Search found 2691 matches

by mskala
Fri Jan 15, 2021 9:41 am
Forum: Music Tech DIY
Topic: Experience with cheap panel manufacturer in china?
Replies: 11
Views: 326

Re: Experience with cheap panel manufacturer in china?

I don't need color prints, just black or white depending on the color of the panel (anonized black or brushed aluminium) Printing at all is going to make things more complicated because machine shops don't do it and they will have to bring in a subcontractor, regardless of whether it's colour or no...
by mskala
Thu Jan 14, 2021 4:46 pm
Forum: Music Tech DIY
Topic: Experience with cheap panel manufacturer in china?
Replies: 11
Views: 326

Re: Experience with cheap panel manufacturer in china?

The critical issue is printing. If you don't need them printed, there are a lot of Chinese factories that can make machined panels for you. But if you need them printed, well... When I started out a few years ago I contacted a number of Chinese companies through AliBaba and tried to get quotes on pa...
by mskala
Mon Jan 11, 2021 1:59 pm
Forum: Music Tech DIY
Topic: diy partial-kit frustration rant
Replies: 44
Views: 978

Re: diy partial-kit frustration rant

Thanks for the plug, KSS. Something I'd add is that as a largely DIY vendor, I'd rather have people buy full kits because those give me the chance to make a small profit on the parts and get paid for the sourcing work I'd be doing anyway to support my own builds. The percentage margin on PCB+panel i...
by mskala
Sun Jan 03, 2021 1:18 pm
Forum: Eurorack Modules
Topic: Why are so many vendors/manufacturers low or out on stock?
Replies: 76
Views: 3793

Re: Why are so many vendors/manufacturers low or out on stock?

My DIY kit sales are up. Assembled sales are down. I don't offer "PCB and panel" and don't feel I can afford to - with the smaller price tags on those, and people opting for them instead of kits, despite a higher profit margin on PCB/panel I'd have to sell thousands to make a living and the market i...
by mskala
Thu Dec 24, 2020 12:48 pm
Forum: Modular Synth General Discussion
Topic: what's so special about triangle core VCOs?
Replies: 18
Views: 1364

Re: what's so special about triangle core VCOs?

Also, very often a "relaxation" oscillator will be one where the discharge switch and voltage detection are done in a single component - like a neon lamp or a unijunction transistor. These aren't common anymore but were very popular, especially for hobbyists, back in the day when components were mor...
by mskala
Mon Dec 07, 2020 6:55 am
Forum: Music Tech DIY
Topic: Using SVG2shenzhen to make PCB panels
Replies: 11
Views: 512

Re: Using SVG2shenzhen to make PCB panels

I haven't used svg2shenzhen, but I think the folder full of .mod files is probably what you want. It should be usable as a footprint library in KiCAD's PCB editor. KiCAD uses the term "module" sometimes (including to abbreviate for the filename extension) where it means what most people call a PCB f...
by mskala
Fri Dec 04, 2020 5:07 pm
Forum: Music Tech DIY
Topic: Anything to consider for LED Diodes before CV output?
Replies: 10
Views: 268

Re: Anything to consider for LED Diodes before CV output?

htor wrote:
Fri Dec 04, 2020 3:32 pm
really enjoy reading your articles. thanks for writing them :tu:
Thank you!
by mskala
Fri Dec 04, 2020 10:04 am
Forum: Music Tech DIY
Topic: Anything to consider for LED Diodes before CV output?
Replies: 10
Views: 268

Re: Anything to consider for LED Diodes before CV output?

Yes, it's a standard series-resistor LED drive circuit. You'll need to find the forward voltage of the LED; subtract that from the driving voltage that you expect in the normal case to find the voltage drop across the resistor; choose how much current you want through the LED in the normal case; and...
by mskala
Thu Dec 03, 2020 8:34 pm
Forum: Music Tech DIY
Topic: Anything to consider for LED Diodes before CV output?
Replies: 10
Views: 268

Re: Anything to consider for LED Diodes before CV output?

Good point, hadn't thought of protecting outputs from potential inputs being patched. What's a good practice to go about doing this? I know of limiting voltages to a range using a circuit with Schottky diodes (from the Doepfer A-100 DIY page) but I'm assuming there is an easier way to do this with ...
by mskala
Thu Dec 03, 2020 11:57 am
Forum: Music Tech DIY
Topic: Anything to consider for LED Diodes before CV output?
Replies: 10
Views: 268

Re: Anything to consider for LED Diodes before CV output?

An LED is unlikely to add noise, especially not on a logic signal, but you may need to protect the LED itself against the possibility of someone patching an unusually high or low voltage into that output jack. People sometimes overlook that when designing output circuits.
by mskala
Sat Nov 28, 2020 1:13 am
Forum: Eurorack Modules
Topic: Individual module....dedicated power switch ?
Replies: 35
Views: 1010

Re: Individual module....dedicated power switch ?

I only noticed the first one because I was for a time trying to figure out how to make a submini toggle that was (off)-on-off. For the matrix switch bus splits of my new format. I wanted the middle to be on so the bat was vertical in what would be considered the default state. Then one way would be...
by mskala
Thu Nov 26, 2020 4:24 pm
Forum: Music Tech DIY
Topic: 100k input resistance... isn't
Replies: 89
Views: 2441

Re: 100k input resistance... isn't

You are a coward for making insinuations that you cannot back up with facts.
by mskala
Thu Nov 26, 2020 2:43 pm
Forum: Music Tech DIY
Topic: 100k input resistance... isn't
Replies: 89
Views: 2441

Re: 100k input resistance... isn't

In answer to this posting perhaps? Okay, so... maybe it should be considered bad style to use the output of an op amp internally when that op amp is also driving an output jack. We need to add an op amp just to drive the output jack, separate from the one that generates the internal signal. Now loo...
by mskala
Thu Nov 26, 2020 1:45 pm
Forum: Music Tech DIY
Topic: 100k input resistance... isn't
Replies: 89
Views: 2441

Re: 100k input resistance... isn't

How is that relevant to this thread?
by mskala
Tue Nov 24, 2020 6:30 pm
Forum: Music Tech DIY
Topic: Why is it fun to BUILD modular synthesizers?
Replies: 25
Views: 692

Re: Why is it fun to BUILD modular synthesizers?

Just taking the opportunity to drop the Lego harpsichord link: http://www.henrylim.org/Harpsichord.html
by mskala
Tue Nov 24, 2020 5:36 pm
Forum: Music Tech DIY
Topic: 100k input resistance... isn't
Replies: 89
Views: 2441

Re: 100k input resistance... isn't

I intended my post as a starting point so that we could hopefully work out a set of rules to cover as many situations as possible. I think - much as I said in the "voltage range" discussion - that it's a bad idea to try to simplify this down into a set of rules. At most, we can have guidelines of t...
by mskala
Tue Nov 24, 2020 5:15 pm
Forum: Music Tech DIY
Topic: 100k input resistance... isn't
Replies: 89
Views: 2441

Re: 100k input resistance... isn't

Sorry, I think I missed that you meant the first four circuits to be for module outputs and the last one to be for module inputs . Not the same situation, and some of the points I raised aren't relevant with that distinction. But others of the points I mentioned remain important, and this illustrate...
by mskala
Tue Nov 24, 2020 5:00 pm
Forum: Music Tech DIY
Topic: 100k input resistance... isn't
Replies: 89
Views: 2441

Re: 100k input resistance... isn't

So can we get a summary of best input and output practices for those times when we want to do it "right"? For example, does the following diagram from Dr. Sketch-n-Etch from the thread below represent the final word for outputs or is there a better way? Those topologies are more or less the ones we...
by mskala
Tue Nov 24, 2020 12:23 am
Forum: Music Tech DIY
Topic: What do folks mean by EXPONENTIAL thru-zero?
Replies: 4
Views: 239

Re: What do folks mean by EXPONENTIAL thru-zero?

My guess would be that the Zeropoint is doing an exponential minus an offset, something like f = exp(a*x+b) - c. The descriptions I was able to find with a quick Google search are pretty confusing. I don't think there is a "standard" meaning for this. As you say, exponential functions don't go negat...
by mskala
Mon Nov 23, 2020 4:10 pm
Forum: Music Tech DIY
Topic: PCB Manufacturing in Europe?
Replies: 22
Views: 518

Re: PCB Manufacturing in Europe?

There is pcb-pool (pcb-pool.com). I have not used them for PCBs, but the same company's "panel pool" service is good. You will pay a significant premium to have PCBs made in Europe in any case, and the higher base price for "made in Europe" will probably cost you more than the brokerage fees to impo...
by mskala
Mon Nov 23, 2020 9:52 am
Forum: Music Tech DIY
Topic: 100k input resistance... isn't
Replies: 89
Views: 2441

Re: 100k input resistance... isn't

Nobody seems to be mentioning the capacitance of patched cables in arbitrarily patched systems as a *good* reason to have *some* resistance outside the OPA output FB. Another reason to consider not putting the output jack (and therefore the output resistor) inside the feedback loop, is that when th...
by mskala
Sun Nov 22, 2020 4:36 pm
Forum: Music Tech DIY
Topic: 100k input resistance... isn't
Replies: 89
Views: 2441

Re: 100k input resistance... isn't

There are three different questions here: Is it bad that people say the input impedance is 100k, when it isn't always exactly 100k? Is it bad that people build modules such that the input impedance isn't always exactly 100k? Is 100k a bad value for the input impedance even if modules could always be...
by mskala
Sun Nov 22, 2020 11:22 am
Forum: Music Tech DIY
Topic: 100k input resistance... isn't
Replies: 89
Views: 2441

Re: 100k input resistance... isn't

I keep seeing so many posts where folks say such things as: A typical Eurorack input has an impedance of 100k. The more I see this, the more I realise this is such a dangerous assertion. Very rarely is this assertion actually correct, and so any discussions based on it are likely wrong from the out...
by mskala
Sun Nov 22, 2020 9:26 am
Forum: Eurorack Modules
Topic: Bipolar to unipolar conversion
Replies: 19
Views: 411

Re: Bipolar to unipolar conversion

Do you mean plug and play, sort of? The issue I can see is that variances in VCO outputs mean you won't always get them properly offset/attenuated. It might be interesting - and would make the module less trivial - to have it automatically adjust for varying input voltage ranges. That could be done...
by mskala
Sat Nov 21, 2020 2:14 pm
Forum: Music Tech DIY
Topic: AD633 vco through zero fm?
Replies: 4
Views: 200

Re: AD633 vco through zero fm?

Having no DC path for the bias current from the AD633 "Y" inputs seems like a mistake. Even though the chip is more complicated than just an op amp, those are effectively op amp inputs and they need DC paths just like any other op amp input. It's hard to think that adding rectification will help - u...

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