Dear Mr Wayneh Ji
Greetings.
I hope that I have done some thing finally and trying to disturb you to correct it as a meaningful thing for the real world application.
Assumptions
1. Random period and polarization are not necessary.
2. Body resistance: 10 K ohm to 150 k ohm (no conducting gel, only conducing pad or electrode)
3. Schematic with 555 (timer) and JFET (12SK170X) as attached.
4. Power supply for 555 IC 9 V and for JFET 15 V (not specific).
5. R3 load resistance varied 1 K Ohm to 200 K Ohm
Simulation
At 10 K load V=1.8 V and I= 180 uA
At 200 K load V=11 V and I= 55 uA
Even at 1 K Ohm load V=0.85 V and I= 850 uA
If this circuit works (your confirmation needed), then the values are at the safe level irrespective of low voltage at low load resistance say below 50 K Ohm (V=6 V and I = 120 uA).
Problems faced: Proper biasing of 12SK170X , when tried to increase the voltage below 50 K Ohm load, hence tried to keep R2 as low as possible in order to pull down the gate voltage.
Finally, through this update I tried to confuse you as little as possible please

 

Dear Mr wayneh Ji,
Greetings
Now I made the JFET as a self feedback one as shown in the attached schematic.
Now the out put voltage is stable irrespective of loads from 1 K ohm to 200 K Ohm, but current varies.
The out put voltage depends on input voltage only. For example if input is 5 V, output around 4 V irrespective of load resistance. If in put is 9 V, output around 8 V and if input is 12 V output is around 11 V.
Now I need your correction and confirmation for the followings please :
1. Will this circuit work
and
2. How to stabilize current (constant current. Like that of voltage) for various loads.

 

Dear Mr Wayneh Ji
Namaskar
Greetings
My learning process took that much long time, hence this delay in reaching you for further learning process please.
I made a simple biphasic microcurrent circuit using LM358 IC and NE555 IC. The idea behind this circuit is to have an out put voltage of the order of 27V, by replacing NE555 (test circuit) with commercially available 2 channel PWM board with a supply voltage of 27.
The circuit works fine in LTspice, exhibiting a biphasic wave but not in assembled one (tested with DSO 138 pocket size oscilloscope. The exhibited wave is polarized not biphasic as exhibited in LTspice.
Due to my limited knowledge I am unable to understand such a type of exhibition, hence trying to reach you for corrections please.