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PWM, MOS, and the propeller as a heated bed regulator — Parallax Forums

PWM, MOS, and the propeller as a heated bed regulator

max72max72 Posts: 1,155
edited 2011-08-04 03:47 in General Discussion
I'm investigating the possibility to build a heated bed for the 3D printer.
I'm intrigued by the PCBs with Al substrate.
So my idea is to use the tracks to heat the PCB, add a PT1000 or similar sensor, and control the current on the PCB tracks with the Propeller, and the IRF3708 Mosfets.
I would like to know if I can control the heating using PWM with the Propeller.
It could be possible to have more than 1 heating circuit controlled by independent MOS. Would this approach be preferable? This way I could have a part of the heating circuit ON all the time, and control only a part with the PWM.

Thanks in advance,
Massimo

Comments

  • Cluso99Cluso99 Posts: 18,069
    edited 2011-08-04 03:16
    Yes you can. It is all to do with the tracks and their resistance as you lay them out. See the RepRap forums as there are examples of pcbs there.

    You may require a high power low value series resistor to set some sort of current limit. If you do, make sure you can also use the heat from it too.

    I haven't checked your Mosfet.
  • max72max72 Posts: 1,155
    edited 2011-08-04 03:47
    Thanks.
    In fact I got inspired by the various solutions available on the Rep Rap forum. There are nice track resistance calculators available on the net.
    I was also considering some sort of thermal switch as a safety measure. Could it work?
    Massimo
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