Instructables

A fully automatic coffee bean roaster (Arduino)

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Step 5: Testing..... and roasting your coffee beans

Ok, so now you connect the popcorn machine to the Arduino, to the 19V and 220V power supply and you connect the Arduino to the LCD screen and your computer, and you are ready to test your roaster.

I guess if you use the program, the temperature sensor should be more or less ok. But better be to calibrate is, and if necessary to adjust is. For this you would need a thermometer which can measure up to 220C. Measure at difference temperatures and adjust  "a = 0.6271 and b = -213.13"

Next I suggest to try out some things, see how it works and follow the temperature profile with the front-end program. You will need some beans to be able to follow the temperature profile. Take good care that you set a minimal fanspeed that still keeps the beans a little bit moving. Otherwise the beans might burn (can work out dangerously!). As the roasting progresses, the beans get lighter and therefore the minimal fanspeed can be lowered.

If this all works out, I suggest you try your first batch of coffee beans. Mine can take up to 100g of beans each time, which isn't so much (but then I dont drink THAT much coffee). If it works out fine, you can start to experiment with different profiles (I would suggest to start with the final temperature settings)

Good luck and enjoy.



I have thought about an additional controller that would keep an eye on the beans. If they stop dancing then the fan speed should be increased a little bit. Couldn't think of any way to sense this, so if you have any suggestion please let me know.
 
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If the beans lift up a bit, you could set up what is known as a 'reed switch'. Two thin strips of metal, say Stainless steel, 1/16th apart. As the beans lift up they close the switch. That would make the logic easy. Or even bump it over and over, as long as it is closing and opening the controller would know that they were moving.

To add function, mount it on a threaded rod so you can tune the level easily.

This is the method used in polyethylene plants to measure the level in holding tanks. Poly is made as small pellets, shaped like a coffee bean but smaller. Of course they don't move around, just fill or drain.
Adam Manick4 years ago
Maybe use a sensitive vibration detector. you can even make one.
tilas754 years ago
How about a piezoelectric sensor?
Maybe a webcam, and some optical recognition software.  That sounds really complicated, but probably the best bet.
dkelly19664 years ago

A microphone could not only tell if the beans were moving but could also tell when they crack :)