I bought a Vitatronic TENS device with the following technical data.
Output voltage: Idling 0 to 80 V.
With terminating resistor 500 ohms
Pulse amplitude: measured at terminating resistor 500 ohms; 0 to 90 mA
(maximum output)
Frequency: 1-250 Hz
With this device I manage to trigger an orgasm.
I attach one electrode under the foreskin where my frenulum was (or I insert a metal rod into the urethra), and push the other electrode into the anus, isolated to the front. With this arrangement, I can optimally stimulate the prostate.
The electrode for the prostate, I made myself from a Caipirinja ice core metal 20 cm long self-made. For this purpose, I have insulated the upper thin end with insulating tape so that only the thick front side is uninsulated. This end is then inserted into the anus to the prostate.
The Caipirinja metal ice core can be obtained in the kitchen accessory trade e.g. Hoarding for the price of about 12 euros.
By the way, the polarity can be chosen by feeling. Personally, I have achieved good results, in which I reversed during a season + - (the polarity).
Just try it out.
Incidentally, the sperm anyway runs out with me almost without orgasm, but that seems to be normal with 73years and 27595 masturbation.