View Full Version : What Sensor?

02-24-2009, 06:06 PM
I'm new at this, but I am trying to figure out a way to make a coaster (that you set drinks on) and when you set a drink on it, it lights up. So my question is, what sensor is a cheap way to make this work?

02-24-2009, 07:11 PM
Springs and switches. No microcontroller or sensor required.

02-24-2009, 08:56 PM
I think this might help. http://www.dealextreme.com/details.dx/sku.12895 It is a flat momentary switch for a airsoft flash lights. It is a little expensive but it shows the general idea. :) Jes1510 was right to it wouldn't require a microcontroller!

02-24-2009, 09:19 PM
Yup. Even simpler:

Two pieces of balsa wood cut to shape. Raised foil on the bottom piece, flush foil on the underside of the top piece. Compression springs at the four "corners" - (obviously, if it's round there's no corners, but you get the idea)

The foil becomes the two contacts of a switch. Run wire off, switch a battery and the appropriate resistor into circuit with an LED - boom. Done. Next project. ;)

It sounds more complicated than it is - you can whip this out in a few minutes.