FloatShield: The next one (R2->R3)

[PeterChmurciak]

@gergelytakacs @erik1392 Personally I am very dissatisfied with how the things have ended up on the FloatShield R2. Despite our best efforts, the R2 version, specifically the fan that the board was built to accomodate, is not usable for our purposes. It saddens me that "my" version is not better - not really an proper upgrade, to the R1.

Therefore I propose to make another version (not really sure what to call it, whether R2 - version 2, or R3) that would bring all the compatibility changes the R2 should have brought, without using the new fan - using the original one - either canibalised or bought from store. Alternatively some other fan of this type (two-cable type) could be used, but based on our previous experience, I am not confident in experimenting with unknown fans.

I am well aware that @gergelytakacs is currently preoccupied with more important things than my "hurt ego". Because of this, and possibly to avoid the school bureaucracy, I will order the PCB and required parts by myself.

All I would like to ask for, is your (gently applied) constructive criticism 🙂

[PeterChmurciak]

@gergelytakacs @erik1392 Could you please look at the scheme and PCB layout to see if there is any mistake or whether you would like to see something done differently ?
(By no means do I want to hurry it. If there should be another version, it has to be a working one)

Original R1 scheme (for reference):

New R3 scheme:

And PCB layout for R3:

Top: (gray line represents fan dimensions)

Bottom:

[gergelytakacs]

@PeterChmurciak

First of all, good job, thank you. I'm reviewing this right now - based on this post and not the files.

Schematics:

• Looks good, I went through it quite carefully.
• I can't confirm the pin orientation of the MOSFET from the top of my head. Sleep deprived and on the train, it looks ok. Please double check it.
• The schematic symbol of the MOSFET is not very well readable. The reason is the small arrowhead, since that is the main point of orientation for Drain/Source.

PCB:

• Missing logos, etc.
• Looks good otherwise.
• I have not double checked the correspondence with the individual traces w/ the schematics, but if it was auto-generated it should be all-right. Double check it before we send it to manufacturing.
• It is a bit weird how this "fat" trace continues as a thin one:
  

@erik1392 please express your opinion as well.

[gergelytakacs]

@PeterChmurciak

Replying to your thread opener:

• Other than you, three more people (@gergelytakacs @erik1392 @mgulan ) were looking at the new version, neither of us expected these problems. We learned a lot. This is what development/science looks like. Don't beat yourself up over it.
• I can order the new PCB as soon as it is ready, don't worry about that.
• I would avoid any great changes now, since time is pressing. I may have ideas, but let's not use time for hardware revisions!

[PeterChmurciak]

@gergelytakacs

pin orientation of the MOSFET

Orientation of mosfet is (from top pin to bottom pin on picture) Gate connected through resistor to pwm pin 5, Drain connected to the fan grounding pin and Source connected to the ground. I have checked and I believe it is correct.

schematic symbol of the MOSFET

Is this symbol better ?

And PCB:
Top:

Bottom:

I have downloaded and used Helvetica Condensed font on the AutomationShield logo this time, hopefully it is the correct one.

I will check everything once more.

Please take a look again and tell me if everything is all right, or you would like to see something done differently.