Bring out yer Diptrace

ok i finally found the treasure trove of knowledge i need to finally make a knockoff durham crazy horse pcb for my buddy.

time to start from page 1 lol
I actually did a Crazy Horse circuit PCB a few months ago, my layouts aren't as symmetrical or tidy as is typical of this thread (hence why I don't post 'em), but I'd recommend a different taper for the "VOLTS" control since all the fun sounds are in the bottom half of the control Screenshot 2024-04-30 at 10.08.22 AM.png
I keep coming back to the Biggus Dickus but I keep making the Dickus smaller. 1590A is about as tiny as I think it needs to go 😂

Think this is my first SMD layout without a via. Getting better! I don’t trust jlc with electro caps quite yet but I’m gonna just thru hole mount the little fellas anyway, basically takes the same footprint size.

(I should rename it Smallus Dickus before I send it off to get fabbed)

I've been using two breakout boards in all of my recent builds. One is an I/O board with MOSFET-based over-voltage and reverse polarity protection; the other is a "smart" microcontroller-based relay bypass board.

I'm playing around with combining them into a single board that uses some of the (relatively) new ATTINY 1-series microcontrollers:

IO Mockup.png

The 1-series has a lot of advantages over the earlier ATTINY microcontrollers, including UPDI programming, which allows you to program the microcontroller with just three terminals. The three terminals are hidden under the output jack, so they won't obtrude in an assembled build. (The jacks would hide the unsightly vias, too.) And they're cheap, too, around 55¢ from Digikey or Mouser.

Here's the schematic, for anyone who's curious:


One other feature that I've been working on is an over-voltage warning indicator. My previous iterations of the microcontroller included an unused pin, PA7. The new version connects that pin (PA7) to the junction of a 7.5v zener diode and a 1M resistor:


As the VCC increases above the zener voltage (VZ), the voltage at PA7 increases by VCC-VZ, until the over-voltage circuit kicks in, at which point the voltage at PA7 decreases to a few nanovolts:


When the microcontroller detects that the voltage at PA7 is below a certain level, say 0.5v, it would start to blink the bypass LED, warning the user of over-voltage. Without the blinking LED, there's a sizeable chance that the user would just think that the pedal was broken.

This might seem like over-engineering to some, but I've seen over-voltage kill many more pedals recently than reverse polarity. As a bonus, it's not meaningfully more expensive than just doing a relay bypass breakout board.


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@PedalBuilder I love your work! Totally agree that if you're going to make an IO board then it should be as utilitarian as possible.
Are you getting these assembled? You could probably swap the electrolytic 100uF for a MLCC (or 2 in parallel) to lower assembly costs.

I took your approach with a prototype recently and really like it:
I need to re-work my layout to take up more horizontal space and less vertical (I was trying to build for 1590B as well, but fuck 'em).
I do my jack spacing with the PPCB drill template dimensions and found that taking the PCB away from the corners can help if you have a tight fit (due to dodgy drilling). It helps avoid the enclosure lid edge. Ie.


The ATTiny approach is pretty cool. You're using a latching relay, if you used non-latching you could drive two relays for dual-channel modes off a single footswitch. Though my experience is that dual footswitch is a better user experience. (KISS).
Thanks, @szukalski! Nice boards you've got there!

I've been getting mine partially assembled by JLCPCB. Between the two boards, I've had them assemble everything except for the electrolytic cap, microcontroller, and zener diodes. As a general rule, I try to avoid using non-basic parts unless it's a component that's way cheaper from JLC, like a P-channel mosfet or some of their relays.

In this iteration I've been able to squeeze the dimensions down to 57x30mm, with a 9mm cutout for a flush-mounted outie jack. Ideally I'd like to cut the 30mm down to closer to 27mm, but the big electrolytic cap has made that difficult. If a ceramic cap will do the job just as well, I think that 27mm might be possible. Thanks for the idea!
I really love my FZ77 (which is a DAM FS-77, which is a Tone Bender Mk3 with an AMZ tone control) and I wanted to redo it in Kicad with some niceties for building (namely bias trim pots). This works equally well with PNP or NPN if you have a leaky enough transistor for Q3. (NPN needs trivial changes).

Love it. Wah shells are too expensive to throw away and most of the stock wahs out there are underwhelming, I love to see the exploration of better wah sounds.

Since it’s a one off for me, I’ll use the Big Vishay caps I love so much but can’t use anywhere else except for amp builds.

I’m going to forego the “Bird”/“Echoes” switch on the wah and just make a separate box I can plug into for the screechy stuff when I want it.

I’ll be making a Fixed 125B version of this as well.

Mainly just trying to use up all the inductors I find myself with!
@PedalBuilder really got me interested in his smart IO board so I rigged up my own:


Harder to make this work with basic parts from JLCPCB, so the cost is higher than Chuck's basic relay, but the cost is worth the convenience.
Still waiting to verify, but if I did it right (and I often don't) then this should work with 1590B.

In other news, JLCPCB doesn't charge to remove the order number any more! Rejoice!