Basics about switching loads (hotend, heatbed) with MOSFETs

Hi !

Very often users have problems with the MOSFETs used for switching heatbed and hotends.
I wrote an article to understand the basics.

Basics about switching loads with MOSFETs

Edited 3 time(s). Last edit at 05/03/2013 01:05PM by STB.

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Grüße / Regards

STB

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Basics about MOSFETs

Excellent article, STB!

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Generation 7 Electronics	Teacup Firmware	RepRap DIY

Thanks!

I thought the proper term was Shunt Diode.

Used on relays too to dump the magnetic collapse from back feeding through an output on a microcontroller.

The RAMPS 1.4 does have an LED in parallel with the output load. Does that help shunt the back feeding?

Not really, as the LED is forward biased rather than reverse biased.

Cefiar Wrote:
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> Not really, as the LED is forward biased rather
> than reverse biased.

Ahhh, good point.

Inductive load for FET is not that bad. The FET operates in avalanche mode, same FETs are rated for this.
(some info here: [www.irf.com], Googling may get better results)

ShadowRam Wrote:
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> I thought the proper term was Shunt Diode.
>
> Used on relays too to dump the magnetic collapse
> from back feeding through an output on a
> microcontroller.
>
> The RAMPS 1.4 does have an LED in parallel with
> the output load. Does that help shunt the back
> feeding?

There are several names for that component

[en.wikipedia.org]

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Grüße / Regards

STB

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Basics about MOSFETs