If you intend to use your stimulator with a partner it is important to know their stimulation intensity limits so as to keep play friendly, assuming that’s your intention!  You can only do this effectively if the intensity range, from 0% to 100%, is stable across the entire battery level range otherwise the intensity level value will not always represent the same output intensity.  Even if you are playing solo you do not want to have to keep increasing the intensity as the battery is dying.

This basically means if your intensity level setting says you are on 50% then you should of course be at around half way to maximum.  For instance, some stimulators might say that you are at 50% whereas in fact you are more like at 90%.  This means that for the remaining 50% of adjustment you will feel only 10% difference in intensity.

When using a dual output (2 channel) stimulator with both outputs being used it is important that there is no cross-channel interference.  For instance, if a butt-plug accidently came out during play you would not want to get a large current surge to your cock rings – ouch!  If the outputs are actively driven at exactly the same point in-time, then this is exactly what happens as a portion of current is effectively diverted from one channel to the other.  Similarly, if you increase the power to the butt plug, the power in the cock ring will simultaneously decrease, meaning that you constantly have to compensate.  Preventing this is achieved by ensuring that the output pulses are never actually active at the same time, but to the user it will feel like they are due to the relatively high frequency.

In order that nerves can recover or re-polarize it is important that the simulation waveform returns to zero volts between pulses.  At higher stimulation frequencies, typically above 500Hz, the transformers used to generate the stimulation pulses do not have time to recover and hence a DC (direct current) potential is created.  This should not be allowed to happen in medical TENS devices as this would be referred to as a patient leakage current which has an upper limit of 10 micro-amps.  However, most bespoke stimulators on the market do not care about the medical safety requirements as they are not registered medical devices.

Some stimulators on the market use exposed metal type connectors, a typical example being audio style jack plugs.  Although unlikely, it is possible for this exposed pin to be inserted into a mains power socket whilst connected to attached or inserted electrodes.  For extra safety, fully shrouded plugs are advisable for stimulator connection.  Again, TENS machines should comply as this is a medical safety requirement.

To ensure you get maximum life from your output cables (the cables that connect your stimulator to your chosen accessory/electrode) ensure that your stimulator is supplied with hi-flex cables.  These are often called Tinsel Wire Cables due to their construction which incorporates a fabric cord for tensile strength and has copper threads running through it.

For reasons of comfort it is important that you have full control over the stimulation intensity level just in case you go a little too high before you are ready.  This can typically happen on stimulators with dials (potentiometers or digital encoders) as these can easily get accidentally knocked.  It is therefore important that your intensity controls are responsive when turned quickly.

All ElectraStim stimulators will also start at zero intensity, no matter where you left off. This gives you full control over the intensity of the sensations. Lower quality units with dials in particularly can be accidentally knocked to the highest levels before they're turned on. It can be quite an unpleasant surprise to go from 0-100% immediately! 

Most modern e-stim devices are controlled by microprocessors which enables many features such as built-in patterns, audio processing etc.  However, to function correctly it is mandatory that battery monitoring and a controlled shut-down procedure is implemented to so as to avoid sporadic behavior at the end of the batteries useful life.  Some stimulators on the market have their power controlled by mechanical switches and therefore do not have the ability to shut themselves down when the battery and hence microprocessor supply start to “drop-out”.  This can give rise to what is known as a brown-out condition which basically means the memory and processor synchronization can be lost and peripheral features will start to fail.