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


  1. 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.

  2. 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?

  3. 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!

  4. 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?

  5. 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.

Comments are closed.