Wow @Brett, what a treasure trove of information. I will probably re-read this a lot, thanks.
You've already anticipated my thinking about having the LFO and power section of the Univibe on a separate board to the audio circuit, and with their own separate ground arrangements, connecting as close as possible to the +/- pads.
I so appreciate you taking the time to share your learning with me.
Clean layout! I like the "flexible" resistor footprints. If you don't mind sharing, how are you handling the relay bypass? I see an SOIC-6 footprint, is that being used as the relay controller?
Thanks a lot. Yes, I use the smallest PIC available, PIC10F322. I was inspired by an old @bean design. I have implemented four modes of switching that can be cycled on power-up: latching, momentary (non-latching), momentary after long press, and switched on after power-up. Other than that, there is nothing fancy. If I want to use the magnetic switch, the three contacts at the bottom can be used for the hall sensor.
I can share the schematic but there is nothing you could not figure out if you know how to connect the switch to the MCU input.
Well, I had my first batch of PCBs arrive yesterday: the pcb I'd posted before, my own footswitch daughterboards, and a board with the Dyl-Ei Fuzz Apprentice. I quickly threw together one of each, and put the Dyl-Ei in a box.
Everything worked! And it all sounds good! Thanks @Brett, again, for all the feedback.
I had a few glitches - I got one pot knob reversed, had a poor footprint for a 2N3904, put a film cap footprint instead of an electrolytic. But I'm pretty happy for a first try.
I've got about 15 separate projects on the go, but this is a Son of Screamer/Eternity hybrid with switches altering the high and low frequency response of the circuit. The hope is to get the best of both circuits in one. I'm building it for Christmas for my teenage daughter who is learning guitar at a fierce rate and loves all things John Mayer (hence the pedal name and cribbed lyrics). I decided it would be more fun to build her something flexible rather than going for a boring vanilla TS10 replica. I am pretending not to be bothered about the symmetry issues caused by the different switch and cap sizes on the outside rows haha.
I was definitely going to enlarge those 47N caps before getting the board fabricated But now I am going to have a long hard think about how to make the smaller switch footprint look bigger!
I was definitely going to enlarge those 47N caps before getting the board fabricated But now I am going to have a long hard think about how to make the smaller switch footprint look bigger!
Wondering if I can get some more feedback (just some basic feedback, doesn't need to be in-depth). These layouts aren't done (I need to add to polish a little and add labels, but the DRC passes). They're on the more complicated side for me. I've now done ~10 overdrives to various stages of completion, but those have fewer components.
I'm mostly wondering if the long traces and some of the clutter is likely to cause noise. These were fairly loopy schematics, but I did the best I could.
And then there's a Perfectly Usable Phaser (4-stage). As an example, I'm curious, in the top-left corner, whether having the traces cross is more likely to cause noise than routing the blue trace above the switch (a somewhat longer route). I don't have any sense for these things. Maybe it's a marginal difference but all the crossings add up?
See if you can tweak some alignment. Make it look a tad prettier
From experience, sometimes placing electrolytic caps too close to other components has led to complications.
What trace widths are you using? I tend to go parallel to Bean's PCB layout tutorials and go with 18 mils for voltage rails and 10 mils for signal traces. Sorry I'm doing it in freedumb units, but I haven't switched over to metric for this yet.
Some of those comments might not work depending on your footprints; e.g. (using Bean's libraries) I'm used to 1/4W resistors matching up to one rank of a, 8-PDIP package.
Those are just knee-jerk thoughts, and I'm a bit tired, so
@rwl Looking good in general. Mostly aesthetic preferences, though I am no EE!
I would look at some of the placements around the IO and pots. For example, in the compressor, there are high standing capacitors around the Makeup and Attack pots. That may be a little annoying to solder.
Similar with the IO pads at the bottom. There's a cap right next to it which limits the angles you can solder from. Maybe not an issue for you, but that sort of thing has annoyed me enough from time to time.
If you're doing dylan159 designs, remember the license that he's released them under. You should be making any works derived from his designs open source and available. Whether you actually do or not is your choice of course. I have seen others declining to honour this agreement, and it runs against the spirit of what is being done in the community.
@jessenator - You know, it didn't occur to me until you marked up the layout that it would be a lot easier to keep things aligned by drawing some helper lines in an unused layer in the editor itself!
I'll keep this in mind. I don't mind having something tall to one side of the pots, but I do really hate if the pads are tightly enclosed on two sides.
Yes, my intent was to share them. I'd like to build up a collection of pcbs on github similar to yours, once I've validated the layouts work. I've had most of your Dylan159 layouts printed and really like all of them (except the Clown Centurion), so I figured I would complete the collection. I also find Dylan's schematics very easy to read.
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For reference, after the feedback, this is what I ended up with, and am going to get fabricated.
Compressor:
And Phaser:
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I might throw out a few cases I encounter, where I'm not sure about whether there's any functional difference. Here's a starter, the blue trace is coming from below the screenshot.
A. Wrap around (at minimimum clearance):
B. Wrap around (add padding):
C. Cross over:
D. Makes no difference.
Thoughts? I've tended to opt for B if there's space on the board since it feels "safest" (farther from other components), but it's also the longest trace.
In a case like this I would modify the schematic so the blue trace connects to lug 3 and the red trace connects to lug 2.
As far as routing the traces as-is, I would look at the surrounding traces and determine which of the two in question (red/blue) would benefit more from the clearance.
I suppose that guidance only applies for when lug 2 and only one of the other lugs are populated, since basically the only important thing is that the two traces should be connected somehow when the switch is flipped
I know you wanted feedback, so/though I'm going to suggest having a switch to cancel the feedback... (I vaguely recall this is a popular mod, to disconnect the feedback path).
Just in case you haven't read it, do read "The technology of Phase Shifters and Flangers" by RG KEEN.
You said you sent these off to be fabricated, but did you check to make sure your DRC passed after you revised the boards?
Those 10K resistors (vertical oriented next to pins 1-4 of the TL074) may have their pads merged (not sure if this was intentional). Additionally, the trace leaving the vertical 10KΩ on the left has zero clearance to the uppermost horizontally oriented 10K resistor.
I don't claim to be an expert on these things, but why cram so much into such a tiny space? You have the real estate to give your traces and pads a little more breathing room.
@Brett - here's what it looks like close up - it seems to meet the exclusion requirements, it's just hard to see in the zoomed out screenshot.
Your broader point is correct, I could make better use of the space... I got tired of moving the larger blocks of components around every time I shuffled the layout, then having to reroute all the connecting traces to see if it works out. I see now KiCad offers a "drag" functionality (hotkey D, can't have traces selected) that rubber-bands the traces outside the selection, but it's still pretty janky.
But now I am going to have a long hard think about how to make the smaller switch footprint look bigger!
