Half a croissant, on a plate, with a sign in front of it saying '50c'
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wireless electric blanket

wireless electric blanket
 
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Not sure if this was previously submitted.

Why not a blanket with just one wire (standard 110V plug-in) to work like this:

Simple chip embedded in the blanket, and two (R/L) bluetooth controls

The controls would be used set the side heated and the heat settings which transmit to the blanket chip

Blanket chip would send Side and Heat settings to the blanket

I can't see anything but 110V for the blanket because battery life would be too short.

Jabert78, Jan 22 2011

Truly wireless heating http://www.fda.gov/...uides/ucm071626.htm
[mouseposture, Jan 22 2011, last modified Jan 25 2015]

Ahem... http://www.halfbake...0Electric_20Blanket
[21 Quest, Jan 22 2011]

[link]






       The thing is, it's a bit inefficient to heat the blanket itself, especially since the elements are insulated from the sleeper by the inner layer of the blanket.   

       The human body has a resistance of a few tens of kOhms (depending on lots of things). If you wanted 50W of heating (adequate, considering a wasteful electric blanket is 100W), then passing 700V between the hands (or, for more uniform heating, maybe from feet to hands) would be much more efficient.   

       You probably want DC, to avoid twitching.
MaxwellBuchanan, Jan 22 2011
  

       //to avoid twitching// and fibrillation.
[MB] I see you're proposing a constant-voltage source. It'll only be DC if the resistance is constant. Notoriously difficult to control the impedance at the electrode-tissue interface with surface electrodes. So I recommend needle electrodes, that penetrate half a millimeter or so below the skin. Lots of them, because, being pointy, they have, individually, a bit of a high impedance themselves.
  

       I picture something resembling an electrified bed of nails.
mouseposture, Jan 22 2011
  

       I think you could cope with a variable skin resistance - the driver electronics could modulate the voltage accordingly.   

       Alternatively, you could use an extremely high-frequency current which, I think, travels preferentially on the surface of a conductor. This would generate the heat where we are most accustomed to feeling it.
MaxwellBuchanan, Jan 22 2011
  

       //the driver electronics could modulate the voltage accordingly// Yes, that's a constant- *current* source (not to be confused with currant sauce). With that arrangement, you couldn't control exactly where the heat actually went (but, with surface electrodes, I'm pretty sure most of it would be at the point of contact between electrode & skin, causing burns).   

       The high frequency idea is interesting, and, in fact, maybe baked <link>
mouseposture, Jan 22 2011
  

       //Yes, that's a constant- *current* source//   

       No, we'd want a constant *power* source (which is just as easy to make).
MaxwellBuchanan, Jan 22 2011
  
      
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