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Making products for sale

19 March 2024 at 9:25 am

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​About half a year ago, I found a new type of radar that solves a problem I’ve faced on several occasions: to reliably detect the presence of a person. A PIR sensor can detect motion and change, but not a person standing still. This new sensor looked really solid, but I couldn’t find anyone making products with it so an idea was born.

​The last years I’ve done several projects using the classic red phone booths we have in Norway. They’re now turned into micro-libraries and my current project is to create and install IoT hardware that allow you to listen to audio books using the old phones in these booths. The project is moving along nicely, but the customer wanted the phone to ring when you entered the phone booth. This you could easily do with a PIR sensor, but they then wanted to detect for how long the user was engaging with the audio experience. To know this for certain, I spent time researching millimeter radar sensors and I found that these can solve several problems in exhibition design. My idea was now to turn this sensor into a product that had two relays that would open/close based on presence.

Those that do Exhibition Design are not always the most adept at programming. They typically want to buy something that “just works”, so my idea was to make a product that is super easy to use, easy to setup and debug and is flexible enough to solve many tasks. Designing Electronics is my daytime job and over the years I’ve become quite good at it. This is to me the least complicated part of making a product and until you make a product yourself, it’s quick to think that this is all that is needed.

Making the device

After making sure that the electronics could do the job, you need to package it. I don’t mean in terms of wrapping, but rather in terms of finding a good enclosure that has the right size and features. It must be easy to mount anywhere. It needs to have the required openings in the enclosure. It must not disturb the radar sensing too much. It must allow simple debugging when setting the device up. It must look reasonably good, but it’s not made to neccesarily be displayed. After searching online, I finally found a good enclosure that both has a DIN rail mount as well as two screw holes.

The enclosure had two openings that I could use. The first would be where you plug in power, connect wires to the relays and adjust the sensitivity. The other would be covered up by a 3D printed semi-transparent piece of plastic that diffused the light from the RGB LEDs used for setup and debugging. After a couple iterations on the electronics using the ESP32-S3, I realised that this product didn’t need such a powerful chip, so I moved to the smaller ESP32-C3. This allowed for adding more LEDs to increase the visibility when debugging. I also figured that the user might need some options, so I added a hardware button. I then fleshed out the firmware and while this was going on, I also sold the first few products to local firms.

So at this point, I have the product ready. Now it’s just to ship it off, right? Not quite.

Beyond the device itself

To actually sell the device, I need a few more things:

  • A USB Type C cable to power the device
  • A screwdriver to adjust the device
  • Packaging that in addition to the device, must hold the USB cable and screwdriver
  • Approvals
  • Instructions on how to use the device
  • Support services (email, faq)
  • Webshop, shipping & returns

Let’s start with the last one of these. The price of sending packages in Norway is so prohibitively expensive that you literally cannot compete. Also, I’d like to leave the shipping to someone that already knows how to do that. Shipping internationally is a complex task and you can easily burn through a lot of money by just filling out forms incorrectly. If I can reach the american market easily that’s even better, so I’ll do the shipping & selling via Amazon. That’ll give me one day shipping and it’ll ensure that I don’t screw up on logistics & customs. Amazon can also handle returns.

Then I have to change maketronics.no into more than just a business card (as it’s been up until now). It needs to have a good product presentation with links to the Amazon store. It needs instructions on setting up and using the product as well as a way for customers to reach out if they have problems. When I eventually see what problems the customers have, I’ll gather these into an FAQ. I’ll probably also have to make videos that show how the device works.

And then I’ll need to pack the device so it can withstand shipping. The packaging must have room for the complementary USB cable and screwdriver. It must have a decent looking design so that it could be put on a shelf. It needs printed specifications on the box as well as a bar code. Not just any bar code. It needs to be registered to your company and it must point to that specific product. If you don’t have this in place, Amazon won’t let you sell it. In terms of approvals, the microcontroller and radar are pre-approved by FCC so that should be sufficient, right?


Not quite. Some Youtubers will tell you that any product using a pre-certified module can be sent straight to market. Others even say that if you only sell a small amount, you don't need any certification. This is both incorrect. You as a product creator have to verify that the way you put your product together did not change the emissions as compared to the precertified modules. In many cases, this is just a $500 job, but if your product is using 24Ghz radar, this is going to be very expensive (close to $10k). I'm currently working on solving this without breaking the bank or failing the test (which would require another $10k for retesting). The current plan is to find a testing fascility that can just confirm that the EMC is not changed and that the pre-certification is thus valid. Odds of this succeeding are pretty good since the module is already certified without an enclosure. My plastic enclosure will dampen the radio signal a little bit and that makes it more likely to pass.

Then there is the issue of RoHS regulations. You basically have to make sure the device is lead free and does not contain any other hazardous metals. This part is easy, but requires that you specify components and PCB to follow this. In Europe, you actively have to ask for Lead solder and components with hazardous contents. In China, you have to carefully specify that you only want leadfree finish for RoHS compliance. These two things will make it possible to sell your product in the US, but not in EU. For the EU, you'll need a CE Certification and combined with emissions testing, this is about $10k. So even before you know if your product is successful or not, you'll have lots of upfront costs. So the current plan is US first with verification testing and then EU with full certification testing. I'm currently also doing long term product testing both indoors and outdoors to make sure the device is solid.

Selling on Amazon

So now you have a working prototype or maybe even a small series produced. How do you get it on Amazon? This part isn't all that difficult, but it all adds up and will take quite a bit of time. The first time I tried to sign up, the forms used to sign up just didn't work. There was 50+ Javascript errors in the inspector, so I guessed they deployed something without testing and tried again the next day. That worked a lot better. I clicked through wizard after wizard to configure and setup things. One thing to keep in mind - some of these things (such as settung up bank transfers and verifying that you are the owner of your own brand) can take up to a day for Amazon to confirm.

To publish a product, you'll need the sales pitch and other text as well as pictures. Not just any pictures though. You need to provide pictures with a nice, clean white background showing just the product and nothing more. I now have an account set up and 3 products added, but I can no longer add the pictures needed. For that, I'll likely have to wait for a human (or AI) to look at what I sent in and to tell me that I'll need better pictures. There is no way for me to say “wait! I now know that you won't like the pictures I sent”. I have to wait for them to decline the listing and then I must likely go through the process again. Overall, I'm happy thus far but it seems that I'm bound to hit an AI bot at some point since lots of the Amazon customer service is automated.

Are we there yet?

With all this in place - it should in theory be just to create, test, prepare, package and send off to Amazon. That is - unless something pops up (as is very likely). And then there’s marketing, making videos of Use Cases ensuring that you have all the parts needed for the next bach of the products, making product variants (colors, designs) to target different markets and so much more.