A fully automatic coffee bean roaster

I  made from an ordinary popcorn machine. In basic it works by a fan blowing air past a heating element through the green coffee beans. By controlling the fan speed, I was able to control the temperature of the air roasting the beans. But, the roasting process turned out to be quite hands on, as the temperature needed to be kept constant following a profile, which was done by measuring the temperature the whole time and adjusting the fan speed with a pot meter.

Source: nightlife31


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