How do espresso machines sense stuff?

Aug 14, 2010 3 Replies

Just got one of those machines, you know, you put in beans and add water and press a button, it grinds, tamps, infuses and brews espresso automatically.



What I'm wondering about (before taking the thing apart, I hesitate!) is how can it



1) Sense if it's out of beans?
2) Sense that the grinds basket is full?
3) Sense the water?

In all cases I suppose it can weigh things, but I don't think that's how it works.



It can sense if the grinds basket is removed, but I can hear what I assume to be a microswitch clicking.



I've looked as much as I can at the thing and I don't get it. There are no obvious holes or pokey bits sticking out.



It's a Saeco Vienna Superautomatica.



And yes, I know how the boiler temperature sensor works.


Infrared sensors probably. Look it over with a digital camera. The IR beams should show up in Green.

Huh?

940 and 950 nm IR LEDs show as magenta on two different (Canon & Nikon) cams here, but I don't have any closer to red LEDs here to try.

Curiosity :)

Grant.

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