Bona Fide Module Design Check-List

[radiokoala]

I am wondering what are some of the practices that would let you release a module that would make most of the customers happy – talking here some of those which not everyone does but if in a perfect world they probably would have?

Aside from shipping modules for free instead of selling them for moolah what comes to mind is:

1. Reverse protection on +12V and -12V busses. Still not everyone thinks it's superior of an approach to letting people blow three hundred buck modules by accident.

2. Buffering inputs / outputs.

What else?

Also, some pro-tips and engineering advice is welcome. I am by no means an electronics pundit or know-it-all (currently I am at measly 0.05% of knowledge one can have), but my suggestion would be to go after SSI version chips than e.g. V2164s, as those can melt their own plastic coats off if positive/negative supplies are turned on not at the same moment but one after another as far as I recall, so yeah, that's good 1977 year-like behavior, I thought we could have improved with time... correct not always.

Finally, there is one “always good to do” approach-related question I do have and this one is with regard to putting 0.1uFs between positive power supply voltage and ground. I have seen many DIY kits / modules etc where it was done for every chip and can't recall anything (it may exist) where it wasn't done. Now my question is, do we have this crappy of the power supplies where this could be an issue for things like CMOS ICs, timers etc? Not everyone's is linear but mostly everything is stabilized or stable enough if we are talking switching power to probably really affect things a big deal (I may be wrong ). Talking unsolicited triggering on unused inputs – sure, that may be needed and would probably be more useful than between Gnd & Vcc.

So, in other words, I wanted to ask if 0.1uF between those is bona fide / mandatory always or there are situations where it's OK to skip this (extra-?) step? In particular, I'm interested in TLC755, CD40xx, TL07x and stuff like that.

I hope that this thread proves useful for beginner engineers like me and helps them/me/us to create a more quality product and potentially avoid mistakes or excessive headache. There is malign intent, of course, and consciously disregarding safety measures, but then some people may not have the experience needed to know they should design their stuff a certain way and account for x/y/z and include a/b/c...

All the very best & thanks all!

[TumeniKnobs]

Here’s a bunch of ergonomic features I’ve come to like/desire on modules:

Shrouded power header
Clearly distinguishable inputs and outputs
Legible fonts big enough to read
LEDs that aren’t too bright
Flush mounted LEDs (so they can be dimmed with film if necessary)
Chunky knobs that don’t wobble
Finger room for said knobs
Knobs with position indicator on top
Elongated mounted screw holes

Just my 2 cents. Cheers!

[radiokoala]

Quality 2¢, worth a – Thank You!

[franktropez]

In addition, and somewhat in line with the things TumeniKnobs already mentioned; make sure that the pcb's keep well clear of the edges of the frontpanel, I've a few modules that sort of disregard the standard in that way and I now steer clear of those manufacturers. It's like a big fuck you to the user and the eurorack standard just to be able to claim embigulated functionality in less hp. I don't want to stress about a module possibly shorting to another or the (in)side of my case.

This post by North Coast Synthesis goes through a whole bunch of design mistakes and I've found it to be very informative: https://northcoastsynthesis.com/news/de ... chematics/

In general I think it's worthwhile digging through his blogposts as he shares a great deal of valuable info on designing circuits and modules and seems to hold himself up to a high standard.

Finally; something that makes me very happy as a end-user/consumer is a well-written manual that doesn't make any/too many assumptions. E.g. explicitly mention what voltage ranges are expected on the inputs and outputs so I don't have to get out a multimeter to find out what needs to be sent to a module to get the best wiggle resolution.

[Bethany]

This post by North Coast Synthesis goes through a whole bunch of design mistakes and I've found it to be very informative: https://northcoastsynthesis.com/news/de ... chematics/

*bookmarks, feeling a bit sheepish/guilty about two of the mistakes*

[radiokoala]

Thanks franktropez, a golden reply! So much to learn from that Matthew's publication – I have been mentioning him in every third or so post in the DIY sub recently, things like his expo converter feature article and in general, but I haven't come across that one prior to your mention, largely appreciated.

In addition, and somewhat in line with the things TumeniKnobs already mentioned; make sure that the pcb's keep well clear of the edges of the frontpanel, I've a few modules that sort of disregard the standard in that way and I now steer clear of those manufacturers. It's like a big fuck you to the user and the eurorack standard just to be able to claim embigulated functionality in less hp. I don't want to stress about a module possibly shorting to another or the (in)side of my case.

Good point! Worst offender was my own DIY build where I substituted one film cap with the two as I lost it or damaged or something, and one was sticking to the opposite side of a PCB, mounted vertically. So you had to tilt it sideways before inserting and then it'd be find, but super-fiddly still, and if there was a deep module to the left of it, it wouldn't help still. I eventually fixed that.... some five-to-six years later. Anyhow, I think I've seem some factory-assembled modules too, which were worse than the rest in that regard. It is a very good point!

This post by North Coast Synthesis goes through a whole bunch of design mistakes and I've found it to be very informative: https://northcoastsynthesis.com/news/de ... chematics/

I quickly skimmed through the main points and as an “electronics hobbyist” most of that is “oh wow” to me and is filled to the brim with new information, but I felt good that at least I realized an RC filter without capacitor wouldn't be an RC (right? ) and also his point about not using all pins of power connector. Luckily, I have at least some semblance of common sense and understanding of resistance and wiring circuits to see the potential problems this can cause.

So, with these two under my belt (out of, what: ten? issues that he's addressing) and, roughly, 2/10 score in this “Bad Design Issues You're Familiar With” I already feel happy enough to hit >0 already to claim now, 9 in the morning, that nothing today will make my day more than this. (And maybe I know of a few more, I scrolled through very quickly. )

In general I think it's worthwhile digging through his blogposts as he shares a great deal of valuable info on designing circuits and modules and seems to hold himself up to a high standard.

Some of my favorites this far (top-5) in learning about electronics are Designing Analog Chips and History of Electronics by Hans Camenzind, CMOS Cookbook by Dan Lancaster, IC Timer Cookbook by Walter G. Jung (I'll get to Op-Amp one with time; in my current design I am not reliant on those other than buffering & CV summing. I can see the big potential in working with these: OTA VCFs etc, but so far I want to focus more on learning the CMOS Logic and many ways of using 555 inside-out before trying to become a jack of all trades and jump from subject to subject. My new weekend's “invention” — “handcrafted ocean noise” doesn't sound too bad and so does the rest of my PG-13 Poodlegroomer VCO, so I'm probably on the right path of focusing on one thing at a time and it was the right decision. )

Finally; something that makes me very happy as a end-user/consumer is a well-written manual that doesn't make any/too many assumptions. E.g. explicitly mention what voltage ranges are expected on the inputs and outputs so I don't have to get out a multimeter to find out what needs to be sent to a module to get the best wiggle resolution.

Good point! 4ms PEG kit build documentation doesn't include schematics and it was awful reaching out to customer support saying that the LED on Ping or Cycle button had stopped blinking after it did and getting advised to mind/check the polarity of an light-emitting diode (sure it resoldered itself the wrong way after having worked previously ).

I wasn't on the level of understanding to blame the transistor first thing back then and was basically left to troubleshooting this all on my own and then eventually Alex of L-1 fixed it in half-an-hour, but despite his company name also being a short name containing a letter & a digit, he by no means was 4ms Company so I'm not feeling particularly thankful after having got zero useful suggestions over like three emails. Sure, DIY kits and such are aimed at more advanced people in general, but how exactly lack of schematics would help even more accustomed synth engineers to troubleshoot/repair?

In general, I feel most likely I will never ever buy a DIY kit or a PCB without schematics, it is just asking for the problems and is not something that I'm willing to support. I would have zero complaints about reaching to 4ms about problems with my build if there was schematics. As is I was told that they wouldn't share it and I was left with a (custom?) IC-based on module that I had no clue WRT what went where and where to start looking for a possible solution.

...Finally; something that makes me very happy as a end-user/consumer is a well-written manual...

Here hoping to make you a bit more happy by sharing my XWY END-ALL BE-ALL patch collection. Hope you enjoy!

This post by North Coast Synthesis goes through a whole bunch of design mistakes and I've found it to be very informative: https://northcoastsynthesis.com/news/de ... chematics/

*bookmarks, feeling a bit sheepish/guilty about two of the mistakes*

Love me some border collies! I made a collage in Photoshop and printed on glossy 25x38 paper for a (Polish) girl [there is this song, “Polish Girl” by Neon Indian I've always had in my player ] like five years ago featuring some fun shots of those with a muffin on their head or posing on a stepladder or riding skateboard. The end result was that she didn't really fell in love with me—as in: at all!—but nonetheless would have it on a wall of her room in a university dorm facing her while resting in a bed.

On more on-topic note, can you talk more about those two? Will pay attention to that more and keep in mind in the future. (Or just send a pm if you will if you'd feel too ashamed to confess in public. )

cHEERs!