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Quick hall effect sensor + mosfet conversion to sg wheel

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  • Quick hall effect sensor + mosfet conversion to sg wheel

    decided to try out hall switching before my next build so i grabbed the junk box and pulled apart some fans and got the hall sensor out and connected them to a mosfet driving an SG bike wheel.
    seems to work as i expected, needs an astable, pulse width is quite long, charging seems good but the battery is pretty dry and sulphated.

    http://vid936.photobucket.com/albums...ps223c2aff.mp4

  • #2
    Thanks for sharing

    Have you schematic ?

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    • #3
      mosfet sg.JPG

      it needs a timer to change the pulse width, and an opto isolator if you are going to run higher than 12 - 14v

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      • #4
        mosfet sg monostable.JPG

        circuit i will build next. one with resistors before holding pin 2 high is correct
        Attached Files
        Last edited by bigmotherwhale; 09-02-2014, 02:38 AM.

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        • #5
          Thank you for your time

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          • #6
            Hi BMW,

            Originally posted by bigmotherwhale View Post
            decided to try out hall switching before my next build so i grabbed the junk box and pulled apart some fans and got the hall sensor out and connected them to a mosfet driving an SG bike wheel.
            seems to work as i expected, needs an astable, pulse width is quite long, charging seems good but the battery is pretty dry and sulphated.
            I rigged mine up with two hall switches in series on separate adjustable mountings. This allows me to adjust both the timing and pulse width mechanically without using a 555 timer circuit. It seems to work best at about 20 percent on time. I use a small signal transistor in the base circuit of the 21194 power transistors.
            Last edited by Gary Hammond; 08-22-2018, 01:52 PM. Reason: change percent sign to word

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            • #7
              good idea, also using 21194 seems like a good plan, i will see how long my mosfets hold up.

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              • #8
                Any chance that some one could post the bedini SG schematic with a hall switch substituted for the trigger wire, I would like to see the difference but don't quite know how to do that.


                [QUOTE=Gary Hammond;16842]Hi BMW,

                Originally posted by bigmotherwhale View Post
                decided to try out hall switching before my next build so i grabbed the junk box and pulled apart some fans and got the hall sensor out and connected them to a mosfet driving an SG bike wheel.
                seems to work as i expected, needs an astable, pulse width is quite long, charging seems good but the battery is pretty dry and sulphated.

                QUOTE]

                I rigged mine up with two hall switches in series on separate adjustable mountings. This allows me to adjust both the timing and pulse width mechanically without using a 555 timer circuit. It seems to work best at about 20 percent on time. I use a small signal transistor in the base circuit of the 21194 power transistors.

                Comment


                • #9
                  Hi Brian,

                  Give me a few days and I can post a schematic of what I did. I'm currently away from home on a mini vacation and posting this from a motel room using my wife's laptop.

                  cheers,

                  Comment


                  • #10
                    Thank you, hope you have a nice vac.

                    Originally posted by Gary Hammond View Post
                    Hi Brian,

                    Give me a few days and I can post a schematic of what I did. I'm currently away from home on a mini vacation and posting this from a motel room using my wife's laptop.

                    cheers,

                    Comment


                    • #11
                      the monostable circuit is useless, the input pulse duration affects the output pulse duration, back to the drawing board

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                      • #12
                        problem solved, mosfet isolation driver stage next.http://vid936.photobucket.com/albums...ps3cc1ee71.mp4

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                        • #13
                          sucess, variable pulse width and timing, mosfet driven simply from optocoupler but not yet ready for high voltages, it produces the biggest spikes, and i cant dampen them enough with a battery to stop the neon protection on the mosfet from staying on, without the battery the neon is not yellow but bright blue / white.
                          the wheel spins a reasonable speed with a very small duty cycle at around 200ma including the switching and i only have a single coil winding out of 8 connected (140ft x 0.5mm)

                          http://vid936.photobucket.com/albums...ps6a2fd9bd.mp4

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                          • #14
                            I always thought that one of the essential essences of the SG is that it does not need or want a Hall sensor. Am I wrong?

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                            • #15
                              Originally posted by wrtner View Post
                              I always thought that one of the essential essences of the SG is that it does not need or want a Hall sensor. Am I wrong?
                              In a way you are spot on it is a 'school girl circuit' a bit sexist i suppose! however i think the idea was to create the "effect" as simply as possible, anyone can create the SG circuit without any electronics knowledge at all, making a good setup with a hall or optical really needs a scope and some basic electronics knowledge.
                              the amount of inductive kickback with this circuit is higher than i have seen with any inductively triggered circuit (on the same spool).
                              JB says that you have to build at a higher level if you want to go further, the sg is just a simple introduction to the idea.
                              I will post my final simple schematic so everyone can have a go, my first one was incomplete so dont bother with it.

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