Author Topic: EEVblog #974 - PCB Layout Walkthrough  (Read 9104 times)

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Online EEVblog

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EEVblog #974 - PCB Layout Walkthrough
« on: February 25, 2017, 09:10:09 pm »
Part 4 of the Nixie tube display project.
In this tutorial Dave walks you through a complete PCB design from begin to end, with a ton of hints and tips throughout that can be applied to any PCB layout package.


 
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Offline RGB255_0_0

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Re: EEVblog #974 - PCB Layout Walkthrough
« Reply #1 on: February 25, 2017, 09:15:16 pm »
74 minutes. Time to make some popcorn  :popcorn:

Nice vid, Dave. I ended up being trapped as a young player inbetween some traces. How do I get out?
« Last Edit: February 25, 2017, 10:44:55 pm by RGB255_0_0 »
Your toaster just set fire to an African child over TCP.
 

Offline Smokey

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Re: EEVblog #974 - PCB Layout Walkthrough
« Reply #2 on: February 25, 2017, 10:43:44 pm »
What a strange wonderful world.  I sat down with the intent of working on a layout, but ended up watching a video of someone else working on a layout.
 

Offline trophosphere

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Re: EEVblog #974 - PCB Layout Walkthrough
« Reply #3 on: February 25, 2017, 11:10:36 pm »
I watched the video a quarter of the way through and then, while it was still playing, started working on laying out a PCB for my own project. Hurray for multiple screens.  :)
 

Offline mariush

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Re: EEVblog #974 - PCB Layout Walkthrough
« Reply #4 on: February 25, 2017, 11:35:09 pm »
Interesting... watched it to the end.

I noticed you used LT1117 .. that's one of those regulators that needs some ESR on the output for stability, not sure that's satisfied with your ceramic capacitors. The datasheet recommends esr below 0.5 ohm .. the Linear datasheet datasheet doesn't say but other manufacturers mention at least 0.1 ohm esr

While you were routing those traces I was thinking ... you could just put those chips on a tiny vertical board with just their decoupling capacitors and basically create a SIP like module the width of the board (with a  right angle 0.1" spaced pins to connect it to the base board) . You'd get all the pins actually needed in a row nice and easy to route to the nixie tubes without going around chips, and you have plenty of vertical space anyway due to the height of the nixie tubes. Wouldn't add that much to the cost of making the board, you'd just put there an instruction to v-groove a portion of the pcb.

I was also thinking what if you placed all those chips at 45 degrees. Would have allowed for more routing room between the chips so maybe a bit nicer routing.  Yeah, would suck as you can't use straight "bus bar" style traces under all chips for the clock stuff but a couple of vias under each chip would be easy to add.

« Last Edit: February 25, 2017, 11:36:58 pm by mariush »
 

Offline Macbeth

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Re: EEVblog #974 - PCB Layout Walkthrough
« Reply #5 on: February 25, 2017, 11:36:13 pm »
Dave, have you double checked that the IN-12 footprints you "borrowed" will work with your tubes mounted on the top side of the board?

I have to admit I have played with the same "borrowed" footprints and two different public STEP designs just getting to grips with CircuitStudio and am still kind of confused about the orientation.
 

Offline Zom-B

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Re: EEVblog #974 - PCB Layout Walkthrough
« Reply #6 on: February 25, 2017, 11:48:08 pm »
Really... what's up with this forum... Thrice! I can't even post anymore?

"You already submitted this post! You might have accidentally double clicked or tried to refresh the page."

I just wanted to post this:

Quote
What's with this bloody forum?! Twice!!
"You already submitted this post! You might have accidentally double clicked or tried to refresh the page."

No it's not. Where is my post with good advice along with my complaint about another SMF bug? My actual post ended in something like this, but it's gone now:

Quote
What's with this forum bug? It complained that my image was >1Mb. Okay, fair, so I clicked back, compressed my image and tried again, then it complained that the last post from my IP was less than 60 seconds ago!

And there's my image, and because I hate typing stuff twice I'll let you figure out what It means. My conclusion and final advise was to swap the order of daisy-chaining (sending the last digit in first).

« Last Edit: February 25, 2017, 11:50:30 pm by Zom-B »
 

Offline dynorat

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Re: EEVblog #974 - PCB Layout Walkthrough
« Reply #7 on: February 26, 2017, 12:07:16 am »
great job looks really good you forgot the  bodge-wires lol nice video I watch them all thank you 
 

Online Brumby

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Re: EEVblog #974 - PCB Layout Walkthrough
« Reply #8 on: February 26, 2017, 04:06:49 am »
Interesting video.  I watched it to the end.

It's been many years since I laid out my first PCB - and I did it by hand.  Fortunately, it wasn't too complicated.  I haven't had the need to do much of this for some time - but I understood all of the issues Dave mentioned and appreciated the limitations of the software.

One thing I would have liked to have seen is the result a full autorouting would have created - and have Dave go over a few of the most dastardly decisions it made.


Still ... it kinda makes me want to dip my toes into the water.............
 

Online EEVblog

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Re: EEVblog #974 - PCB Layout Walkthrough
« Reply #9 on: February 26, 2017, 07:15:15 am »
What a strange wonderful world.  I sat down with the intent of working on a layout, but ended up watching a video of someone else working on a layout.

Isn't that how the worlds biggest Youtuber is a gamer?
People just watch him play instead of playing!
 

Online EEVblog

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Re: EEVblog #974 - PCB Layout Walkthrough
« Reply #10 on: February 26, 2017, 07:31:44 am »
Dave, have you double checked that the IN-12 footprints you "borrowed" will work with your tubes mounted on the top side of the board?

Yes.
 

Offline cheetahkid

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Re: EEVblog #974 - PCB Layout Walkthrough
« Reply #11 on: February 26, 2017, 08:53:17 am »
I may have misheard it, about the high voltage PSU. I like it to see it on the same board rather than separated. But that up to you.
 

Offline Chupacabras

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Re: EEVblog #974 - PCB Layout Walkthrough
« Reply #12 on: February 26, 2017, 09:43:01 am »
Is it possible to render that board with better quality? That 3D model for nixies looks awsome, it would be nice to see your board rendered with that quality model. (If it is possible. I do not use Altium)
 

Offline HSPalm

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Re: EEVblog #974 - PCB Layout Walkthrough
« Reply #13 on: February 26, 2017, 11:27:19 am »
Unfortunately, a step-file does not know about transparency, reflections and/or materials. The rendering in the image was done with features from the CAD package and rendered in the image export. All those fancy extras are lost when exported to .step.
 

Offline Tabs

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Re: EEVblog #974 - PCB Layout Walkthrough
« Reply #14 on: February 26, 2017, 12:43:59 pm »
Hi Dave,

Just watching this now. reached 12 mins into video ...

In case you didnt know -
use 3D mode and "Tools>3D Body Placement > Align Face with Board"

Pick the 3D body to align, then pick a face on the body to align with the board using the menus.
Switch to 2D to align centers.
 

Offline Windfall

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Re: EEVblog #974 - PCB Layout Walkthrough
« Reply #15 on: February 26, 2017, 12:49:16 pm »
Entertaining and informative (especially all the Altium tricks, I currently use Diptrace, so I certainly make do with much less ...).

But I'm sorely missing an emphasis on consistency, which I find is the essential ingredient in designing nice PCBs, even one-offs. As far as I'm concerned, making a one-off is not a great excuse for (a term often used in the video) 'mucking about'. You might be doing a whole bunch of these next, and then you'd basically have to start over. In addition, a circuit like this practically dictates consistent routing, and I'm not seeing too much of that in the end result, really. Yes, yes, 'one-off' and 'mucking about'. I still don't like it.  :(

Just my two cents.
« Last Edit: February 26, 2017, 01:05:45 pm by Windfall »
 

Offline johnmx

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Re: EEVblog #974 - PCB Layout Walkthrough
« Reply #16 on: February 26, 2017, 02:35:19 pm »
Hi Dave,

A small hint. I notice you selected several segments (of the same track) one by one to delete them all (at minute 56:49). You can just select the first and press TAB to select the rest. If you press TAB again it will select the entire net.
Best regards,
johnmx
 

Offline QuantumLogic

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Re: EEVblog #974 - PCB Layout Walkthrough
« Reply #17 on: February 26, 2017, 02:54:08 pm »
I am a brand new learner of PCB design.  I've watched other videos about PCB design but still had questions like "But am I really doing this the right way?" in terms of some of things I end up doing in KiCad but don't see mentioned by the presenter.  I thought I might have been doing things the wrong way, the stupid/ass-backwards way, etc.  But Dave's video confirmed that many of the things that I end up doing with my extremely limited experience are the same things Dave does with his many years of experience and more mature PCB design software.

Some examples of what I mean:

1. Measurement standards: Dave mentioned that he constantly switches between imperial and metric.  I do too, but attributed it to being a noob. I use metric for board size, edge cuts, holes and trace widths but I use imperial for component spacing and pin alignment.  It was nice to see that Dave validated that switching between the two measuring standards is "normal."  For some reason I thought people would stick in only metric or imperial and I was weird for constantly switching around depending on what I was doing.

2. Vias: In my current 2-layer PCB design I have no additional vias, but everything is through-hole in my design so I am able to use the component holes as a via instead where needed.  I thought vias were considered to be a "last resort" type of thing and to be generally avoided due to the additional resistance each one adds to the circuit, but Dave uses them without too much concern in this particular design.  The sheer number of traces going between components also necessitates the use of vias in his case, but it is good to know that using vias is not really too much of a negative in basic DC/low current/low frequency PCB designs.  Obviously a high frequency design would need to be concerned about many more things than just vias.

3. Optimization:  It is clear that if Dave had more time to spend on the design, he would like to perform a lot of pin swapping in order to simplify the layout.  But a person only has a certain amount of time to dedicate to the task so compromises have to be made.  It was nice for me to see, as a complete noob to PCB design and layout, that even someone like Dave, who has many years of experience, reaches his limit of time and effort before coming up with a truly elegant layout.  And he's OK with that.  It is a one-off, after all.  :)

4. Tweaking:  While you could argue that this is similar to Optimization, above, I think it deserves its own discussion because I consider optimization to be more general in terms of overall layout and reduction in rats nest crossing before any traces are laid down while tweaking is the nitty gritty individual placement and slight movement of components, tracks and vias to "make it work."   Moving a track over to allow another one next to it, moving a via from down low to higher up the board in order to allow a cross trace go through, that kind of thing.   It was nice to see Dave doing those things which are similar to what I end up doing in my layouts.  I figured that with experience comes less fiddling around, but it seems that PCB design is really an art and every board needs individual attention to detail in a unique way.  My problem is that I am such a perfectionist that I will spend too much time on something rather than just "letting it go."  Good thing I don't get paid by the hour.

5.  Software features:  While watching the video, I could completely forget that Dave was using Altium Designer.  The overall basic functionality and features that Dave was using for this layout are available in the latest stable release of KiCad (4.0.5) so I could totally relate to everything Dave was doing and follow along as if Dave were using KiCad.  As a noob, I had no idea how much additional functionality would exist in a product like Altium but would have no equivalent in KiCad.  But at least for this particular non-demanding PCB design, I think everything Dave did in Altium could be done in KiCad in a similar way.  The new OpenGL push/shove trace router in KiCad seems to be very close in functionality to Altium's router which was nice to see.  I guess my point of this is that even open source software can give someone the power to create good designs - expensive design software is not required.  At least for the hobbyist, anyway.

Thanks, Dave, for making this video.  I thoroughly enjoyed watching all of it with great interest.
 

Offline PeterL

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Re: EEVblog #974 - PCB Layout Walkthrough
« Reply #18 on: February 26, 2017, 07:57:48 pm »
Dave, maybe I missed it in the video, but have you checked if you have the nixie's right side up? I ask, because on the datasheet at 2:00 they have pin 12 upwards, whereas you have pin12 downwards. 

Also if you really want to avoid via's as much as possible you could swap pin's around. That would be at the cost of a messy schematic though..
 
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Offline Unixon

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Re: EEVblog #974 - PCB Layout Walkthrough
« Reply #19 on: February 26, 2017, 09:59:59 pm »
Dave, do you use grid alignment during component placement? I find it much easier to work on layout and routing when components are [next to] perfectly aligned. Personally prefer 50-mil to 25-mil grid for coarse alignment all over the board, 5 mil grid for fine alignment of neighbor components (passives to IC etc).
 

Offline 22swg

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Re: EEVblog #974 - PCB Layout Walkthrough
« Reply #20 on: February 26, 2017, 10:48:35 pm »
Thumbs up indeed, Dave , not seen PCB layout vid before, quite an education  :clap: 
Check your tongue, your belly and your lust. Better to enjoy someone else’s madness.
 

Offline DrChiron

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Re: EEVblog #974 - PCB Layout Walkthrough
« Reply #21 on: February 26, 2017, 11:05:13 pm »
Dave: This is redundant to 2 comments I left under the you-tube video.
The Russian Nixie datasheet shows the bottom view pinout for the display. I noticed that you chose to capture the clock PCB Nixie part drawing from the rear of the CLOCK board (the pinout there matches the datasheet). When you created the Part Spec for the Nixie Tube I noticed that the upper left-hand part label indicated TOP SURFACE, although you had just pasted the captured bottom view image there. I think you may have all 8 of your Nixie pinouts upside down!  Dr Chiron
 

Online EEVblog

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Re: EEVblog #974 - PCB Layout Walkthrough
« Reply #22 on: February 26, 2017, 11:46:44 pm »
Dave: This is redundant to 2 comments I left under the you-tube video.
The Russian Nixie datasheet shows the bottom view pinout for the display. I noticed that you chose to capture the clock PCB Nixie part drawing from the rear of the CLOCK board (the pinout there matches the datasheet). When you created the Part Spec for the Nixie Tube I noticed that the upper left-hand part label indicated TOP SURFACE, although you had just pasted the captured bottom view image there. I think you may have all 8 of your Nixie pinouts upside down!  Dr Chiron

The datasheet I have has the pinout as a bottom view, so it is correct that I flipped it. I have checked this with the actual tube.
I didn't copy the component from the bottom side, it was just the bottom side view. PCB's are viewed "through the board".
« Last Edit: February 26, 2017, 11:51:33 pm by EEVblog »
 

Online EEVblog

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Re: EEVblog #974 - PCB Layout Walkthrough
« Reply #23 on: February 26, 2017, 11:47:36 pm »
Dave, do you use grid alignment during component placement? I find it much easier to work on layout and routing when components are [next to] perfectly aligned. Personally prefer 50-mil to 25-mil grid for coarse alignment all over the board, 5 mil grid for fine alignment of neighbor components (passives to IC etc).

Yes, I thought I showed that? I used 1mm placement grid.
 

Online EEVblog

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Re: EEVblog #974 - PCB Layout Walkthrough
« Reply #24 on: February 26, 2017, 11:49:34 pm »
Dave, maybe I missed it in the video, but have you checked if you have the nixie's right side up? I ask, because on the datasheet at 2:00 they have pin 12 upwards, whereas you have pin12 downwards. 

Yes, I checked.
That datasheet is different to the actual one I had, I just didn't have it scanned.

Quote
Also if you really want to avoid via's as much as possible you could swap pin's around. That would be at the cost of a messy schematic though..

I mentioned that.
 


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