>- All Clark Zappers are made with the 555 integrated circuit which all output positive
Very wrong. Some zappers use other chips.
ParaZapper does not use a 555 times for timing because it is too crude. ParaZapper uses sophisticated industrial microprocessors for signal generation.
It does use a special newer version of the 555 as a part of the output circuit which is much more sophisticated.
The Beck zapper is correctly an AC zapper and there are a number of published studies that show AC does not kill microbes.
>- then she came up with
She came up with positive offset because some sellers were building their zappers with capacitors in the output that could cause a negative spike. Not all Hulda Clark Zappers were having that problem.