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What I learned selling 2,500 MIDI recorders: Hardware is not so hard

chipweinberger.com

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Re: What I learned selling 2,500 MIDI recorders: Hardware is not so hard

#71

Post by iamflimflam1 »

chipweinberger wrote: post #16
nippoo wrote: post #14

How did you navigate the world of compliance testing and certification, with all the different countries involved (FCC, UL, etc). Are there any markets you've decided not to sell to as they're not worth the paperwork?

I chose to do FCC only and CE self-certify. If you use pre-certified radios it's not as expensive as you think. $5K should be plenty if you ask around. Just make sure you design your board so you actually pass, and don't let the labs over-sell you. They'll try to! 99.99% of cheap Chinese products you buy on Amazon don't actually have this testing done at all. So by doing any testing you're already way above them.

I wrote a bit about this in CrowdSupply write up - https://www.atomic14.com/2025/07/21/crowd-funding-retro

CE is all about self certification. The lab testing gives you the confidence to do this.

It can be expensive - but Chinese test labs are very affordable and do a really professional job.

There is now quite a good EU based service - https://early.smander.com/ I used them to get some advice early on (disclaimer, I know the founder).

Re: What I learned selling 2,500 MIDI recorders: Hardware is not so hard

#72

Post by michaelrpeskin »

dgellow wrote: post #60
embedding-shape wrote: post #37

Earlier quoted context omitted.

> now that LLMs removed most of the fun of programming Never understood this, was the "most of the fun of programming" the literal typing for you? For me it was about solving problems and building things, and I get to do that more now than before, and without all the literal typing.

I reject the idea that programming is „just typing“, so we are very unlikely to understand each others. Writing the code and thinking about the exact logic you want to apply and all its implications are part of the same problem solving process in my mind. You can for sure plan things at a different layer of abstraction but putting things together in code is a very satisfying and IMHO is the actual building part of th…

Rather than "managerial" I tend to view it as more "professorial". Maybe it's my academic training (but I got out before I became a professor), but I tend to like to think about my problems in terms of abstractions and invariants and common ways to represent things. I just now describe them in English rather than code. But I do find that LLMs do a much better job the more clearly and completely I express what's in my head. I get that same satisfaction that you mention, but now it's when the LLM does what I want on the first try rather than fighting with it all day.

In the past when my junior engineers were fighting with a bug all week, I always told them the dopamine hit of solving the bug is what keeps you coming back to work for 20 years. Half joking, but the dopamine hit of from the satisfaction getting complex working software in a weekend is like crack to me, we'll see how that plays out long term :)

Re: What I learned selling 2,500 MIDI recorders: Hardware is not so hard

#74

Post by chipweinberger »

alance wrote: post #58

Ok are you riding with two huge boxes containing all your work on an electric unicycle and I guess the hi-vis top means you're headed into traffic and the box-cords seem to be balancing at the halfway point of the boxes and this is too much anxiety for me. But hey, glad you optimized for minimalism on the PCB ♡

Ahah good eye. It was only 4 blocks down the road! I too was surprised by how well a single cord worked to balance the 45lb boxes.

Re: What I learned selling 2,500 MIDI recorders: Hardware is not so hard

#76

Post by iamflimflam1 »

msandford wrote: post #45
chipweinberger wrote: post #2

I'll be sticking around in the comments so feel free to ask questions. AMA!

I recognize the "esp32 perched on top of a circuit board" from the picture. I've got a couple of those at my house right now, I'm on the second version of one board and the third of another. I think I'm going down a very similar road for a different product. Would you be willing to some paid advising? I'm an EE so I don't need hand-holding on the actual boards or programming, really just looking for more information…

I can/try to give you some advice if you need - email is in my bio. I did a semi successful CrowdSupply project based around the ESP32S3.

Re: What I learned selling 2,500 MIDI recorders: Hardware is not so hard

#77

Post by raphman »

chipweinberger wrote: post #2

I'll be sticking around in the comments so feel free to ask questions. AMA!

The website gives a very nice and captivating intro to the device.

But why do you spell MIDI in lowercase there?

> plugs into your piano via midi

Re: What I learned selling 2,500 MIDI recorders: Hardware is not so hard

#78

Post by NBJack »

Hackbraten wrote: post #54
swiftcoder wrote: post #17

Earlier quoted context omitted.

Almost all commercial devices need a unique ID, private key, etc burned in on the production line. For a big enough production run, you'd likely ship an HSM to the factory

> For a big enough production run, you'd likely ship an HSM to the factory I figure that the factory is exactly the adversary in the whole threat model? So why give them the keys to the castle so they can moonlight their own genuine batch?

A few ways, if I understand them correctly. On-site people you employ (if you can afford it) auditing the process, connectivity to the HSM to record every key assigned (makes it easy to trace duplicated keys to their origin), and ideally assigning these keys at the very last possible step after the rest is assembled (to minimize 'defective' parts wandering off and being assembled elsewhere).

Re: What I learned selling 2,500 MIDI recorders: Hardware is not so hard

#80

Post by realo »

embedding-shape wrote: post #49
realo wrote: post #44

Earlier quoted context omitted.

I understand what he means. Software can be about the beauty in an algorithm, the elegance of an implementation. This is very similar to the type of beauty and elegance one finds in Mathematics. For many, writing software is more about crafting a beautiful design than typing lines of code. Getting things done is not about crafting, though (although crafting IS about getting something done). Thus the big clash when su…

> For many, writing software is more about crafting a beautiful design than typing lines of code. Yes, I count myself as one of these people, hence not caring much about the actual typing part. > Getting things done is not about crafting, though (although crafting IS about getting something done). I'd say it is, I like getting things done, hence I care about high quality code and proper design/architecture of the sof…

I agree, but would add that maintability is , and always has been , a hallmark of quality software.

LLM spaghetti code is unacceptable.

LLM code with a complex pile of overlayed abstractions only someone with a PhD in Software Engineering can debug or even get to compile years later when public APIs change is also unacceptable.

Same thing with human engineered software abstractions.

But I get you. Human directed AI is the only way to go ... for now ...

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