I have a Physiomed TPN200 TENS machine.
http://www.physiomedhomecare.com/TPN-200-Plus.html. This is a good quality machine available for about £20 - £25 new. It is a two channel device that comes with self adhesive pads that last for scores of uses and can be revitalized by a little water. The power source is a PP3 battery and I use a rechargeable one.
There are three types of output. Modulation, Constant & Burst modes
• Variable pulse rate 2Hz-150Hz
• Variable pulse width 30µs-260µs.
The only change I made was to take two wooden clothes pegs (clothes pins) and drill a small hole in each of the jaws to take a brass drawing pin (thumb tack). I soldered wires to the pins and prepared the other ends to push into the leads from the TENs unit.
The best way of using the TENs I found to be to fit the modified clothes pegs to the red terminals and sticky pad s to the black. The cloths pins I clip to my nipples and the pads – one under my penis and the other to its head. The modulation is the best setting at maximum pulse rate and width. This can be very erotic and if the sticky pad is cut down a bit and stuck to the eye of the penis it can feel like a dry orgasm.
The usual TENs safety rules say connections never made between nipples – i.e. red to one and black to the other.
However, the following article disagrees that it is a risk under normal circumstances.
TENS is an acronym for Transcutaneous Electrical Nerve Stimulation. (Transcutaneous means through the skin - from the Greek).4
It is a low voltage penetrative unit. The unit generally uses a nine-volt battery (or alternate equivalent source) as the power. Because if this, I have heard people state that the violet want (which may drive upwards of 15000 volts) is more dangerous. But, this is untrue.
As we discussed earlier, the high frequency and exceptionally low current of the violet wand are not capable of penetrating the skin. Therefore the resultant electrical discharge from the device is equivalent to a static electrical (albeit continuous) shock. The tens unit on the other hand, takes this 9VDC charge and using electronics amplifies the output into a “step AC” (a dc voltage given frequency) and using capacitors, the voltage is boosted as well. This gives it the ability (through the low frequency [2 to 120 Hz – pulses per second] and higher than 9VDC) to penetrate beyond this tertiary layer of skin (your primary protection against electrical shock).
Now, please understand, a well functioning and properly utilized tens unit is safe. As mentioned, the voltage is boosted, a frequency is created, and it is capable of penetrating the skin into the nerves of the muscle; however, normally the voltage and frequency produced are less than potentially viable for passing through critical areas of the body (when used correctly). That is why we (who play with electricity) often hear about the inherent potential danger of placing the two electrodes in positions that would place the heart in between (such as across the chest’s pectoral muscles).
People do this (however) either for therapy or for fun. And, I can truly say that I have never seen any adverse effect in this (I do not, however, recommend it as you - my friend - may be the one I hear about).
http://www.bdsmdebunkingthemyths.com/electroplay.htm