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Fuzz

Wilson Fuzz – Design PCB

In a very … very, very lengthy video I go through process of designing a PCB for a simple effect – a Fuzz Face clone. I covered building one before, but this time I thought to use it to go through how I design a PCB. For this series I’ll call this pedal Wilson Fuzz.

The video is at the very bottom of this. This post is really an index for that video with all the relevant links. Video has chapters but if you saw something and you can’t find it again, I put some time marks here so you can search for the keywords and hopefully find what you’re looking for.

I covered a lot in the video, so let’s get started.

Project Files

Oh, but before I go, it’s good idea to add two most important links here:

Template Repository: https://github.com/barbarachbc/pcbwaytemplate This repository had files for my template. I either use template or a previous project as my starting point.

Wilson Fuzz project repository: https://github.com/barbarachbc/wilson-fuzz Here I added all project files – KiCad projects, library files used, BOM etc.

Intro

00:00 intro & what are we doing

In this video I’m doing a PCB design, from start to finish for a simple Fuzz Face clone I called Wilson Fuzz. I made it more complicated than I had to by choosing a very small enclosure, and that probably added at least an hour to the video. But it also makes it more interesting.

01:50 Why are we doing this

It’s a simple circuit, but still meaningfull and great sounding. Also, even a small circuit is still complex to design for and create a physical thing.

02:30 KiCad

We’re using KiCad. It is simply fantastic program, free and very powerful.

04:02 My general approach

I already did this before, and if you go to the build page for it, you can see how I normally approach doing things. I normally do a SPICE simulation and some analysis. Then I do breadboarding and some experimentation to understand how sound changes with playing with different components. And finally I complete the build.

For this build, I’m using using BC549C instead of BC108C as I did originally. I did experimenting with different transistors then, so I knew it will work just fine. I still did breadboarding and made sure it worked.

05:53 Before we start

Good idea is to use a template to get you started. I either use a template or I use a previous project. The reason for this is, if you know which fab house you’re going to use, it’s a good idea to configure your rules to validate for limitations of the manufacturer.

For example, PCBWay has a whole page dedicated to capabilities and they even have a sample project for PCB Design Rule Checks

Other templates: https://github.com/sethhillbrand/kicad_templates

Create Project from Template

09:05 Create a project from template

You can find the template I used here.

Reference manual with details of which file is which, configuration etc.: https://docs.kicad.org/master/en/kicad/kicad.html

Drawing Schematic

I’ll just give a list of time points for things I covered, you’d really need to watch this, I cover a lot here if you haven’t used KiCad before.

12:50 Note on the transistor

13:52 Start drawing schematic

Here I covered: adding a device – placing devices/components, copy/paste/delete, moving around, trying to keep the diagram as close as possible as the schematic from the previous posts. I also make notes about pinouts – BC549/109C. “E” – for edit, doubleclick, right click etc. changing designators, properties, rotate/flip/mirror, wiring components (W), Ending line (end), label wires … phew

23:16 GND, adding power symbols (grid, changing grid)

26:19 Setting values for components

29:30 ERC (Electrical Rule Check) & Jacks

ERC is your friend. It helps us making sure that everything is connected. Make sure you always review the diagram, don’t rush or you’ll make mistakes. ERC doesn’t know if you connected things correctly, or that your diagram is correct. It just checks if everything is connected!

Bill of Material & Footprints

36:28 Before PCB can be created we need BOM

Without setting all footprints our Board Editor will show an empty sheet. Essentially, we need a bill of material of some sorts (we won’t know footprints if we don’t know which physical components we will be using).

39:00 Discussion about footprints – variations

39:42 Mouser BOM + distributor vs specialized shop…

See if this works: my shared BOM. Otherwise I have a csv/excel in the project.

Some more details on getting more information about your components etc:

41:30 – Datasheet for transistor

42:26 warning about photos of components

43:30 setting footprints

48:20 (short pots discussion)

Using 3rd Party Footprints

51:42 Using 3rd Party Footprints (finding correct pot footprint)

Here I was finding missing footprints through Mouser/Component Search. Then setting up folder structure for custom footprints and then 56:37 configure KiCad to use these folders

Continue Adding Footprints

1:00:28 Adding footprints for CAPs

And some discussion on CAP size and datasheet usage.

1:12:45 – highlighting components between PCB & Schematic

1:13:33 Adding Footprints for Jacks

We’ll be using header footprint instead of real jack footprints because we will use wires instead of PCB component.

1:17:00 TS pins – modify symbol for schematic in Symbol Editor

Modifying Tip and Sleeve pins to 1 and 2 so I can use header pins

Enclosure, Board Edge Cuts and Fitting Components

Very important to note – enclosure is limiting our PCB size and how we can fit everything else – pots, foot switch, LED etc. And this is very, very important thing to make sure we get right.

1:19:55 Enclosure and Board Edge Cuts

1:25:00 – I had said 33.5 but I changed it to 35mm – note that this will be important later. I don’t really know how I messed it up here, but I checked later and fixed it. It’s very important to check and verify your work often.

Here, I also covered: 1:26:35 changing grid 1:29:16 Fitting potentiometers onto the board 1:30:30 courtyard 1:31:50 Doublechecking pots pinout and placement 1:37:50 Discussion on PCB Layers (short) & changing layers for text/silk screen 1:41:33 Stand-off holes & logo

Adding 3D Model

1:47:24 Adding 3D model

Here I cover: finding the correct model, downloading, edit footprint and set 3D model for the footprint and how to place it correctly, and finally update footprints from library.

Fixing Schematic

1:55:33 Case of the missing LED

I totally forgot to add LED!!! Had to fix up the schematic.

Arranging Components

2:05:24 Arranging components

We have to go through the trouble of figuring out component placement. Especially of the critical components – those that we need to mount on the enclosure, like pots, jacks, stompswitch. This is where I get myself in trouble for using such a small enclosure.

Routing the Board

2:19:22 Finally Start Routing

I mention here some considerations regarding trace widths – keeping in mind that we’re dealing with analog signal and some notes on connecting ground.

2:31:03 – downside of the grid being too small!

2:33:10 DRC (design rule checker)

This is super important – DRC is our friend!

2:35:18 Rearranging components and re-routing

2:39:37 DRC pt 2 Dealing with violations

Sorting out courtyards overlap, silkscreen clips and overlaps with other silkscreen, end of the board and solder mask.

I really had to go through all violations and resolve them!

Finally Finished

2:52:49 (finally finished) Finalizing silk screen

2:56:32 Note: what I meant here – we don’t really care how the traces on the board look as long as the pedal sounds great! 🙂

2:56:42 Print and validate the board size

Print the board!!! This is very important – you can verify if the board can fit your enclosure. Also, if you have components, I suggest you lay them out on the printout to see if they are going to fit.

2:57:47 Size check failed!!!

… and I finally got to pay for my mistake from earlier. Tip: Pay attention, double check 🙂 always

Making the Board Smaller

2:59:07 Making the board smaller

Since I messed up the boad size, I had to make the board smaller, which meant I had to move stuff around. Very painful … and added extra, like 20 minutes to the video.

3:06:00 Check the hole clearance and fixing it

3:11:40 Finishing the board finally

3:16:40 Final Print, Cut, Test Fit

As you may have realized, I’m big into verifying everything!!!! And we can fit the board!!!!

Ordering PCB

3:21:54 Ordering PCB (using a plugin)

Here, I show how to install PCBWay plugin for ordering PCB. But you can see that there are other fab houses in the list there so you can use whichever you want. The plugin makes it so simple to order. Easy!

Summary and Final Words

3:27:03 Summary and Final Words … phew, finally. Maybe wait for the next video to see if this works before doing it yourself??? 😁

Video

Epic does not even start

Conclusion

This was a very long process. It took me weeks to prepare everything to make sure I could pull this off. I just could not make this under 3 hours, and in reality I was recording this over a few days. Still, there are some rough edges, but this is a real thing. The boards are ordered and we just need to complete the pedal.

There’s more to come.

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