Smart coasters detect hot or cold beverages, created by Evil Mad Scientist Laboratories

Our friends at Evil Mad Scientist Laboratories contributed several projects to the wonderful The Hungry Scientist Handbook: Electric Birthday Cakes, Edible Origami, and Other DIY Projects for Techies, Tinkerers, and Foodies. Here's their Smart Coaster project.

Smart Coasters are cast-plastic coasters for your drink that light up red when you put a hot drink on top and light up blue with a cold drink. The design is fully analog-- no microcontrollers and no programming-- and they incorporate a solar cell so that the whole thing is hermetically sealed: waterproof and washable. Complete step-by-step DIY instructions are included for both the electronics and the resin casting.

Mark Frauenfelder is the founder of Boing Boing and the editor-in-chief of MAKE and Cool Tools. Twitter: @frauenfelder. Come and hear Mark speak at the ALA conference in Chicago on July 1.

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Now, for some real fun, take the same basic circuit, but hook up some of those solid-state ceramic heating/cooling tiles, so that it heats hot drinks and cools cool drinks, automatically.
Buckethead

At last, a coaster for those of us who cannot perceive temperature!
MrSquirrel

Coasters that detect hot and cold drinks. What a wonderful new technological breakthrough! Aren’t we fortunate to live in such times?

Only one question: Why?
jesushootscores

Perfect to take along on those long flights!
morcheeba

I love Windell’s use of analog circuits when other people would first try digital. This stands out in their awesome LED coffee table.

A simpler (digital) route would be to configure two DS1821‘s (one for each LED), but they are $2.20 each. And that circuit wouldn’t look or act nearly as cool as the analog one!
Jerril

With regard to “Why” – why do you put pictures on coasters? It’s interesting to look at, offers a few moments of amusement, and has blinkenlights on it. Why not?
Mitch

At first I scoffed, but now I realize that
the beauty in this lies in it’s uselessness.

It’s still a neat little gadget.