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    Dimmer conspiracy

    It seems that many (most?) Dimmers only put out about 90% of line side voltage Does anyone else know about this?
    Ethan Brush - East West Electric. NY, WA. MA

    "You can't generalize"

    #2
    Originally posted by electrofelon View Post
    It seems that many (most?) Dimmers only put out about 90% of line side voltage Does anyone else know about this?
    Well, there may be a diode droo or two, and a two terminal phase controlled dimmer has a hard task trying to maintain 100% conduction. It may be a consequence of inexpensive circuitry. Are you measuring with a true RMS meter? An averaging meter will give undue weight to the cutoff sections near the zero crossing.

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      #3
      190813-1333 EDT

      A scope clearly shows the effect.

      A phase shift dimmer essentially detects the time of a zero crossing, and initiates a time delay to triggering of the switch. This minimum time delay becomes a practical problem.

      Probably the shortest possible time delay is set by a constant continuous current to the gate, and then the delay is a result of the characteristics of the switch. About a 1 volt switch voltage drop. At 1 V and a 120 V sine wave this is about arc sine of 1/170 = 0.24 degrees.

      .

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        #4
        Meter is a klein branded true RMS meter so not the highest quality of course, but should be accurate. Dimmer is a lutron Caseta. Client said he heard about this and I was skeptical at first but a believer after I metered it with and without the dimmer.. they do have a high trim adjustment, but he said he had it set to max. I should have verified this but I didn't.
        Ethan Brush - East West Electric. NY, WA. MA

        "You can't generalize"

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          #5
          190814-2341 EDT

          electrofellon:

          I expect that you will find that virtually all commercial phase shift dimmers will show less than full voltage when set for maximum brightness.

          .

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            #6
            Originally posted by gar View Post
            190814-2341 EDT

            electrofellon:

            I expect that you will find that virtually all commercial phase shift dimmers will show less than full voltage when set for maximum brightness.

            .
            And not as part of some energy saving conspiracy, but as a necessary consequence of economical design.

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              #7
              Originally posted by GoldDigger View Post

              And not as part of some energy saving conspiracy, but as a necessary consequence of economical design.
              I know Obama, the other libs, and big solar are behind this! So you really think it is just a coincidence that as soon as I bring this up, the forum get "upgraded" so everyone is all confused and disheveled so not as many people read this post!?!? Just kidding But seriously, it is interesting that few people seem to know about this.
              Last edited by electrofelon; 08-15-19, 06:34 AM.
              Ethan Brush - East West Electric. NY, WA. MA

              "You can't generalize"

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                #8
                Any p-n junction will cause a voltage drop of ~0.7volts. Who knows how many junctions the power in a dimmer has to pass through to get to the other side!

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                  #9
                  This shows some interesting info on dimmers:

                  https://youtu.be/z_gC_GXVL4w

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                    #10
                    Originally posted by synchro View Post
                    This shows some interesting info on dimmers:

                    https://youtu.be/z_gC_GXVL4w
                    Good info
                    Ethan Brush - East West Electric. NY, WA. MA

                    "You can't generalize"

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                      #11
                      Originally posted by electrofelon View Post

                      I know Obama, the other libs, and big solar are behind this!
                      Just use bigger bulbs!

                      -Hal

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                        #12
                        You didn’t know this?
                        I thought it was more like 95% but it was enough that it could be slightly noticed in light output between hooking direct or installing dimmer.
                        I've known this since I was knee high to a grass-hopper, just the effects of being controlled by electronics.
                        But on the up-side, lamp life was extended just by installing a dimmer even if it was kept on high. Probably why many of the 65watt R30 lamps used in my can lighting are still in use today.

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                          #13
                          Originally posted by electrofelon View Post

                          I know Obama, the other libs, and big solar are behind this! So you really think it is just a coincidence that as soon as I bring this up, the forum get "upgraded" so everyone is all confused and disheveled so not as many people read this post!?!? Just kidding But seriously, it is interesting that few people seem to know about this.
                          I could see that some may think it is possible that the solid state portions get bypassed when in full brightness position.
                          I live for today, I'm just a day behind.

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                            #14
                            Originally posted by kwired View Post

                            I could see that some may think it is possible that the solid state portions get bypassed when in full brightness position.
                            By adding a hardware switch at the max on position that could be done. Or by using a relay. But the users will see a jump from max variable to bypass/full. And it will be more expensive and harder to fit into a single gang format.

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                              #15
                              There used to be a dimmer that looked like a standard toggle switch, but the toggle was actually the dimmer control. It had both mechanical-switch off and mechanical-switch fully-on bypass.

                              If 100% voltage is a requirement at times, parallel the dimmer with a switch.
                              Master Electrician
                              Electrical Contractor
                              Richmond, VA

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