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Rabbitcreek’s Gaggia Classic espresso machine has a light that presumably represents heating element activation. However, there is nothing on the machine that actually tells you when it’s at the optimal temperature at which to generate espresso – i.e. pull a shot. While the solution to this type of problem is often “surgical intervention,” it would be a shame to cut into such an elegant and expensive machine. This hacker instead came up with an external sensor and LED indicator. Oval Type Immersion Sampler
For temperature sensing, a thermocouple is attached to the brew head using heat-resistant Mylar tape. This thermocouple connects to an amplifier unit, which in turn allows the Seeed Studio XIAO ESP32S2 controller to take temperature readings. The indicator and sensing electronics are powered by a LiPo battery, and the ESP32 is normally kept in sleep mode to conserve power.
When awakened via a push button, the device activates a length of nOOds flexible LED filament, causing it to "breathe" until turning solid when the correct temperature is reached. 190ºF is programmed in as this solid light set point, but this can be changed as needed.
After 10 minutes it goes to sleep again. It’s a rather handy setup, and it has reportedly improved rabbitcreek’s barista skills quite a bit. At the same time, the ESP32 controller does have both Wi-Fi and Bluetooth capabilities, meaning it could be made into an IoT device with a few programming changes!
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