Hi,
maybe one problem is the definition for "DC":
* is it 0Hz, a straight line (either positive or negative), no waveform at all?
* or any waveform that is purely negative or purely positive
For me personally:
I think about the first. A straight horizontal line. Thus, for me "pulsed DC" does not exist.
Thus when I hear about "pulsed DC" I think about: AC signals (frequencies) combined with a 0Hz (DC) signal.
When you differentiate between AC and DC .. what is your definition?
Best is if you give clear values/specifications:
Example:
* 1V AC ... is rather ambiguous. --> 1V RMS 50Hz sine wave is rather clear.
* 1V pulsed DC is rather ambiguous. --> 0V/1V square wave, 50Hz, 30% duty cycle is rather clear.
***
Then you talk about "dangerous".
Touch a 12V battery (pure DC, straight horizontal line) wiht your fingers .. you will barely feel anything.
Touch a 12V AC 50HZ square wave ... you may feel it.
None of both is considered dangerous, because the current will be too low.
While you may feel nothing when touching 12V with your fingers ... you will clearly feel 1.5V when touching with your tongue. Touching a 9V battery (for me) with the tongue is really unpleasant ... I don´t want to try 12V at all.
This means ... it matters "where on your body" you touch the signal. There are places that are mor conductive than others (resulting in higher current) and there are places which are more sensitive than others.
****
* The "danger" of an DC signal is that H2O (water) is decomposed into hydrogen and oxygen. And on higher currents the skin may get burnt at the contact area.
* The danger of low frequency AC is that when run across the heart it can mess up your heart rhythm. This may cause immediate stop of heartbeat ... and it may even may cause late heart rhythm problems even after many hours... depending on current amplitude, time of exposure, frequency, current path...
* The danger of high frequency AC is that it travels along the skin ... and my burn wide areas of the skin .. not only at the contact area.
* The danger of microwave frequency AC .. even non conductive .. may cause your H2O molecules to resonate ... = heat up ... like the goods in a microwave stove.
******
Now you asked about voltge and current:
Because of size of contact area and because of contact skin conductivity the overall resistance varies in a wide range. Thus the current varies in a wide range. Thus intruducing current ... overcomes the personal skin conductivity problem .... and results in more predictable reaction.
*****
All this is not new. It has been studied in detail. You may find a lot of good documents in the internet. Just do a search.
Klaus