I was reading a bachelor's thesis and it mentioned some technical details of a heated plate.

Part of the technical details:

MK2b Dual Power Technical Details [7]
 Power Input: 12V or 24v
 Copper boardd holes
 Resistance between 1.0-1.2 Ω (12V) or 3-3.4Ω (24V)
 EPCOS 100k thermistor hole
 Functioning current PLA 8-9A, ABS 10-12A

[Accurate quotation above - typos are in the original]

The thesis I have is called : Bachelor_Thesis_3D_Printer_Electronics_Design.pdf

The details are on page 18.

Did he make a mistake with the Functioning current?

From my very little knowledge in electronics, based on Ohm's law the current for 12V input is 10-12A and for 24V is 7.05-8A. And it doesn't matter what material is used PLA or ABS.

Or am I not calculating it properly?

  • 1
    \$\begingroup\$ You should link to a product datasheet or the page listing the technical details you've provided. \$\endgroup\$ – LMS May 26 '18 at 21:13
  • \$\begingroup\$ So, based on what you quote, the material for 24V is PLA and for 12V is ABS \$\endgroup\$ – Solar Mike May 26 '18 at 21:19
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    \$\begingroup\$ upcommons.upc.edu/bitstream/handle/2099.1/24670/… \$\endgroup\$ – johnger May 26 '18 at 22:11
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    \$\begingroup\$ I added the name of the file I have. johnger posted the link. \$\endgroup\$ – user3196144 May 26 '18 at 22:59

Going by the information you provided, it appears that the 12V resistance applies to the ABS material: 12V/1.0 Ω = 12 amps and 12V/1.2 Ω = 10 amps which is exactly as quoted. For the 24v material, assumed to be PLA, the currents calculate out to 24/3 = 8 amps and 24/3.4 = 7.06 amps. This is a small discrepancy from the quoted 8 and 9 amps. However, there is no need to doubt Ohm's law. In many cases of this nature, the quoted voltages and currents are meant to be nominal and often won't exactly conform to Ohm's law. You should consult the data sheet for the product to see under what conditions these numbers are specified.

  • \$\begingroup\$ could be about the temperatures and pwm duty cycle ? 260ºC for ABS drawing 10A-12A and 210ºC drawing 8-9A adjusted from duty ? i think duty gets adjusted depending on thermistor \$\endgroup\$ – johnger May 26 '18 at 22:10

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