>
> It's my aim to determine and eliminate every variable I can think of
so I
> can get back into electrification. One of those variables is polarity
> reversal timing, trying to maintain some comfort while still trying
to use
> DC at as slow a rate as possible, not into the hertz ranges.
>

My recent observations show a factor of x 6 the inrush
current during polarity switching using 24 square inch pads
on belly / back.

You seem to have vastly increased skin sensitivity which
shows as excess sensitivity after treatment.

Your 'equivalent circuit' [lumped component values resulting
in identical load to the power source] is a resistor in
parallel w a capacitor. My values [at wrist] are 4.7 K &
0.14 microfarads. Since you have a tolerance problem - best
guess is you have thinner skin & your equivalent resistance
is closer to 1.5 K ohms as indicated by the lower currents.

This makes you subject to 2 complications.

1. Replace your 36 Vdc pad supply with about 6 Vdc at the
pads. Result will be lots less ability to puncture your
skin insulation at switch time.

2. I expect you will need a 'low pass filter' between the
pad supply & your pads. It will need a much longer time
constant than bG has indicated to prevent high transient
currents.

3. My skin capacitance varies a lot w electrode location;
assume yours does too. Consequence is - takes longer [by x
10] for the current transient to die out by completing the
tissue charge change. There is a substantial fat layer in
the belly area so assume that's the primary difference.

4. Selection of a large nonpolarized capacitor will be a
problem. Electrolytics won't work [nor tantulums] due to low
reverse voltage & excess current leakage. Disc ceramics or
polypropylene or mylar can be used but needs a lot of them
in parallel to get the capacitance total high enough; will
likely have to live with that or find a speaker crossover
nonpolarized part that doesn't leak much. At 6 Vdc, this
becomes easier. You need enough to get about 4 seconds
for the t = RC time constant.

O_______________/\/\/\____O_______
R | |
6 V cap, C | you
| |
O_________________________O_______|


If your parallel R = 2 K, your pad area = 1 sq inch [each] &
you want 0.1 mA, then your pad voltage becomes V = I R = .1 x 2
= .2 volts so the remaining drop has to be due to the
series R = 5.8/0.1 mA = 58 K ohms which includes whatever
leakage current the new cap = C does.

Then C = t/R = 4 sec/58K = 69 microfarads [at 6 Vdc];

might wind up w a batch the size of both fists.


This WILL look like overkill. You may find you don't have
to add that much but gives some idea what you're up
against. It also allows lots longer time between switches &
should get you pain free results. The lower currents will
need proportionately longer treatment times. Any change in
pad area will need a corresponding change in the R & C.

5. If you do manual switching - get a double pole double
throw center off switch. This allows you to do 1/2 the
charge change at a time & further eases switch transients.


Good luck. Joe.