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Double window motor/generator build journal

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  • #31
    Bradley, the halls I have used were only rated at 15V max so hence the voltage dividers. Also, not sure of which circuit you are running but the one I have will allow running the motor at 36V - so you definitely need the voltage dividers if you're going to run at that voltage.

    John K.

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    • #32
      I have some hard readings this time! I am using the flat copper coil on top of the drive coil as a generator/load. The charge times are for a 13.5v 5F cap bank (5x2.7v).

      Unloaded
      speed-5,700 rpm
      current-0.778 amps

      Loaded
      speed -4,380rpm (needs to be 3800 to make 2/3)
      current from battery-0.695 amps(times 13 volts on the battery = 9.035 watts)
      output from drive coil - 3 seconds to reach 5 volts...5 seconds to reach 9volts...and 7 seconds to reach 10 volts (this is with the gen/ load shorted)
      output from gen/load- measured with my multimeter it reads 0.628 amps at 6.58 volts (5 seconds to 3 volts...9 seconds to 4 volts...18 seconds to 5 volts)

      If I go with 5 seconds...9.035 watts would make 45.175 joules out. In that same five seconds the gen/load charges a 5F bank to 3volts = 22.5 joules along with the recovery from the drive coil also outputting 9 volts into the 5F bank =202.5 joules! I measured everything a few times...so if the math is correct and the online calculators I used were accurate that gives me 225 joules out using 45.175 joules in so I have an excess of 179.825 joules. So where did i measure wrong...i know its not this easy . I need to get a larger cap bank so i have longer to measure times so it would be more accurate but I took the cap charge readings 5 times along with current draw and speed. I believe the measurements are correct but is my math?

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      • #33
        Sequential Bipolar Switch - Commutator.jpgFound the error. the initial surge of current to get the motor going was also charging the caps...witch leads me to this. If there is a bridge accross the coil then any time you power the coil you are also powering anything connected to the bridge so instead of it being "cemf" its just power from the battery so I am confused. When there is a cap accross the bridge it slows the motor considerably until it is charged. I have heard of people charging a cap then pulsing the battery ...but the motor would be constantly speeding up and slowing down! Or is that the idea behind charging higher than the batt voltage then discharging back to 12? because if the cap has 12 volts than a 12 volt source would not put any more power in but the back cemf would still keep charging.

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        • #34


          This is a timing disc for a window motor. it has 10 magnet holes for mags. will fire hex rotor or square rotor, so you can do 2. 4 or 6 sided rotors. will have a 4/40 tapped hole for an allen set screw. next is hall sensor mounts, then end plates, then a rotor. this part took 2hrs and 53 minutes to print, solid infill, in ABS which is stronger than PLA. need to work a bit on infill and some other settings to get it a bit lighter, but still strong and warp free.

          I can make these for whatever number of timing holes and diameter needed. a 5 inch one would be great for a 16 or 21 magnet rotor.... If you all could think a bit about what you would want I can work up some drawings and pricing for them. anyone that has a printer already, send me a P.M. I will send you the STL file to play with.

          Thanks to ortho for his help on this part!

          I think 3D printing is really going to help us move this technology forward.

          Tom C
          Attached Files
          Last edited by Tom C; 04-01-2015, 07:52 AM.


          experimental Kits, chargers and solar trackers

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          • #35
            Originally posted by Tom C View Post
            This is a timing disc for a window motor.

            I think 3D printing is really going to help us move this technology forward.

            Tom C
            Thats cool Tom
            Mike

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            • #36
              Thanks again tom.
              https://www.youtube.com/watch?v=hWQ7...ature=youtu.be
              just to see i used a bifilar coil from an old pulse motor and hooked it up to the B/C circuit. draws somewhere close to half an amp and spins the rotor at about 28,000.

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              • #37
                geez that is fast...

                Tom C


                experimental Kits, chargers and solar trackers

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                • #38
                  Tom, how much would you want for a 2 magnet timing wheel and a three. I think 1/4 inch shaft i'll check on that.

                  at the moment i am using only 1 magnet to turn on each side of the B/C but i would like to have one with north facing out so i can put a hall backwards to try a few things without effecting the switching of the b/c.

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                  • #39
                    I can print whatever shaft size you want and whatever magnet spacing you want. I just need to know what your magnet diameter is so I can make the holes correct, and make sure the disc is big enough that the hall will switch off. its about 20 bucks each to print. includes tapping the hole and the set screw allen. because of the way 3D printers do holes (segments instead or true radius like CNC) it needs to be fiddled with a little bit. I would rather print it tight and let you ream it a bit so it fits snug. you can drill for size and press the magnets in also. they will be indexed at 180 and at 120 degrees. need to know magnet thickness if you are using both sides of the magnet so it is flush with both sides of the disk. or if you want you can just glue them on the face with 2 part epoxy... not as precise but it works. I have some abs filament called toner plastic that is really nice, I am making a bunch of stuff out of it.

                    Tom C
                    Last edited by Tom C; 07-17-2015, 01:15 PM.


                    experimental Kits, chargers and solar trackers

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                    • #40
                      Thanks...I'll get in contact whith you when I have the money and I take some measurements. I have been adjusting the halls instead of the timing wheel and the sweet spot is just to dang precise to be repeatable with what I am doing. a set screw timing wheel would be a large improvement!

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                      • #41
                        ok let me know...

                        T


                        experimental Kits, chargers and solar trackers

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                        • #42
                          here ya go!

                          Attached Files


                          experimental Kits, chargers and solar trackers

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                          • #43
                            Double window motor/generator build journal

                            i got 2 questions for ja how much did your mill cost.And when your done with the 540 mini-t plate could you scan it and give me the actual size so i could try to cut one out my selph?

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