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thanks Tamarian,

The module linked (thanks JackH) is like a line of photo interrupters, it should be easy enough to look for blocked light (floating beans) above clear air, eg:

x
x

x

x

x
x
x
x
x
x
x

where x's are light readings.

Probably pick on up soon, working on the auto doaser for my grinder atm using a load cell.

best regards

Lee