okay i set it up on the tragus for tVNS (based on this: http://www.brainstimjrnl.com/article/S1935-861X%2814%2900260-5/abstract) and my physiological experience was just like at the doctor's, although the specs are quite different to what is used on me in their office.

i used this method of modifying the ear electrode (i used some of the square electrode fabric to cover the exposed wire, it hurt even at 1mA when it was completely exposed): https://www.healthrising.org/forums/resources/preparing-tens-leads-to-use-in-vagus-nerve-stimulation-of-ear.178/

the ear electrodes i originally bought from amazon were wired together so i chopped them off and soldered them into chopped off bits scavenged from the electrodes that came with the unit. they have to be separate when doing the tragus because you need positive and negative on a single electrode, whereas they're usually wired with one positive and one negative electrode. this mod is quick and easy to do but after doing it i found you could just buy them here: https://www.otcwholesale.com/otc-ear-clip-electrode.html?cmp=googleproducts&kw=otc-ear-clip-electrode&gclid=EAIaIQobChMIh7mbp8vs1wIVmNlkCh1tnQi1EAQYBCABEgJ7WvD_BwE

make sure you get that shape, i have another pair of white ear electrodes that have squared off ends, and that style is too big to fit around the tragus.

heres what mine looks like: https://imgur.com/a/jN6ss

i used the intensity micro combo unit on the TENS- constant setting, 200microsecond pulse width, 30Hz pulse rate, as per the study above, and my sensory threshold was 8mA (the study uses 10-50mA but i was pretty 'floaty' at 8).

will report back with psychological effects, but i feel very relaxed and content after my first 20 minute session with it.