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Coffee Roaster Modifications to Air Popper

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  • Stoney
    replied
    Thermocouples arrived today so made a logging device that dumps the data to an MQTT server every 5 seconds, then pulled the data and plotted it. time scale in minutes
    This was my first test run with the 4 seconds on, 6 seconds off technique on the el cheapo target popper and it seems quite reasonable from a quick web search.
    Attached Files

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  • Jackster
    replied
    After reading the 2008 thread, i see this has been going on for some time.
    I might have to get one of these poppers yet.
    Inspiring stuff!

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  • Jackster
    replied
    Both of you have done great work that is beyond my skills. Awesome jobs!
    Who would have thought a pid popper....

    I did find some small hard drive transformers. Good for 2a at each of 5v and 12v. Pretty handy to run 5v sensors, and 12v computer fans...they were on ebay for few dollars.

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  • Stoney
    replied
    I did some experiments with a thermocouple in the beans and a PID controller which ends up cycling power on for 4 seconds and off for about 6 seconds, so being lazy decided the temp control is not that important so long as it does not go crazy at the beginning. Found that with PID control with no ramp I still needed to bring the temperature up in a few stages anyway.
    So with all that in mind I made a little triac controller with a PIC10F220 that simply turns the power on for 4 seconds, off for 6. I can add temp control etc later or a cutoff timer but for my needs suspect it is not required.
    Takes around 9:30 for a medium roast and 12:30 before second crack.

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  • Stoney
    replied
    pulled my target popper to bits today and noticed it is using the heating element as a big voltage divider for the fan, which pretty much sucks as like you found you need a 24v supply, I put it vack together while I think about it some more, forgot to measure motor current, any idea what the fan needs ?
    Going by the resistance I thoght they were over volting the fan quite a bit, 47R total and 7R for the fan portion, about 1:7 divider which puts it at around 37.4v rms to the full wave rectifier, but you multiply that by 2/pi (0.636) and end up with 23.8v for the motor ignoring diode drops and motor current across the heater.
    Considered being lazy and just chopping the power but its going to lower the fan speed as well and end up with much the same temperature.
    So I will probably end up going much the same route as you, perhaps use an esp32 or esp8266 to give me a wifi enabled version.

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  • Deurgo
    replied
    And lastly my latest addition to my setup. I wired and programmed an Arduino Nano with a max6675 board to monitor temp in artisan. Long long process but I did it with the help of countless forums and determination. The end result? First couple of roasts looked like this. Click image for larger version

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    First one is halfway through a PNG with a lot of learning as you can tell. Second is Swiss water decaf that didn’t turn out too bad!! Either way I’m stoked. Just wanted to share my joy!

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  • Deurgo
    replied
    A bit late on the update on the roasting. I did do a batch the following night after completing the project and it worked a treat!! managed to drag the roast time for 3.5 to 4 mins - 12-14 minutes!! Was super happy with it and can't wait to get a temperature logging setup so I can mimic the roast on my Coretto roaster which I am currently in the midst of building as well. Thanks for your help guys!
    Click image for larger version

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  • Dimal
    replied
    Nicely done mate...
    All safety certified by your Electrician friend I hope...

    Mal.

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  • Deurgo
    replied
    G'day guys. Update for you. I've met with a great guy from my local town and together we've put together the below. The digital display down the bottom is for the % of speed the fan motor is running at. the two knobs are varying points for the fan and the heater and then switches just isolate the fan or the motor. Anyway test run tomorrow night so will let you know how we go! Thanks for the suggestions.

    So I went with a PWM and an SCR controller for the fan and heating coil and both work amazingly well - plus a 24vDC power supply that my local guru built for me. Amazing venture and super excited for it's maiden voyage tomorrow.

    https://photos.app.goo.gl/yTvkhjf7GQegTWXZ2
    https://photos.app.goo.gl/insm7WenNy67ZeEm2

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  • Deurgo
    replied
    Thank you for your advice. I have a few friends who are electricians. So before anything is plugged in or turned on I’ll be getting them to check everything out or maybe wire it up for me. This is more of a project to enjoy and I have no intention of putting myself in harms way. Thank you for your advice and concern! I’ll let you know how I go �� quick question again, wiring the complimentary up to a few switches. Any recommendations on how to go about this?

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  • Dimal
    replied
    I agree Yelta...

    Mal.

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  • Yelta
    replied
    I know the electrical advice is well meant, however would suggest unless your a qualified electrician you leave this type of modification to the experts.

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  • deegee
    replied
    I have done this with Black & Decker, and Tempo poppers which were easy to work on, but they died or were given away.
    Sorry but I didn't take pics during construction, and my current unit is based on a Breville, which is a real PITA to dismantle.
    But all that any pics would show is the motor with no board, and a bunch of wires.

    On most of the poppers I have seen, the PCB is soldered diectly onto the motor terminals.

    To split the fan off, I un-soldered the PCB from the motor and removed it. This is a neat simple job, but did require rejoining the neutral wires and capping the low voltage active that originally powered the fan.
    With most of these units, it was easy to remove the board from the motor, connect the output from the DC power pack via the pot to the motor, and the output from the SCR to the coils, so that's how I did it.


    If the design of the Sunbeam makes this method difficult, maybe you should have a look at post #22 in this thread :- http://coffeesnobs.com.au/roasters/2...-question.html

    Cheers, deegee.

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  • Deurgo
    replied
    Thanks deegee - from your experience, how do I go about wiring them up though? Do I need to remove the board that the dc motor and all the wiring goes to to power them separately? Could you show me some photos of yours?? Inside if that’s okay

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  • deegee
    replied
    Have a look at this :- http://coffeesnobs.com.au/home-roast...icks-mods.html

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