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  • Crazy Popper Mod Question

    Ive got a new Crazy popper and am thinking of controlling the heater with a pid controller.

    I understand that the heater and fan are in series with the heater dropping the voltage to a level usable by the fan.

    If I separate the heater and fan, will the heater then run hotter if it remains uncontrolled? Is this OK?

  • #2
    Re: Crazy Popper Mod Question

    Originally posted by greencardigan link=1205452241/0#0 date=1205452240
    If I separate the heater and fan, will the heater then run hotter if it remains uncontrolled?
    No, it wont. There are 2 heating coils. The larger, outer one, is the main heating element. That one is not in series with the fan, and is the only one you need to use. The smaller, inner one is the one used to drop voltage to the fan.

    You might mave some fun getting the Crazy Popper dismantled. I pulled one apart for parts and it was a nightmare! You cant access the screws as the circuit board is mounted over them. So it seems that you need to un-solder the circuit board from the fan motor before you can access the other mounting screws. My B&D popper was much easier to work on as it didnt have this problem.


    regards,
    Bill

    Comment


    • #3
      Re: Crazy Popper Mod Question

      Originally posted by greencardigan link=1205452241/0#0 date=1205452240
      I understand that the heater and fan are in series with the heater dropping the voltage to a level usable by the fan.
      As Bill has indicated, there is more to it than that......

      The actual circuit in most poppers Ive converted to roasters has the heating element set up as a Voltage Divider, i.e. there isnt a "dropping resistor" as such for the fan power supply, rather the voltage drop across a section of the element is used to power the fan. The two sections of the heating element are actually in series to accommodate this which means you cant really separate them and thereafter achieve the same heat output as previously attained.

      If you want to enjoy more control over the output of the popper, you basically just separate the fan supply wiring from the heating elements, leaving the elements as they are, acquire a suitable small transformer and install this such that the fan obtains its power supply from this. By visiting Bunnings or some similar store, you can then grab a solid state ceiling fan speed controller and feed the primary side of the fan transformer with this. By varying the output of the transformer, you then vary the speed of the fan which then allows you to maintain a limited degree of control over the heat output via the control of more or less airflow over the heating element.

      If youre not qualified to work on 240V AC equipment, then I would leave all this well enough alone as 240V can and does kill people all the time. Instead, find a local Sparky who shares the same interest in high quality coffee as you and offer to roast him/her a Kilo of coffee as payment. Kills two birds with one stone then, you get your controllable roaster and we get another CS member. Win all round.... ;D

      Cheers gc ,
      Mal.

      Comment


      • #4
        Re: Crazy Popper Mod Question

        In my opinion it wont work for another reason.

        Crazy Poppers tend to run hot.
        So to increase roast times you need to get more cool air into them.
        Merely splitting the fan from the heater wont do anything because you arent going to increase fan speed too much before youll probably overwork it to death.
        And slowing it down is not what you want to do at all.
        So perceived control over the fan in reality is in my opinion worthless.

        Also, increased fan speed would blow the beans out of the popper.
        Mine has a custom fitted exhaust pipe and it lost the occasional bean with the standard fan.

        Back to what you need to control.
        As I said, you need more cool air OR you need to be able to adjust the heat DOWN.

        I managed to get 15 minute roasts by increasing airflow.

        If you look closely under the Crazy Popper youll see that half of the air vents are baffled, thereby restricting the airflow.

        To get my 15 minute roast I ended up taking the airflow idea to its extreme.

        I removed the bottom vent altogether as additional holes wasnt enough.
        I recommend adding back some plastic fly screen mesh to keep any stray chaff out.

        The big difference in the end though came from removing the top half of the poppers body.
        Youll see some screw hole plugs around the edge at the top of the popper.
        Prise or drill these out to access the screws.
        By removing the top half you are introducing thermal inefficiency and letting a lot of heat escape that previously was trapped inside the popper.
        When popping corn Im sure its a good thing.
        When trying to slow down a bean roast its not.

        When youve gone this far you can then measure your chimney because the roasting chamber is larger in diameter than the hole in the top of the popper.

        If you want to keep it looking prettier then you could try what I didnt get around to and cut out large sections of the top half of the body.
        This will let out the heat and you can screw the top back on.
        Mesh again could keep out stray chaff and give the popper a more finished look.
        Id recommend metal mesh here though.

        The above works without having to play with 240v.

        Comment


        • #5
          Re: Crazy Popper Mod Question

          Well, Ive never modded a Crazy Popper but imagine that theyre not that different to most. One of my poppers is more than 4 years old now and still gets used for small sample roasts. Running the fan slightly above nominal rpm, 10-15% over, realises quite a significant increase in airflow that so far, has not been detrimental to the longevity of the fan/motor but adds significantly to the controllability of the roast process. This is with Mistral and Tiffany poppers but surely not that different to a Crazy Popper in design.

          All comes down to how much work you actually want to do on these things I guess, considering how much (little) you get out of them. Much prefer to spend my time playing around with the Corretto and thereafter realise 1000% increase in controllability and 5-10 times the batch capacity. No contest really but I realise that everyone has to start somewhere and a popper is a good way to learn the ropes .

          Cheers,
          Mal.

          Comment


          • #6
            Re: Crazy Popper Mod Question

            Originally posted by Mal link=1205452241/0#2 date=1205478951
            The actual circuit in most poppers Ive converted to roasters has the heating element set up as a Voltage Divider, i.e. there isnt a "dropping resistor" as such for the fan power supply, rather the voltage drop across a section of the element is used to power the fan. The two sections of the heating element are actually in series to accommodate this which means you cant really separate them and thereafter achieve the same heat output as previously attained.
            Thats not exactly how the wiring was connected in the 2 poppers Ive pulled apart. The 2 heating elements were wired in parallel, not in series. There are 3 wires coming from the heating elements. 1 wire is connected to a common end of both elements, and the other 2 wires connect to the other ends of each heating element. The popper puts out plenty of heat with only the main element connected. You dont need to use the smaller, middle one at all. ie. You only need to use 2 of the 3 wires that come from the heating elements - the one that is common to both, and the one that connects to the other end of the main element. Itd be easier to explain if I could draw the circuit diagram on here....


            Originally posted by Mal link=1205452241/0#2 date=1205478951
            grab a solid state ceiling fan speed controller and feed the primary side of the fan transformer with this.
            Yep, just make sure you use a ceiling fan speed controller, NOT a light dimmer. A light dimmer doesnt work when wired through a transformer, but a ceiling fan speed controller does. They may look the same, but they obviously arnt, as I can verify as I have tried both.

            For even more control you can also wire a high power light dimmer (NOT a domestic light dimmer, as it cant handle the power - you need something that can handle 1200W) to the heating element, which is what I have done.


            regards,
            Bill

            Comment


            • #7
              Re: Crazy Popper Mod Question

              Originally posted by Mal link=1205452241/0#4 date=1205483541
              All comes down to how much work you actually want to do on these things I guess, considering how much (little) you get out of them. Much prefer to spend my time playing around with the Corretto and thereafter realise 1000% increase in controllability and 5-10 times the batch capacity. No contest really but I realise that everyone has to start somewhere and a popper is a good way to learn the ropes
              Well it depends on how much coffee you go through. My popper can roast 140gm batches, and my weekly coffee consumption is such that 2 batches in the popper produces enough roasted beans for the week.

              Also, with both the heat, and fan speed adjustable, and with a thermocouple mounted in the roasting chamber, I really doubt that a corretto setup would give any more controllability than what I currently have. But as you say, it may be a lot of trouble to go to for such a small batch size, but that really depends on what size batches you require.

              Comment


              • #8
                Re: Crazy Popper Mod Question

                Horses for courses.
                I outgrew the popper.
                A corretto will do 280g in one batch and therby save you time and effort.

                Comment


                • #9
                  Re: Crazy Popper Mod Question

                  Inspired by Thundergod I just butchered my Crazy Popper, which had been roasting way faster than typical reports here: first crack around 2:00-2:30, second anywhere from 4:00 on. Some beans have survived this to make good coffee; some have not...

                  Having removed the base and the top moulding I have pushed first crack out past 3:30 and second well after 5:00. Im hopeful that with a shorter, wider chimney and in the evening cool (its about 20C right now in Wellington) Ill be able to do better.

                  Comment


                  • #10
                    Re: Crazy Popper Mod Question

                    A 50% improvement already.

                    Do you have a fan? The extra airflow keeps the chaff away and helps both with the cool air entering from underneath and driving the heat withinin the body away.

                    The cooler evening air will also help.

                    2min to FC is VERY Crazy.

                    Comment


                    • #11
                      Re: Crazy Popper Mod Question

                      Originally posted by Bill link=1205452241/0#5 date=1205547505
                      Thats not exactly how the wiring was connected in the 2 poppers Ive pulled apart. The 2 heating elements were wired in parallel, not in series. There are 3 wires coming from the heating elements. 1 wire is connected to a common end of both elements, and the other 2 wires connect to the other ends of each heating element. The popper puts out plenty of heat with only the main element connected. You dont need to use the smaller, middle one at all. ie. You only need to use 2 of the 3 wires that come from the heating elements - the one that is common to both, and the one that connects to the other end of the main element. Itd be easier to explain if I could draw the circuit diagram on here....
                      Just goes to show how important it is to get a qualified person to do any of these mods, or certify the final result.

                      My background is in Electrical Engineering so know how to work my way through circuitry way more complex than a popper. I also knocked up several different thyristor drives for the elements of more than one popper too but in the end, found the best result was attained by winding a new element and just controlling the fan. Allowed me to roast upwards of 200g batches in summer or winter, ambient temperatures are easily compensated for and roast times of up to 15 minutes also easily accommodated.

                      For even more control you can also wire a high power light dimmer (NOT a domestic light dimmer, as it cant handle the power - you need something that can handle 1200W) to the heating element, which is what I have done.
                      You may have to go to a specialist lighting supplier for one of these as they are typically used for high power Quartz Halogen Floodlighting. Where did you get yours from Bill?

                      Also, with both the heat, and fan speed adjustable, and with a thermocouple mounted in the roasting chamber, I really doubt that a corretto setup would give any more controllability than what I currently have. But as you say, it may be a lot of trouble to go to for such a small batch size, but that really depends on what size batches you require.
                      Well Ive tried both methods (and others) now after using poppers for several years and I MUCH prefer the degree of control I enjoy with the Corretto, not just the larger batch sizes. The resulting quality of the roasts is better too and very comparable to roasts in a commercial roaster by someone who knows what theyre doing..... No contest in my opinion,

                      Mal.

                      Comment


                      • #12
                        Re: Crazy Popper Mod Question

                        Originally posted by Thundergod link=1205452241/0#9 date=1205562723
                        A 50% improvement already.

                        Do you have a fan? The extra airflow keeps the chaff away and helps both with the cool air entering from underneath and driving the heat withinin the body away.

                        The cooler evening air will also help.

                        2min to FC is VERY Crazy.
                        No, no fan. May try that when its still, but its a rare day here when there isnt a stiff breeze outside.

                        Yes, it is crazy. There are two problems, I think. First, when I got my popper, I hadnt done any background reading, so I deliberately chose the one with the highest wattage rating, thinking more was better. In hindsight that wasnt very smart, and I know $35 isnt much of a sunk cost, but still... Second, I think there is some random variation in manufacturing, and in local voltage, and between those two things I have way too much grunt in the popper department.

                        Anyway, I just tried again, with a wider tin for a chimney - the outside temp is now around 17C - and first crack didnt come on until four minutes, and I took it until nearly 8 minutes. I think I could do better too, because this roast was 100g of beans, and probably fewer beans would go more slowly. And its a warm day, as the winter comes on no doubt roasting times will lengthen.

                        Its a conundrum. I got a popper after a workmate persuaded me it was a good idea. I am almost tempted to move on and up to a heatgun-based setup - but I feel I want to see what I can do with the popper first. Get my $35 out of it...

                        Comment


                        • #13
                          Re: Crazy Popper Mod Question

                          I used my Crazy Popper for 27 roasts and spent a lot of money on it.
                          SS muffler customised to fit as chimney.
                          Flame decals.

                          I learned a lot from using it.
                          I know one famous commercial roaster that started with a popper.

                          Youll know when youre ready to move on.

                          Comment


                          • #14
                            Re: Crazy Popper Mod Question

                            Originally posted by Mal link=1205452241/0#10 date=1205569446
                            For even more control you can also wire a high power light dimmer (NOT a domestic light dimmer, as it cant handle the power - you need something that can handle 1200W) to the heating element, which is what I have done.
                            You may have to go to a specialist lighting supplier for one of these as they are typically used for high power Quartz Halogen Floodlighting. Where did you get yours from Bill?
                            I bought one from a UK online electronics place. I got the 2000W one from here: http://www.quasarelectronics.com/ci0013.htm - £16.98 + £9.95 shipping
                            It works great. I work to a spreadsheet which shows my target temp profile for every 15sec interval. With practice I know approximately how much heat I need to apply at each stage of the roast to follow my target profile, however if the thermocouple reading shows it deviating slightly off the expected path I can just nudge the dimmer control up or down slightly to compensate. Ive done roasts up to 17mins duration so far, but I could go much longer if I really wanted to. It really gives me virtually unlimited control - well I could add a PID as well for more hands free control, and this is something I may consider in the future, but its working well for me as is for the moment.

                            Batches are relatively small, however this can actually be an advantage in some situations, like when experimenting with various roast profiles. You can roast a number of small batches to different profiles to see which works best, without wasting a lot of coffee in the process.

                            Later on I may want to move on to something that can roast larger batches though, and I quite like the idea of building a fluid-bed roaster, but the popper suits my needs for the time being.


                            regards,
                            Bill

                            Comment


                            • #15
                              Re: Crazy Popper Mod Question

                              Some time ago, I stripped my Crazy Popper down as far as its possible to go and drew a circuit diagram of what I found. (and took a fair few photos for the record) The aim of this exercise was to modify the popper to gain more control over the roast profile.
                              Mal is correct in that the elements are in series in my crazy popper, with the active going to the end of the large outer element and the neutral going to the end of the small inner element. The feed to the fan motor is taken from the point where the large and small elements meet with the other end being the neutral. ie. the fan motor is fed by the voltage across the smaller inner element via a bridge rectifier on the PC board.
                              The active feed to the large element is through a 227deg thermal cutout.
                              The fan motor was marked as 24v and I measured the voltage across it when running at 14.7v.
                              After I split the fan motor from the popper AC supply, I measured the motor resistance and calculated that at 24v, the motor would draw 2.25amps and this was confirmed when measured in practice.
                              If you want to run the fan motor up to its maximum voltage from a separate DC supply then a transformer rated at 3amps or more is required.
                              I would like to add that unless you have electrical knowledge or qualifications then its best to leave any modifications to the popper supply to someone who is qualified.

                              Comment

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