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Popper mods for extending roast times

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  • #16
    Re: Popper mods for extending roast times

    Originally posted by Mal link=1190848096/0#14 date=1191152491
    Gday Bill,

    I reckon those two devices would do a good job from the little info that is available from the specs. Grab the smallest Motor Control Unit and the 2KW Light Control Unit and that should cover pretty well everything youre likely to roast. Youll still need to get a 50VA Step-Down Transformer (Txfmr) for the fan though and use the controller on the Primary side of the Txfmr. That way, youll be able to manage a fairly useful variable output to the fan motor. Naturally, the Output from the 2ndry side of the Txfmr needs to be rectified to DC to suit the DC Motor requirements.

    Should work well though ....

    Mal.
    Hi Mal,

    Ive already got a "General Purpose Multitap AC/AC Transformer 12 - 30V @ 2 Amps" from Dick Smith. Refer http://www.dse.com.au/cgi-bin/dse.storefront/46ff8fc6024512f8273fc0a87f9c072b/Product/View/M1991
    Seems to work fine on the 20V connection. Would it be safe to go to higher volts to enable a higher bean load?

    Well the smallest motor speed controller that that previous site has is a "230V MOTOR SPEED CONTROLLER 375W" but on the technical specs sheet it states "The module only accept universal engines. Don’t control inductive loads as fluorescent halogen lamps, transformers, etc...". Would this be ok, or what else would you recommend?

    thanks,
    Bill

    Comment


    • #17
      Re: Popper mods for extending roast times

      Gday Bill,
      in relation to your enquiry about the photos of my controller.
      The dimmer switch is only being used as a housing to hold the potentiometer on the circuit I built, which adjusts the temperature. It just makes it fit into a standard switch plate more easily, the actual dimmer is history.
      The 2000W light regulator looks like it will handle the power of the popper heating coil without any problems.
      After reading the spec sheet for the motor speed controller, it looks like it may struggle with the transformer, as it is an inductive load.
      A variable fan speed controller will handle the transformer, and it would work out about the same price as the motor speed controller, once you factdr in postage and the exchange rate.

      On a sad note, I actually dont have the circuit diagrams any more as my computer crashed about 6 months ago now, and of course I didnt make back ups of anything :-[.
      The hard lessons are always the best ones .
      All the best with it.

      Comment


      • #18
        Re: Popper mods for extending roast times

        Thanks Lovey.

        So what did you have to do to be able to roast 200gms in it? Are you running the fan severely over-volted, or have you done some mods to increase airflow, or both? Can you provide more details of what you did please?

        thanks,
        Bill

        Comment


        • #19
          Re: Popper mods for extending roast times

          Originally posted by Bill link=1190848096/15#17 date=1191215546
          Thanks Lovey.

          So what did you have to do to be able to roast 200gms in it? Are you running the fan severely over-volted, or have you done some mods to increase airflow, or both? Can you provide more details of what you did please?

          thanks,
          Bill
          Gday Bill,
          I just ran the fan over voltage to increase its airflow. One thing to remember is that if the heat is reduced, the air flow can be a bit lower as the bean mass retains a lot of heat as there is less air flow through it. You could probably get away with using a fixed fan speed and controlling the heat using that light regulator, but that would limit the upper and lower limits of how much you could roast.

          Comment


          • #20
            Re: Popper mods for extending roast times

            Originally posted by Lovey link=1190848096/15#18 date=1191219719
            Originally posted by Bill link=1190848096/15#17 date=1191215546
            Thanks Lovey.

            So what did you have to do to be able to roast 200gms in it? Are you running the fan severely over-volted, or have you done some mods to increase airflow, or both? Can you provide more details of what you did please?

            thanks,
            Bill
            Gday Bill,
            I just ran the fan over voltage to increase its airflow. One thing to remember is that if the heat is reduced, the air flow can be a bit lower as the bean mass retains a lot of heat as there is less air flow through it. You could probably get away with using a fixed fan speed and controlling the heat using that light regulator, but that would limit the upper and lower limits of how much you could roast.
            So what voltage are you running the fan on to roast 200gm?


            thanks,
            Bill

            Comment


            • #21
              Re: Popper mods for extending roast times

              Originally posted by Bill link=1190848096/15#19 date=1191220393
              So what voltage are you running the fan on to roast 200gm?

              thanks,
              Bill
              I was using a 30V secondary transfomer and allowing for losses, the maximum voltage I could get at the motor was about 26V. I didnt use to run the motor that hard for long though, just enough to get the beans moving.
              As the beans advance through the roasting process, they lose moisture and get lighter, so the throttle would have to be cranked back a bit to stop them flying out the top of the chimney as the roast goes on ;D.

              Comment


              • #22
                Re: Popper mods for extending roast times

                Originally posted by Lovey link=1190848096/15#20 date=1191222768
                Originally posted by Bill link=1190848096/15#19 date=1191220393
                So what voltage are you running the fan on to roast 200gm?

                thanks,
                Bill
                I was using a 30V secondary transfomer and allowing for losses, the maximum voltage I could get at the motor was about 26V. I didnt use to run the motor that hard for long though, just enough to get the beans moving.
                As the beans advance through the roasting process, they lose moisture and get lighter, so the throttle would have to be cranked back a bit to stop them flying out the top of the chimney as the roast goes on ;D.
                Thanks for the info. Id only been game enough to put 20V to the regulator so far. Ill try increasing it a bit at a time to 30V and see how it goes. Yes, I suppose it would only need to run at full speed for the first few mins of the roast until the beans lost some moisture.

                What fan speed controller are you using? Something "off the shelf", or did you have to build it?

                thanks,
                Bill

                Comment


                • #23
                  Re: Popper mods for extending roast times

                  Originally posted by Bill link=1190848096/15#21 date=1191226053
                  Thanks for the info. Id only been game enough to put 20V to the regulator so far. Ill try increasing it a bit at a time to 30V and see how it goes. Yes, I suppose it would only need to run at full speed for the first few mins of the roast until the beans lost some moisture.
                  You gont go near 30V DC at the motor with a 30V secondary transformer due to various factors. If you want the calcs to work out the voltages I can PM them to you if you like.

                  What fan speed controller are you using? Something "off the shelf", or did you have to build it?
                  It was an off the shelf HPM brand fan speed controller. Make sure you get one with the variable speed, and not the 3 speed switch.

                  Comment


                  • #24
                    Re: Popper mods for extending roast times

                    Originally posted by Lovey link=1190848096/15#22 date=1191227415
                    You gont go near 30V DC at the motor with a 30V secondary transformer due to various factors. If you want the calcs to work out the voltages I can PM them to you if you like.
                    No, no. I was referring to the AC voltage at the transformer. I have a multitap transformer, so I can select 20V, 24V, 27.5V, or 30V AC depending on what connection I use off the transformer. Yes, the voltage drops down from that after it goes through the rectifier attached to the fan.


                    Originally posted by Lovey link=1190848096/15#22 date=1191227415
                    It was an off the shelf HPM brand fan speed controller. Make sure you get one with the variable speed, and not the 3 speed switch.
                    Ok, so you mean its one of those standard domestic ceiling fan controllers like youd find at the hardware store? Does that give you a good range of control over the speed?


                    thanks,
                    Bill

                    Comment


                    • #25
                      Re: Popper mods for extending roast times

                      Originally posted by Bill link=1190848096/15#23 date=1191239853
                      Ok, so you mean its one of those standard domestic ceiling fan controllers like youd find at the hardware store? Does that give you a good range of control over the speed?
                      thanks,
                      Bill
                      I got mine from the local hardware shop, I think it was about $45 from memory. It gives a good range of speed from stalling, right up to flat stick.

                      Comment


                      • #26
                        Re: Popper mods for extending roast times

                        Originally posted by Lovey link=1190848096/15#24 date=1191310785
                        Originally posted by Bill link=1190848096/15#23 date=1191239853
                        Ok, so you mean its one of those standard domestic ceiling fan controllers like youd find at the hardware store? Does that give you a good range of control over the speed?
                        thanks,
                        Bill
                        I got mine from the local hardware shop, I think it was about $45 from memory. It gives a good range of speed from stalling, right up to flat stick.
                        Ok, thanks for all the advice.

                        My roast I did on the weekend turned out great! It was the first roast Ive done with the heating and fan circuits separated on to separate switches. My best roast so far! I cant wait until I get the adjustable controls - I just ordered the 2000W dimmer last night.

                        Oh, I tried upping the voltage to the fan as you suggested and with 27.5V AC (highest Ive tried so far) could easily get 160gm of greens spinning in the chamber. I only ran it for a few secs though, just to test it out.


                        thanks again,
                        Bill

                        Comment

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