Author Topic: Help with first layout  (Read 4039 times)

Jebus

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Help with first layout
« on: January 23, 2017, 01:01:14 PM »
Hey,

I got access to CNC PCB mill and lots of cheap material. It can do single sided PCBs (drills holes and everything). So, I just did my first layout for Big Muff with Eagle.



So, even I think it looks messy. ;D I tried to move parts around and redo connections, but that's pretty much best I could on first try. It's going in a 1590BB, so there's lots of room. I tried to put the parts bit more apart to make soldering more easy (no solder mask).

So, could someone more experienced take a look and let me know what immediate problems are there? Will the long connections (for example C2 to C4, C8 to C6 or volume pot to out) cause problems?

Lots of people seem to use 45 degree angles instead of 90 degrees. I've always thought this doesn't matter in audio frequencies (only higher). Does it?

Any other tips or advice?

Thanks!

Edit. One more question: what are those blue patches at bottom right, below volume pot and at top right corner?
« Last Edit: January 23, 2017, 01:09:39 PM by Jebus »

PhiloB

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Re: Help with first layout
« Reply #1 on: January 23, 2017, 02:30:06 PM »
I would make the isolation a bit more and also make sure there is more space between traces and pads to reduce the possibility of connecting things that are supposed to be connected:)
Also, at least one trace touches a pad:



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jkokura

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Re: Help with first layout
« Reply #2 on: January 23, 2017, 02:52:36 PM »
I once had someone explain to me that circuit boards are like long lines of people standing shoulder to shoulder. Each time the 'power' gets turned on, all that happens is that the people in the lines nudge the person next to them until the end. It doesn't really matter how long the lines are, because this nudging is almost instantaneous.

So in the end, 45 degrees or 90 don't really matter, but they can make routing a little easier at times. Neither does the length of connections, because it takes a really, really long line before the electronic latency is noticeable, and there's no way you could ever fit even the largest enclosure with that much trace length.

As a PCB design guy of some sort, I really encourage people trying to up their game with two things:
1 - look at other PCBs out there. For instance, this is a circuit that has been done again, and again, and again. Doing it yourself feels fantastic, but it's okay to look at someone else's design to learn what they did, see things through their eyes.
2 - when you're designing the layout, don't just think about the traces, think about what it will be like to build the PCB and put it in an enclosure. Are you happy with the way the parts are on the PCB? Have you left yourself enough room in the right places?  Is the PCB the right size and shape? Do you have the connections you need to make in the correct place to make the build go smoothly? I personally work hardest at this part first, making sure the orientation and arrangement of my parts are satisfactory, then I start working on the traces themselves, and adjust the parts on the PCB to make both the arrangement and traces work.

But I've done hundreds of layouts at this point, so please don't feel pressure to meet any sort of standard. I still remember making my first layouts, and the learning curve will allow you the experience over time.

Enjoy it! PCB making is fun!

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m-Kresol

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Re: Help with first layout
« Reply #3 on: January 23, 2017, 02:57:27 PM »
that's not bad for a first try. mine looked quite similar. Once you got that step, I've found it nice as a start to set some goals, like "I want the pots in that order/positions" or supply pads arranged a certain way. this constraints make it harder for sure, but the overall ease of building is worth it. you could make your layout a quite bit smaller just by moving components closer together in the arrangement as they are now. No idea what enclosure size or restrictions you have.

the blue patches you've got are probably some "keep out" areas. Check the active layers (upper left corner) and you'll find one that has the correct colour and pattern. keep out areas are usually areas where ratsnest does not fill in and stuff like that.

move r5, r16 and r15 a bit to the left. you'll eliminate the 90 turn to the clr. 90 should generally be avoided for some reason and I would just stick to the 45 drawing tools.

trace going from c8 to c5, check that it's not touching C7. use the DRC tool to check for any errors. it will tell you if traces are too close to pads and stuff like that.
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wgc

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Re: Help with first layout
« Reply #4 on: January 23, 2017, 08:21:11 PM »
Agree with most comments, especially those aimed at ease of assembly.

If you're going to cnc, try to optimize the cuts and trace widths to make the most of your cutter diameter. In general make sure that your diameter is a little thinner than your cuts, but not too much. Otherwise, it will take more passes to cut (dia too small), or worse (dia too big), you take away material off your traces.
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Jebus

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Re: Help with first layout
« Reply #5 on: January 24, 2017, 01:57:48 AM »
Thanks a lot to everyone for suggestions and information! I moved parts bit more and here's the current version:



I would make the isolation a bit more and also make sure there is more space between traces and pads to reduce the possibility of connecting things that are supposed to be connected:)

I tried moving parts a bit to get more space between traces and pads.

Do you mean the isolation between pads and other stuff? How do I increase that that?

I once had someone explain to me that circuit boards are like long lines of people standing shoulder to shoulder. Each time the 'power' gets turned on, all that happens is that the people in the lines nudge the person next to them until the end. It doesn't really matter how long the lines are, because this nudging is almost instantaneous.

So in the end, 45 degrees or 90 don't really matter, but they can make routing a little easier at times. Neither does the length of connections, because it takes a really, really long line before the electronic latency is noticeable, and there's no way you could ever fit even the largest enclosure with that much trace length.

Jacob

Thanks Jacob! Really informative post. I actually tried to look a bit for other peoples designs, but I think I was trying to look for way too specific stuff (like placements for all active components and so on). I'll try to study more of those. :)

No idea what enclosure size or restrictions you have.

It's going into 1590BB with top mounted jacks. No other restrictions.

move r5, r16 and r15 a bit to the left. you'll eliminate the 90 turn to the clr.

Thanks. I moved those around and I think its bit better now :)

If you're going to cnc, try to optimize the cuts and trace widths to make the most of your cutter diameter. In general make sure that your diameter is a little thinner than your cuts, but not too much. Otherwise, it will take more passes to cut (dia too small), or worse (dia too big), you take away material off your traces.

Alright! I'll need to check to CNC mill next Monday to see what size are the cutters. I've only ran a single test layout with it so far.

Jebus

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Re: Help with first layout
« Reply #6 on: January 24, 2017, 02:02:41 AM »
I tried moving parts a bit to get more space between traces and pads.

Do you mean the isolation between pads and other stuff? How do I increase that that?

Ah, it was directly at polygon properties. I tried increasing it, does this look better:


Jebus

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Re: Help with first layout
« Reply #7 on: January 24, 2017, 08:32:30 AM »
Did some more moving around and increased the isolation bit more. This is surprisingly addictive..  ;D


m-Kresol

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Re: Help with first layout
« Reply #8 on: January 24, 2017, 11:27:05 AM »
check your schematic too. it seems to me that your power section is wrong. 9V goes to D5 (protection diode??), but the other end of the diode is also connected to 9V via a resistor...

the traces from R12 to R5/R16/CLR you can save the turn and run a straight line if you go from R12 to R5 rather than R16.

any reason for the increased leg spacing on C10? also if you move C10 directly under the right pad of D3 and align the lower pads of C9 and R13 with the lower pad of C10 you will make things easier too.
rotate Q2 90 to the right, this will also clean things up. also you can rotate R10 180 and reroute the trace that is now going from its lower pad to D1/D2
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Jebus

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Re: Help with first layout
« Reply #9 on: January 24, 2017, 11:51:38 AM »
check your schematic too. it seems to me that your power section is wrong. 9V goes to D5 (protection diode??), but the other end of the diode is also connected to 9V via a resistor...

Good catch! Yeah, I thought I could do it like this:



Where +9V(T) would only mean the pad and +9V would automatically connect to other +9Vs in schematic, but that doesn't seem to be the case. Now it should be fixed.


the traces from R12 to R5/R16/CLR you can save the turn and run a straight line if you go from R12 to R5 rather than R16.

any reason for the increased leg spacing on C10? also if you move C10 directly under the right pad of D3 and align the lower pads of C9 and R13 with the lower pad of C10 you will make things easier too.
rotate Q2 90 to the right, this will also clean things up. also you can rotate R10 180 and reroute the trace that is now going from its lower pad to D1/D2

Oh yeah, good ideas all. No reason for C10, probably just picked wrong component while drawing the schematic. :) I'll post updated layout later..

midwayfair

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Re: Help with first layout
« Reply #10 on: January 24, 2017, 12:24:19 PM »
I've heard that the 90 degree thing is for REALLY REALLY high frequencies, places where straight traces act like antennae and the frequency ends up polluting something else that the trace is pointing at. But that might be BS, you know? ;)

Brian told me that some fab houses might actually have problems doing them properly as well.
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Jebus

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Re: Help with first layout
« Reply #11 on: January 24, 2017, 12:29:14 PM »
I've heard that the 90 degree thing is for REALLY REALLY high frequencies, places where straight traces act like antennae and the frequency ends up polluting something else that the trace is pointing at. But that might be BS, you know? ;)

Brian told me that some fab houses might actually have problems doing them properly as well.

Yeah, I asked couple of friends, who work lot with higher frequency electronics, and they both said it won't matter at all with audio frequencies. Well, I guess its still good habit to avoid those. :)

I updated the PCB with Felix's ideas, did you mean something like this?



Edit. updated image. :)
« Last Edit: January 24, 2017, 12:39:06 PM by Jebus »

m-Kresol

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Re: Help with first layout
« Reply #12 on: January 24, 2017, 01:40:17 PM »
looking good! minor thing, more of a personal perfectionism actually.
you can run the R5 to R3 trace horizontally instead of diagonal.
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Jebus

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Re: Help with first layout
« Reply #13 on: January 24, 2017, 02:02:54 PM »
looking good! minor thing, more of a personal perfectionism actually.
you can run the R5 to R3 trace horizontally instead of diagonal.

Good idea, will do that tomorrow. Also should move R2 and R4 bit to left so I can lower Q1 and ground plane fills that "hole". :)


m-Kresol

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Re: Help with first layout
« Reply #14 on: January 24, 2017, 02:07:11 PM »
Also should move R2 and R4 bit to left so I can lower Q1 and ground plane fills that "hole". :)

that won't do the trick as the pour won't go in between the pins of the transistor. are you going to have some kind of solder mask?
I build pedals to hide my lousy playing.

My projects are labeled Quantum Effects. My shared OSH park projects: https://oshpark.com/profiles/m-Kresol
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