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  • Popper mods for extending roast times

    Thanks to the suggestions by other CS members on extending roast times in a popper, I have incorporated a few of these mods to my popper and did one roast one it. Results were promising, though hardly conclusive at this stage. Roasted an 80g batch of Swiss Water P Decaf beans at 6pm, and FC registered at 420", pretty much the same as if I did it at 9:30pm without the mods and at lower ambient temps. Pulled the roast at 1030" and never really got to hear 2nd Crack. Then again, Decaf beans cracks are especially hard to detect.
    I have also taken pics and will post them. First up, equipment list:
    1. Breville Crazy Popper with the plastic top half of the housing removed and bottom cover removed as well.
    2. A square fan unit - mine was a 240V one recovered from a de-installed outdoor Mobile Base station cabinet, you could use a PC one I suppose.
    3. A soup can from Campbells Chunky - cleaned and the bottom cut out with a can opener.
    4. 2 way plug (1 for fan, 1 for popper)
    5. Milk crate turned upside down (not in pic) for fan to rest on.


  • #2
    Re: Popper mods for extending roast times

    The top half can be removed easily if you know how. Took me a good 20 minutes to figure it out. The 4 screws that hold down the top plastic housing is protected by a hard plastic plug thing that doesnt come out easily. Obviously, the makers didnt want people removing it. Tried to pry it out with a small screwdriver, knife etc.. Eventually, I screwed in a self-tapping screw and used a plier to lever it out (Pretty much like how you remove the group gasket on the silvia). Once thats out, the whole thing is easily removed.
    I also remove the bottom, couldnt be bothered to drill holes in it. Next pic shows the bottom of the popper with the cover removed.

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    • #3
      Re: Popper mods for extending roast times

      Maybe the other plate above the PCB can do with a few more holes too. Anyway, I sat the fan below that so I figured it didnt matter too much.
      Next pic shows the soup can used for the chimney. Nothing overly fascinating about it EXCEPT that the top part of the can where the removable pull-out lid is fits EXACTLY over the popper chamber without any modification required! The groove in the can is of the exact diameter as the popper chamber... how good is that? Dont need a thing to secure the chimney on the chamber. With the top plastic housing on, I needed to cut slits into the bottom part of the can to fit the chimney but with the housing off...

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      • #4
        Re: Popper mods for extending roast times

        See that groove? Saves a lot of pain trying to make a can fit into a hollow aluminium chamber...
        This pic shows the complete setup but youll have to imagine it sitting on an upside down milk crate. The milk crate was outside and was not clean and so its entry into the house was forbidden. Pretty much, thats how it sat (above the milk crate that is) when I did my first test roast on it. You can see the fan sitting just under the popper blowing air into it to help cool it down a little and hopefully extend the roast times. After the roast is done, I just removed the popper and placed the colander with hot beans above the fan.

        Comment


        • #5
          Re: Popper mods for extending roast times

          Hi NewToEspresso

          That looks great. Did you have any trouble keeping the soup can in position - is it just sitting there or is it a press fit?

          The only addition I would make is to drill a small hole next to the earthwire on the chimney for a thermocouple probe.

          cheers

          jeff

          Comment


          • #6
            Re: Popper mods for extending roast times

            Its not a pressed fit but it stayed on the entire roast without even a hint of movement. Didnt matter that there were beans jumping around and coming in contact with the chimney, the chimney wasnt going anywhere.

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            • #7
              Re: Popper mods for extending roast times

              Great Tutorial NTE..... Definitely warrants a [smiley=tekst-toppie.gif]

              Mal.

              Comment


              • #8
                Re: Popper mods for extending roast times

                Yes good job.

                My exhaust pipe chimney originally was fitted to the CP with the top half of the body intact so after that mod it was a bit of a loose fit in the roasting chamber.

                I had to fit some clips over the edge of the chamber that took up the slack space and all was well again.

                Incase anyone else wants to do this mod it was easy to take out the plugs hiding the screws securing the top of the body.

                Just use a drill bit a smidge smaller than the plug and it will come away easily.

                Comment


                • #9
                  Re: Popper mods for extending roast times

                  Originally posted by NewToEspresso link=1190848096/0#1 date=1190848401
                  I also remove the bottom, couldnt be bothered to drill holes in it. Next pic shows the bottom of the popper with the cover removed.
                  NTE, you want to be very careful if you are leaving the bottom off the popper. Some of those exposed wiring connections are carrying 240V!

                  Ive been modifying my B&D popper at the moment. Its pretty easy to re-wire the fan and heating elements on to separate circuits, if you know what wires to connect (Ive had some advice from an electrical engineer that I work with). Your popper internals look very similar to mine actually. Im intending to put a light dimmer in to the fan circuit to control the fan speed, and also a high power dimmer to control the power to the heating element. For the fan circuit you can just use a standard domestic light dimmer, but for the heating circuit you need a pretty heavy duty dimmer as the heating circuit draws quite a lot of current. Im currently looking in to what dimmers are suitable for handing that amount of current and so far havent found anything suitable that doesnt cost hundreds of dollars. I may have to build one - Ive found a dimmer kit that is sold in the UK that can handle 2000W so I may get one of those. Anyway, I may post some photos and instructions later on when I get it all working. Currently Ive just got the fan and heating element circuits separated (fan powered by separate transformer) and that all works as its supposed to - just did 3 batches in it yesterday.


                  Bill

                  Comment


                  • #10
                    Re: Popper mods for extending roast times

                    Gday Bill,
                    just passing on some sage advice that Mal passed on to me when I was modding my popper. Youre better off using a fan speed controller than a light dimmer for controlling the speed of the fan circuit. Light dimmers dont like inductive loads, like motors running through them. You can get variable speed fan controllers from electrical wholesalers and quite a few hardware shops as well.
                    In relation to the high powered dimmer, take a look at the Too Much Coffee web site, theres instructions for how to modify an existing light dimmer to handle the extra power of the popper heater circuit. I started off using one of these successfully, but the urge to build my own circuit (with a lot of help from Mal) was too great. I knocked one up on a breadboard, and hey presto, a variable air speed and heat popper.
                    The standard disclaimers about playing with electricity apply of course, dont fry yourself.
                    Good luck with it.

                    Comment


                    • #11
                      Re: Popper mods for extending roast times

                      Originally posted by Lovey link=1190848096/0#9 date=1191130526
                      Gday Bill,
                      just passing on some sage advice that Mal passed on to me when I was modding my popper. Youre better off using a fan speed controller than a light dimmer for controlling the speed of the fan circuit. Light dimmers dont like inductive loads, like motors running through them. You can get variable speed fan controllers from electrical wholesalers and quite a few hardware shops as well.
                      In relation to the high powered dimmer, take a look at the Too Much Coffee web site, theres instructions for how to modify an existing light dimmer to handle the extra power of the popper heater circuit. I started off using one of these successfully, but the urge to build my own circuit (with a lot of help from Mal) was too great. I knocked one up on a breadboard, and hey presto, a variable air speed and heat popper.
                      The standard disclaimers about playing with electricity apply of course, dont fry yourself.
                      Good luck with it.
                      Ok, thanks Lovey. Ive seen other websites that have used a dimmer on the fan circuit, but dont know how well this worked. Another option may be to just use the different connections on my transformer to vary the voltage. I have a multi-tap transformer which allows me to vary the voltage anywhere from 12V to 30V depending on which connection I use. I could possibly use some sort of switch to change between the different voltage terminals.

                      Thanks for the mention of that other website. Thats led me to another UK site that has a kit for a 1500W motor speed controller for a bit less money than the 2000W dimmer I found. I think its probably better to buy a kit rather than making something from scratch because you know the design has been tested and works, and contains all the components you need.

                      thanks,
                      Bill

                      Comment


                      • #12
                        Re: Popper mods for extending roast times

                        Gday Bill,
                        after reading your reply, I realised that I made an error, sorry :-[.
                        The fan speed controller is actually used to control the primary side of a step down transformer, which then supplies the motor (after being rectified to DC).
                        The comment about the dimmer not liking inductive loads still stands though, as a transformer is an inductive load.
                        Have a look at this thread and it should give you some ideas.
                        http://coffeesnobs.com.au/YaBB.pl?num=1132286143/0#0
                        Hope this helps.

                        Comment


                        • #13
                          Re: Popper mods for extending roast times

                          Originally posted by Lovey link=1190848096/0#11 date=1191145906
                          Gday Bill,
                          after reading your reply, I realised that I made an error, sorry :-[.
                          The fan speed controller is actually used to control the primary side of a step down transformer, which then supplies the motor (after being rectified to DC).
                          The comment about the dimmer not liking inductive loads still stands though, as a transformer is an inductive load.
                          Have a look at this thread and it should give you some ideas.
                          http://coffeesnobs.com.au/YaBB.pl?num=1132286143/0#0
                          Hope this helps.
                          That popper of yours looks exactly like mine! I guess a lot of re-branding goes on.

                          In the photos in that thread of yours, that looks like a standard domestic light dimmer and standard domestic fan speed switch. Surely they wouldnt handle the load, but I suppose youve done some modifications to them. Can you provide more info please? PM me with the details if you like.

                          And how do you manage to do a 200gm batch, with enough fan power to be "chucking beans out of the chimney"? What voltage are you supplying to the fan? Before modifying mine I measured 18V AC going in to the rectifier on the fan. Ive upped that to 20V which has made me able to add an extra 10gms of beans, so now I can get 110gms, which is still quite a way from 200! Other sites from overseas have used 24V to the fan but I dont want to blow it up or anything!

                          thanks,
                          Bill


                          ps. I was thinking of using something like this for the heater control:

                          230V MOTOR SPEED CONTROLLER 1500W (http://cpc.farnell.com/jsp/Car,+Leisure+&+Hobbies/Electronic+Kits/CEBEK/R-10/displayProduct.jsp?sku=HK00472)



                          Comment


                          • #14
                            Re: Popper mods for extending roast times

                            or this:

                            230V LIGHT REGULATOR-2000W (http://cpc.farnell.com/jsp/Car,+Leisure+&+Hobbies/Electronic+Kits/CEBEK/I-16/displayProduct.jsp?sku=HK00467&_requestid=226007)


                            Comment


                            • #15
                              Re: Popper mods for extending roast times

                              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.

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