in the context of what HC was trying to say, every single cycle of every single zapper ever made by anyone with any output voltage and any frequency "goes negative".
Not if you consider this as the pressure/movement of electrons: a "positive offset" (minimum voltage more than 0V) will ensure that the electrons always pressure/move from one polarity to another (in theory, because we don't know exactly how the electrons behave in the human body...)
First, we *do* know how electrons behave in the human body, and you just said it. They move from the more negative potential to the more positive one, through the maze of resistors, capacitors, and inductors that is the human body. That's what electrons do, and it pretty much is *all* they can do. So in the context of your sentence, it isn't theory, we do know, and we've known for at least 100 years. Note that we're talking about simple electron movement here, not biological effects.
But this has nothing to do with "positive current" or "negative current" which are concepts...
Second, positive and negative currents are physical reality, just like water in a garden hose. Electrons are physical particles that move under pressure. Yes, electrons are other things also, but electric current (electron flow) is way beyond concept, and this one is over 200 years old.
Now, if you are referring to "positive" and "negative" as concepts, then we are on exactly the same page (as I babbled on and on about a few weeks ago). That they are concepts rather than absolutes is foundation for where I'm going with this. Thanks for playing along.
... a "positive offset" (minimum voltage more than 0V) will ensure that the electrons always pressure/move from one polarity to another...
No, it won't, not ***always***, and that is where I'm heading.
A stereo analogy: With The Who playing on the stereo, there are three things you can do to eliminate the sound.
1. Turn the volume all the way down. The stereo still is on and the speakers still are connected, but they are playing music of zero volume. This is *not* the same as playing no music. Electrically, it is different from...
2. Disconnect the speakers. Now the source still is making watts and watts of audio, but it is physically disconnected from the load. There are zero volts of audio at the speakers, but for a different reason from #1. Or ...
3. Turn off the stereo. Now the speakers still are connected and the source is still playing, but the amplifier is not energised, and so is not amplifying or even passing through the signal. The speakers still are connected, and still see the amplifier output stage, but its electrical characteristics are very different from both #1 and #2.
In all three cases a scope would show 0 volts at the speakers, yet how the speakers are interacting with the source varies greatly among the three cases. The point is that when you look at a signal on an oscilloscope and see that it is at zero volts, there are at least three *very* different reasons for the signal to look that way, and the interaction between the electronics and the external load are very different for all three.
So, when the zapper signal at the handholds goes from 8 or 9 volts down to zero or very near zero, there are at least three different things that can cause this. Unless something is broken we all know what is going on. But Clark's writings clearly indicate that she not only has no awareness of this, and knows nothing about how the three cases affect electron flow in the human body, but also that she is explaining her device using the *wrong* case. This is why her obsession with offset was uninformed, why her circuit update to "improve" offset was the perfect way to show how little she understood, and why none of it mattered anyway.