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  • #608132
    BOB BLACKSHAW 1
    Participant
      @bobblackshaw1

      Hello all, I have been using a Tens Machine for many years and still use one which must be 25 years old, the up to date models are better and have more options. The reason for this question is that the original Tens had a fault, I remember I was in a hotel I switched the Tens on the

      four pads were placed on my lower back, as I switched it on I was knocked to my knees to the floor, and was left with four red type shock burns on my back, it automatically switched on at 10 the maximum. The power from these machines is amazing using three AAA batteries and the batteries last a very long time,the original Tens can be left on all night the new ones switch off after half an hour, this only happened once so that's why I still use it. My question is how can three AAA batteries have that power and last a long time in use. I've used the search on the forum with no results.

      Bob

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      #28789
      BOB BLACKSHAW 1
      Participant
        @bobblackshaw1
        #608135
        roy entwistle
        Participant
          @royentwistle24699

          What is a Tens Machine ?

          #608136
          Russell Eberhardt
          Participant
            @russelleberhardt48058
            Posted by roy entwistle on 02/08/2022 09:35:30:

            What is a Tens Machine ?

            Transcutaneous electrical nerve stimulation machine;

            Russell

            #608138
            John P
            Participant
              @johnp77052

              Google tens machine there are a lot of different circuit diagrams
              around for these things.

              Look at this and it will give an indication of how these things work.

              https://www.learningelectronics.net/circuits/transcutaneous-electrical-nerve_03.html

              John

              #608139
              Russell Eberhardt
              Participant
                @russelleberhardt48058
                Posted by BOB BLACKSHAW on 02/08/2022 07:30:04:My question is how can three AAA batteries have that power and last a long time in use. I've used the search on the forum with no results.

                The answer is that while the instantaneous power can be high the average power is low as a result of the pulses being short.

                Russell

                #608140
                Mike Poole
                Participant
                  @mikepoole82104
                  Posted by roy entwistle on 02/08/2022 09:35:30:

                  What is a Tens Machine ?

                  They are useful for blocking pain signals, often used by pregnant women for pain relief. Obviously they are useful for pain relief by men as well.

                  Mike

                  #608142
                  Anonymous

                    Used primarily for pain relief, but also used in BDSM and other erotic games. embarrassed

                    Although the voltages are reasonably high, tens to a hundred or so volts, the currents and duty cycles are low. Thus power ls low and AAA batteries are perfectly adequate.

                    Andrew

                    #608147
                    Clive Brown 1
                    Participant
                      @clivebrown1

                      Do you remember these?

                      #608158
                      SillyOldDuffer
                      Moderator
                        @sillyoldduffer

                        Hard to think of a way in which a TENS machine could cause a severe shock and even mild burns.

                        Burns require a high current to flow in the victim and a TENS unit doesn't allow that. A battery of small dry-cells power a low-voltage, low-current oscillator that pulses a step-up transformer to create mild electric tingle. (The tingle suppresses other pain by providing a counter-irritant. How well they work depends on the type of pain; anything between good and makes it worse. Well worth trying, but not a guaranteed miracle cure. )

                        The normal peak voltage is probably between 100 and 200V, but the amount of energy in each pulse is limited by the maximum current of the battery, the drive transistor, and the size of the transformer – all small.

                        Possibly a combination:

                        • Unit fitted with high capacity rechargeable or alkaline cells rather than dry cells with high internal resistances. (Allowing the battery to deliver much more current.)
                        • Condensation reduced the value of a resistor causing the oscillator to vibrate at higher than normal frequency. (Each pulse contains normal energy, but there are a lot more of them per second.)
                        • The higher than normal frequency happened to be resonant with the transformer causing exceptionally high voltage on the pads.

                        Although such a malfunction might deliver a surprising extra shock, especially to a damp victim, I'm still surprised a TENS unit caused visible damage. They aren't Widow Makers!

                        Condensation might explain why the unit is working normally now. Drying out would return the oscillator to it's correct operating range.

                        If condensation was the cause, the effect was downright unlucky because damp circuit boards are unlikely to work at all!

                        Dave

                        #608166
                        BOB BLACKSHAW 1
                        Participant
                          @bobblackshaw1

                          If the Tens pads are on my back for 24 hrs or more a visible and skin change in texture occurs, this is why I think up to date Tens have a max of 30 minutes. At the time of that full power shock I wished I took a photo of it as the marks were viable for a week or so. I use the Tens on 4, the most I can stand is 7, no way can I take 10. They are recommended for use with arthritis and strains, but not a cure just pain relief. In my opinion they are cheap to buy and no need for Paracetamol or any over the counter pain relief.

                          Bob

                          #608170
                          blowlamp
                          Participant
                            @blowlamp

                            Just got a TENS machine myself and I must say it is quite effective in blocking the back ache/sciatica I'm having at the moment.

                            The unit I have can be switched between 10-60 minutes in duration, with a default of 20.

                            There are about 20 programmed settings which can be varied in their intensity, but I find about 70% power output to be good for me.

                            I too experienced a couple enormous shocks the other day and thought that was due to me trying one of the other programmes, but it actually turned out to be that the gel pads weren't fully plugged in, so I'm assuming the unit must have generated a voltage sufficient to jump the gap. disgust

                            Martin.

                            #608196
                            modeng2000
                            Participant
                              @modeng2000
                              Posted by Clive Brown 1 on 02/08/2022 10:18:09:

                              Do you remember these?

                              Yes, I had one devil

                              #608198
                              Harry Wilkes
                              Participant
                                @harrywilkes58467

                                When mine old one gave up after many years I purchased one from Lloyds chemist and glad to say it was not that expensive it does as you say have more options

                                H

                                #608200
                                Russell Eberhardt
                                Participant
                                  @russelleberhardt48058
                                  Posted by modeng2000 on 02/08/2022 15:55:45:

                                  Posted by Clive Brown 1 on 02/08/2022 10:18:09:

                                  Do you remember these?

                                  Yes, I had one devil

                                  That's a smaller version of the "Trembler coil" used in the ignition of the Ford Model T motor car.

                                  Russell

                                  #608221
                                  Jon Lawes
                                  Participant
                                    @jonlawes51698

                                    I've used TENS for phantom limb pain and once when one pad was slightly dry it did leave a small burn.

                                    #608232
                                    Andy Stopford
                                    Participant
                                      @andystopford50521

                                      I also found that the effect was considerably more powerful if one of the pads became unplugged or fell off, no burns though.

                                      I bought it when I had killer sciatica last year, and it made my evenings much more bearable (sitting down was when the pain was worst). Martin's one sounds similar – I tried all the different settings at first but settled on the basic one at about 2/3 power and restarted the thing whenever it timed out – just having it running was more important than the level, and using maximum power definitely falls into the more… adventurous category of use as mentioned by Andrew.

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