Tag: MOSFET

Arduino Power Controller for Prusa 3D Printer – Auto Shutdown

In this video I run through the design and build of an add-on for my DIY Prusa i3 MK2 3D Printer that controls the supply of power to the printer’s two power supplies.

I wanted to add this for two reasons. Firstly I wanted an extra layer of security in case any of the electrical components failed in a catastrophic way leading to over heats, particularly the power supplies as I doubt their quality based on the budget prices. Secondly I wanted to be able to add G code (M Code actually) to my prints so that once the print it finished the printer is shutdown, including the power supplies.

More details in the video, but as discussed here is the schematic:

Arduino Power Control Schematic

Arduino Power Control Schematic

I also mention that I am now using Sublime Text instead of the Arduino IDE. I use Sublime Text on a daily basis and it has a lot more editing features than the IDE. When I found this brilliant add-on package for Sublime Text, called Stino, that brings Arduino syntax highlighting, compiling and uploading directly from within ST, I switched instantly. Even if you don’t already use Sublime Text – it might be worth it just for this!

Finally, if you really want to you can download my source code for the project – as it stands at this point. As explained in the video it is very much an evolution from a basic idea – so isn’t that well written. But it does the job.

Prusa i3 MK2 3D Printer – Electronics Mounted, FINALLY!

In this video I show how I ended up mounting all the electronics for the Prusa i3 MK2 clone. As the frame wasn’t as solid as the original’s aluminium one I decided that it needed a brace, which provided the perfect location to mount the Arduino, RAMPS, Raspberry Pi and all supporting parts.

I also added a brace to the other side – which gives me room for electrical expansion!!!!

I mounted the whole thing to an office desk, I picked up for free, and even though all four corners of the Y axis are square and sit on the desk, there is a slight amount of hammering when printing.

To silence that I drew up and printed out some little securing clamps which just make sure they cannot move. You can click the image below to download the STL for these clamps. They should work on any printer using the same Y Axis design and the Prusa i3 MK2.

Prusa i3 MK2 Y Axis Securing Clamps

Prusa i3 MK2 Y Axis Securing Clamps

And just in case anyone might find it useful, here is the STL for my RepRap Discount Full Graphic Smart Controller mounting plate, which is just a plate with mount holes in the right places and a boss on the rear tapered to accept the nozzle of a flexible cooling hose!!!

RepRapDiscount Full Graphic Smart Controller Mount

RepRapDiscount Full Graphic Smart Controller Mount

 

Prusa i3 MK2 3D Printer – Electrical Upgrades/Mods – RAMPS & Arduino

Continuing with my mission this week to actually finish the electrics on my DIY Prusa i3 MK2 3D Printer, in this video I make some modifications to the RAMPS board and the Arduino.

On the RAMPS I need to remove the 4 pin power connector. Now that the RAMPS board is not carrying the current to the heated bed it isn’t really a safety issue (although it might be if yours is carrying heated bed power…) but it just simply takes up too much space for how I want to mount it. And a soldered connection is more reliable that a connector, well usually!

I am also junking the polyfuses. Again not so much a safety issue now as there is only a little current going through them, but even so the 5 Amp one still feeds everything apart from the heated bed so they have to go. Replacing them with a simple blade fuse holder and fuses – you know,  like off of cars n stuff 🙂

In the last video I created a separate MOSFET board to handle power to the heated bed. The gate of the MOSFET is driven high by pin D8 of the Arduino, so I also add a signal wire from D8 that can then attach to my off-board MOSFET.

Lastly, I remove the DC jack on the Arduino. It isn’t being used or causing any issues, but I just don’t like it… well no, it got in the way of my board mounts.

That just leaves fixing the corrupted garbage that appears on the LCD after a couple of minutes. After quite a lot of time spent (more than quite a lot..), I have fixed it. That will be the subject of my next video.

Prusa i3 MK2 Clone – Electronics – 24V Heated Bed Upgrade

I have changed my mind a few times about how I plan to finish off my Prusa i3 MK2 clone 3D printer… but now I have settled on a plan! None of it was particularly complicated, but I just want to arrange things in such a way that they are safe, tidy and give me the best result.

As I plan to add a physical brace to the Z Axis frame, I want to combine that with a suitable housing for all the electronics. With the actual brace made I can start finishing off the electronics!!!

There are few items I want to do:-

  • Fix the issues with LCD corruption – presumably cause by electrical noise
  • Remove the Polyfuses and provide alternative
  • Integrate the Raspberry Pi in with the other electronics so it is a permanent feature on the printer, including power
  • Add in additional temp sensors to the electronics and power supplies that will kill the power if anything looks dodgy
  • Power the Heated Bed with 24V instead of 12V – but keep this 24V separate from the RAMPS board

The last of these is the item I am doing first – and it the subject of this video.

The links I discuss in the video are:

Below is my rough schematic showing how I will wire the RAMPS, Arduino and also a small external board that will perform the heated bed power switching. Beneath that the calculations I made to conclude that the AUIRFB8409 Mosfet would work fine:

Rough Schematic of an external board to switch power to the 24V heated bed, showing relevant parts of the RAMPS and Arduino

 

Main considerations in choosing the AUIRFB8049 Mosfet, with calculations

© 2023 Jules Gilson

 

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