#81

I think this is the correct topic for this question, not entirely sure to be honest :x

Does anyone know what the normal/default way is of protecting outputs in Eurorack modules from someone plugging in another output?
Does this depend on the circuit of the module or is there a generic thing that can be placed in front of an output to do this?

In case it’s specific to the circuit/components in question: I’m mainly looking at the output of an opamp, AFAIK directly plugging in another output will fry the opamp in pretty much all cases so it would need some form of protection. What would be the correct circuit to do so?

I did find the following in this mw topic

In my experience, TL07X opamps will survive reverse power, briefly (although they’ll get very hot). However, 2164 VCAs will die instantly. I’ve fried quite a few this way. There is a way to prevent it, though: connect a Schottky diode between ground and -V. This seems to protect the 2164 (thanks to Neil Johnson and Oscar Salas for figuring this out, at the cost of several precious SSM2164s). I do this on all my boards, now, and we do it on the Intellijel modules as well.

#82

that mw quote seems to be talking about protection against polarity reversal.

someone please correct me, but i thought an op-amp output with a resistor (1k) is sufficient protection.

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#83

As @tehn mentioned, that thread is about reverse polarity, for example if a person plugs their power connector in the wrong way, swapping +12 for -12. Using a 1k resistor on the output is common, but it does depend a bit on the circuit because that method can be problematic for modules that generate CV intended to control pitch, as the voltage may vary slightly depending on the module it is plugged into. See for example the discussion: https://forum.mutable-instruments.net/t/modules-without-protection-resistor/8443/4

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#84

Ah, yeah, you’re both right, I didn’t pay enough attention. Still useful info of course :slight_smile:

Thank you both for the 1k resistor pointer.

Thanks for the link! I’ll have a read through it and see what I can learn :slight_smile:

#85

Those of you who do front panel designs with Adobe Illustrator, what do you do with the files after you’re done? It seems that front panel express and others don’t work with that format.

#86

I use aluminium pcb panels (cost about $12-20 for 10 so about $1 - $2 each). I convert the illustrator or photoshop designs to bitmaps and finish the panel and generate the gerbers in eagle.

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#87

After a little research, it seems that you could, for example :

  • in Illustrator, export your file as a DXF
  • convert the DXF to an HPGL (with Cenon, or Inkscape, or a similar software)
  • import the HPGL into FPE.

I’ve never done this myself, so you’d have to experiment to get sure the results are as intended.

#88

Front Panel Express is a bit of a pain in its specific requirements, and @thom’s solution to import HPGL into it seems sensible.

In general, DXF is a format that panel houses will be fine with. It’s a CAD format, not a graphics format. I belief Illustrator can do DXFs; annoyingly, none of the other illustrator competitors I’ve used other than Inkscape can (and I hate using Inkscape). But I tend to supply DXF as a format.

I also supply mechanical drawings:

image
image946×683 64.8 KB

These are not intended for anyobdy to make anything from; instead, they are the unit test for the DXF file - they show what the DXF ought to contain. Indeed, you could make your own panel by following these instructions, and you ought to get what’s in the DXF. Between the two, I cover most eventualities.

(I generate both from Fusion 360; it makes it easy to generate DXF for a surface, and indeed, to make mechanicals out of anything with relatively little effort. I have enough time invested in that tool to make it worthwhile, but wouldn’t recommend it just to get DXFs from a panel).

Another bonus recommendation for Cenon, that thing is a swiss-army knife. (My favourite use of it: adding SVG content to gerber files.)

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#89

Could you say a bit more about this process? Are there PCB fabs which offer aluminium PCBs? I wasn’t aware of that. What are the options for text and graphics?
I went through a period of making quite a few eurorack modules and tended to laser-cut acrylic for panels, but aluminium would be hardier and convenient if already ordering PCBs for circuits.

#90

allpcb and pcbway do them (I prefer allpcb’s ali pcbs). Text and graphics are whatever you like! You can use the copper layer for colour or texture as well, but I tend to just use the soldermask and silkscreen layers and keep it black and white. I make a bitmap in photoshop and then import it into eagle.

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#91

Would you mind to share more detailed (beginner friendly:) process of how you do that or maybe you have an eagle example you ok to share? Sorry if I am asking for too much not sure if it Is appropriate:)

#92

There are loads of eagle examples on my github…

There’s a writeup from Emilie Gillet on the MI forum - have a search for it - that’s a good starting point for using eagle to do panels…

My GitHub:

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#93

Great, thank you very much! Gosh, Emily is like endless source of knowledge.

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#94

Does anyone have experience / suggestions for hand-drawn circuit boards? I typically use Eagle and the straight line tool to draw curved lines with a bunch of segments.

I’d love a tool that would allow me to work with a stylus while maintaining some level of schematic cross-checking. I’m guessing this doesnt exist but perhaps someone has tried this? @infovore’s mention of Cenon feels like it could be part of this process.

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#95

Cenon probably isn’t a fit there - there’s no cross-checking or owt, it just happens to be a vector tool that will export to Gerber. I found it useful for interacting with silking layers, but wouldn’t want to trust it on copper necessarily.

#96

i love that you think your current designs aren’t wiggly enough :slight_smile:

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#97

With a large enough export and import using something like bitmap2component you should be able to do your copper layer in any vector graphics tool setting the correct width/outline as spacing, clear/fill the outline to check spacing, export as high DPI into b2c… Then you can draw using the pen tool or pencil tool to get as squiggly as you like.

Edit: I guess this doesn’t have any checking either

#98

PCBModE ( https://github.com/boldport/pcbmode ) is an option that allows you to layout in Inkscape and export Gerbers, though I’m not sure if it does any cross-checking. It is developed by the people behind Boldport and I believe it is used to design all of their project PCBs: https://boldport.com/shop?category=Soldering+projects

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#99

This seems to be good news for FrontDesign users who prefer or need to draw their designs with other software:

1 Like
#100

Only problem with Schaeffer is their prices…
Just got a panel made worth the price of few diy modules.
Top quality i must say.