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7760Re: PCB as heated build bed

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  • R J Hamlett
    Dec 6, 2012
      On 06/12/2012 16:11, diy_3d_printing_and_fabrication@yahoogroups.com wrote:
      > Hi Graham
      > The Peltier device is not a pump, it is a Low voltage solid state heater or
      > a cooler simply by changing the polarity. The Copper, Brass or aluminium
      > build platform is the attached heat sink.
      > The 12VDC supply is switched on or off by open circuiting the yellow and
      > grey leads on the computer power supply via the relay on the temperature
      > controller. All at low voltage except for the mains powered temperature
      > controller that is designed for purpose.
      > Simples !
      No, Graham is completely right.
      The Peltier device is a thermoelectic heat pump. Used as a heater, you
      need a heatsink to harvest heat as he says. It is not as bad used as a
      heater, as when used as a cooler. For the latter, you need a heatsink to
      dissipate both the heat being pumped, and the heat generated by the unit
      itself. Going the other way as a heater, quite a bit of the heat comes
      from the inefficiency of the device itself.

      Best Wishes
      > On 5 December 2012 21:05, Graham Stabler<grezmos@...> wrote:
      >> **
      >> Don't forget that you also need a big heat sink to efficiently harvest
      >> heat from the surroundings as it is just a pump.
      >> A 250w cartridge heater is 2 quid on eBay and a good alternative to the
      >> slightly costly silicone pads.
      >> These could be used with the same controller but it might be wise to go
      >> with a totally low voltage system unless you know what you are doing.
      >> To return to the original poster, a number of people have just used some
      >> nichrome wire and taped it to the underside of the bed with kapton tape,
      >> I've even seen a few people use power resistors screwed underneath.
      >> Graham
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