>- Also the device made by Bock Beck uses 4Hz i think and a alternative current and in his videos he explains that it manages to damage/kill bacterias, viruses
Well, it is approximately 4 Hz due to the components used but it is not alternating current but is actually an inverting polarity output in which one electrode is positive and then the other electrode becomes positive during the second half of the cycle. In this way, one output electrode is always positive even though observing the signal on the scope can be deceptive.
The BBBE normally has a roughly 50 percent duty cycle, the same as most zappers.