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  • Alternative popper mod suggestions

    Hi everyone.
    Im new to roasting. Did a few roasts on the weekend in an unmodified cornelius popper (coffeenelius?). First crack was happening at 2min and second at 4-5min so Im looking at ways to slow it down a bit.

    Im looking at a couple of ideas.
    One is to speed up the fan because its only running at 16V but its built for 24. I think i can increase the voltage across it by increasing the resistance that controls this (thats the resistance across the smaller heating element). So Id wanna add in a variable resistor (potentiometer/rheostat) between the circuit board and the small heating element. Higher resistance here = higher voltage in to the fan.

    I Dont want to burn out the fan so Ill need a constant resistor in there too, in parrellel to the variable one. This puts an upper limit on the extra voltage, whatever I do with the the knob i cant take the fan past 24V.

    Ive done a bit of maths and I need the constant resistor to be 1.5 ohms and able to take 34 watts of power. The variable resistor needs to be able to take 17 watts and needs to give me control between zero and maybe 10 ohms but it doesnt matter if it goes a bit higher.

    Could this work?
    Does anybody have any suggestions where to buy the bits? I could get a gang of 4 resisters (10Watts) for $2 each from jaycar but not the variable resistor. I like to scrounge electrical parts so best of all would be a tip on what to take apart (knobs from electric stoves maybe?)

    Thanks,
    Conan

  • #2
    Re: Alternative popper mod suggestions

    Im no electronics expert but from what Ive read the fan and heater circuits are linked.
    Your idea may do something to the heater that you dont want it to.

    I found the easiest way to slow down a roast by introducing more air was to allow as much air as possible in (look underneath) and to let out heat trapped in the body by adding large holes or removing the top half altogether.

    Im not sure if you can remove the top of a cornelius like you can with a Crazy Popper.

    Comment


    • #3
      Re: Alternative popper mod suggestions

      Welcome home to roast.... [smiley=thumbsup.gif]

      Potentiometer control of the fan speed is not the way to go, far better to split from the voltage divider that are the heating element sections and use a suitably rated transformer driven by an electronic ceiling fan controller.

      Lots of info to be found on this site and others by doing a Search...

      Personally though, Id give TGs ideas a go first since this will get the basics taken care of without the need for electrical circuit intervention, and may well be all that you need to do.... 8-)

      Mal.

      Comment


      • #4
        Re: Alternative popper mod suggestions

        adding resistance will lower the voltage across the motor you want to lower the heater resistance so more voltage is across the motor, it basically a voltage divider with the heater running on 220 and the motor on the remainder about 20V,

        if you lower the the heater resistance  by cutting a bit off or shorting part of heater together,  there will be more voltage across the motor , but lowering the heater resistance may also cause the heater to run hotter , its a fine balancing act, both heater and motor have been chosen to work well together as they are, will it cool more or heat more if you alter heating resistance / motor voltage?

        here is a calculator you can try different values to see what you need to do.

        http://www.raltron.com/cust/tools/voltage_divider.asp


        for E  x I = W ,  240V x 5A = 1200W Heater
        E = I x R , 240V = 5A x 48R , total resistance.

        E=I x R , 20V = 5A x 4R  Motor

        E=I x R, 220V = 5A x 44R Heater

        just some approx values for example.

        You also have some voltage drop across the full wave diodes to generate the DC for motor , but it can probably be ignored.

        best to use electronic fan and/or heater controller.









        Comment


        • #5
          Re: Alternative popper mod suggestions

          what about separating the two: Fan <-> heat and using a couple of phase angle controllers or triac based power controllers ?

          then you can turn the AC up and down to whatever you need


          how about a phase angle controller on the heat
          and a 600w dimmer (light switch dimmer) on the fan ?

          but if your ordering one P-Angle just get two....

          not really sure if it will work on the fan

          seems overkill on a popper but...

          Comment


          • #6
            Re: Alternative popper mod suggestions

            Adding my 2c.
            On my 15year old Black & decker Popper, the resistance wire that drops the voltage for the fan is not used for heating the chamber. As it is not in the air flow path, it has no direct heating effects.
            As you can see in the picture below, I have taken out all the heat safety devices and bridged the contacts.

            The two outer pins are the heaing element, and the inner (not connected) pin is one end of the fan resistance wire.

            I run my heater element on full power, and only vary my fan speed.
            Fan is controlled by a Jaycar 12+12v 5A transformer which is varied by a 400W light dimmer.

            My roasts can be stretched to whatever time I want.

            Have safe fun.
            Dan.



            Comment


            • #7
              Re: Alternative popper mod suggestions

              Hi Dan....

              This may be the design of the B&D but with others I have stripped down, they split the heating element and use it as a voltage divider, with one section feeding the fan motor - Anything from 15-28V. Providing advice is OK but if youre going to delve into the nitty gritty, you need to make sure youre dealing with identically designed systems or disaster may follow for the recipient of that advice...

              Mal.

              Comment


              • #8
                Re: Alternative popper mod suggestions

                if the heating element is tapped you could rivet the motor contact higher up to increase the voltage of the tap off point.

                best to carefully examine what type of popper circuit you have and then work out what you can do.

                Comment


                • #9
                  Re: Alternative popper mod suggestions

                  this guy suggested opening the side vent holes  for better airflow.
                  have not seen this mentioned before. simple and easy to do, and with better venting of outer case should increase airflow a lot.

                  http://sites.google.com/site/garybt3/thepopcornpumper

                  internal side vent holes in metal wall of popper.

                  Comment


                  • #10
                    Re: Alternative popper mod suggestions

                    Originally posted by 54797D717C100 link=1292323422/6#6 date=1292375336
                    Hi Dan....

                    This may be the design of the B&D but with others I have stripped down, they split the heating element and use it as a voltage divider, with one section feeding the fan motor
                    In all the poppers Ive stripped down, of various makes, they have all been wired the same. They have all had 2 elements, the outer larger diameter wound wire thats in the airflow (as you can see in the above photo), and another smaller diameter wound wire inside the outer one (cant be seen in the photo). The 2 elements are connected together, end to end.

                    They all had 3 wires going to the heater (as in the above photo) - lets call them wire A, B & C. Wire A connects to one end of the main heater element. Wire B connects to the other end of the main element and also to one end of the resistor wire for the fan, ie. both inner and outer elements connect at this point. Wire C connects to the other end of the resistor wire for the fan (inner element). To run the main outer heater element only, all you have to do is connect A to one side of 240V and B to the other side of 240V. Current then only flows between A and B, ie. both ends of the outer main heater element. As we leave C unconnected, no current flows between B and C, ie. the resistor wire for the fan does nothing.

                    Comment


                    • #11
                      Re: Alternative popper mod suggestions

                      Yes mate....

                      What you say is correct but the elements are configured as a voltage divider, not as an element with a separate dropping resistor for the fan motor supply; that is the only point I was trying to make. My background is Electrical Engineering by the way.....

                      Mal.
                      P.S.
                      Just dug out a thumbnail sketch made of an early Tiffany Popper. Explains what Im talking about...

                      Comment


                      • #12
                        Re: Alternative popper mod suggestions

                        Originally posted by 4F607B6C79667E6C7B090 link=1292323422/8#8 date=1292411816
                        this guy suggested opening the side vent holesfor better airflow.
                        have not seen this mentioned before.
                        What about my post above?

                        Originally posted by 5D617C676D6C7B6E666D090 link=1292323422/1#1 date=1292332126
                        I found the easiest way to slow down a roast by introducing more air was to allow as much air as possible in (look underneath) and to let out heat trapped in the body by adding large holes or removing the top half altogether.
                        (not to mention dozens of posts in dozens of previous threads)

                        Comment


                        • #13
                          Re: Alternative popper mod suggestions

                          Originally posted by 14393D313C500 link=1292323422/10#10 date=1292418175
                          My background is Electrical Engineering by the way.....
                          Yes, I know.....  :

                          I agree with you. Ok, maybe I was wrong to refer to the inner element as the resistor for the fan. Call that element whatever you like though, the only point Im trying to make is that you dont need to use that element. The poppers do run fine on just the outer element. I know because Ive done it, on a few different poppers. Thats all Im saying - if youre powering the fan separately, for heating you only need to use wires A & B for the outer wire coil, you dont need to use C.

                          regards,
                          Bill

                          Comment


                          • #14
                            Re: Alternative popper mod suggestions

                            Originally posted by 1D30343835590 link=1292323422/10#10 date=1292418175
                            Just dug out a thumbnail sketch made of an early Tiffany Popper. Explains what Im talking about...
                            Yep, that looks like the ones Ive had. So all Im saying is if you are powering the fan separately, you only need connect what you have labelled "main element", you can bypass "aux. elem."

                            Comment


                            • #15
                              Re: Alternative popper mod suggestions

                              Yes mate, I knew what you meant but for non-electrical people it is very confusing....

                              Mal.

                              Comment

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