Hourglass LED Lamp

Discussion in 'General Electronics Chat' started by Metalmann, Aug 18, 2014.

  1. Metalmann

    Thread Starter Active Member

    Dec 8, 2012
  2. Sensacell

    Senior Member

    Jun 19, 2012
    I bet it's just a design concept at this point. Enough sand to actually power the lamp would render the thing big fat and ugly.
  3. tom_s


    Jun 27, 2014
    great idea

    depending on how long it took the sand to get from top to bottom. i would assume some waterwheel type device in the middle running a small magnet past a coil to feed the LED.
  4. wayneh


    Sep 9, 2010
    One kg of sand falling through 0.02m (2cm) provides 0.2J of potential energy. Spread over 5 minutes, that's 0.67mW and not enough to light the LED as shown. I suspect a battery is present. Note that the total drop of the sand is irrelevant - all that matters is how far it falls within the mechanism. I can't see how it could be much more than an inch or so and still fit inside.

    If it's not a hoax, I'm thinking it uses an axial rotation, parallel to sand flow, instead of a water wheel axis perpendicular to flow. I can't see how it could work without a mechanical conversion, unless there is something special about the "sand".
  5. Sensacell

    Senior Member

    Jun 19, 2012
    A fluidic solution would be better, I don't think sand can create the kind of pressure difference that would help the situation, too much friction between sand grains.

    Industrial design students should be taught more physics, it's so common to see ideas like this that seem clever from a distance, but are not viable in the real world. The second sad thing is that most people automatically believe in any new 'technology solution' - for the same reason, poor science education.