of the skin biofeedback tester. People can treat themselves at home and not have to travel to the Mexico clinic. Her lower Ca. store sells equipment and the books, and the Cancer treatment herbs.