[makerboardzz]

Cool - it looks like a well-designed board, although the timing is a bit unfortunate with the ESP32-S2 emerging as an ESP8266 replacement with USB.

A few questions:

* Should the relay have some sort of isolation, like an optocoupler?

* Is it FCC-certified?

* Like other people asked, any information on how the antenna was designed?

I like the old-school dome LEDs. And it's cool to see another project with a CH340 USB/USART bridge, even if they wouldn't need it with an ESP32-S2.

[LeifCarrotson]

Regarding your first point, the relay has 2,000V of coil-to-contact isolation:

https://omronfs.omron.com/en_US/ecb/products/pdf/en-g5le.pdf

Though it does look like the clearance/creepage distances on the PCB to the low-voltage ground plane are not any wider than 2mm or so, which is acceptable for 120VAC, but not acceptable for 240VAC per IPC9592.

I wouldn't worry about sticking this in an enclosure and using it to turn a light on and off, but I wouldn't want to be handling it while it was live, either!

Regarding FCC/UL certification, a product is exempt from FCC certification requirements if it's "A digital device used exclusively as industrial, commercial, or medical test equipment", which most development boards are. I've got some dev boards from Microchip on my bench right now which aren't FCC or UL listed, either.

[tripletao]

A digital device is defined as:

> (k) Digital device. (Previously defined as a computing device). An unintentional radiator (device or system) that generates and uses timing signals or pulses at a rate in excess of 9,000 pulses (cycles) per second and uses digital techniques; ...

https://www.govinfo.gov/content/pkg/CFR-2009-title47-vol1/pd...

This has Wi-Fi, so it's an intentional radiator, so it's not a digital device. I believe this product would be technically noncompliant if not certified, though lots of stuff like this gets sold and I've never heard of any enforcement action.

Their best counterargument would be that it's a component and not a self-contained product. That seems true for many dev boards but not particularly true for this one. Since the practical risk of interference is extremely low, I'd guess the FCC is happy to leave this grey for now.

[R0b0t1]

Test and measurement supersedes intentional emission. If it were the other way no development boards would get sold, especially necessary things like low volume engineering samples. Should a one-off need certification before it can be transferred to the company that contracted the work to build it? No.

If you have never sought certification know that it is quite expensive.

What seems to matter the most is if anyone actually notices interference, and if they do how widely the device ended up being sold. If a test and measure product starts making it into everybody's house eyebrows will be raised.

If you misuse a test and measurement device and generate interference it is typically on you.

[tripletao]

> Test and measurement supersedes intentional emission.

On what authority are you claiming this? The language LeifCarrotson quoted refers only to digital devices, and the language I quoted above says plainly that a digital device must be an unintentional radiator.

To be clear, I believe selling their dev board is fine, but it's fine in the same way that driving 60 mph in a 55 zone is fine. Anyone selling an intentional radiator dev board that could reasonably be considered to be a complete device in itself is taking a small risk of FCC action, especially if (as here) they're pushing the limits of "dev board". Note that the Raspberry Pi developers do seem to get certs.

https://www.raspberrypi.org/documentation/hardware/raspberry...

[R0b0t1]

On what authority are you claiming otherwise?

My opinion comes from experience and getting things certified but also common sense and observing enforcement patterns (the latter of which is most important until they overstep and get challenged).

Go back to my example: Does a one-off product need to be certified to be transferred to the people that paid for it? Keep in mind, best case, this will add a roughly >$10k fixed cost to the sticker price.

It's a general principle in common law that the law makes sense. The popular, sophomoric, and extremely conservative interpretation of the FCC rules makes no sense by way of being extremely costly for no discernible benefit, either to the seller, the buyer, or the economy at large.

[tripletao]

I am claiming this on the authority of the text of the regulations. The USA is a nation of laws, and those regulations have the power of law. If it came to that, a judge isn't going to disregard them just because you think they're too expensive. If you think otherwise, can you provide case law to support your view?

By law, that one-off intentional radiator absolutely does need to be certified. The FCC's enforcement priorities will be different depending whether that product is a little 2.4 GHz radio or a television transmitter, but their enforcement discretion doesn't change the law. Anyone who wants to be compliant needs to pay for the testing (or use a certified module, which is often easy and cheap; I've done that several times myself).

Lots of people disregard lots of laws because they're too expensive to comply with. Most of them get away with it, and a few of them get nasty surprises. I believe that I've given both the correct legal advice and a correct description of typical (not fully legal) practice. It's not helpful to conflate the two.

[antoniuschan99]

If it’s sold as a kit(eg. Devboard) or battery powered it doesn’t need to be certified. You also can get pre-certified boards, the wroom-02 being the pre-certified esp8266.

[R0b0t1]

I've seen certified development boards also, but what most don't realize is you can't combine certified parts to make a certified product. So depending on your product there is literally no benefit to getting it certified.

There are things that are battery powered that need to be certified and things that are not kits that don't need to be, though, so I'm not sure I can agree with that wording.

[tripletao]

I think battery-powered unintentional radiators can sometimes avoid testing, but battery-powered intentional radiators definitely don't. The statement about kits is also wrong, per pdabbadabba's comment below.

An intentional radiator module can get a module certification. In that case the final system still needs verification (the same kind of testing that an unintentional radiator gets), but doesn't need certification. When you see a label on the outer device that says "Contains FCC ID XXX-XXXX", that's the module's ID.

https://apps.fcc.gov/oetcf/kdb/forms/FTSSearchResultPage.cfm...

[tripletao]

And I'm responding again to note that I think I interpreted "kit" wrong. I was thinking "kit" as in § 15.23, which gives an exemption for stuff you build yourself but not stuff you build from kits.

But 47 CFR § 2.803 gives an exemption for "evaluation kits". I don't think that clearly covers boards used primarily as single-board computers (and not genuinely for evaluation), and I'd guess that's why the Pi developers got certs for their boards. I believe it's the best argument that this board wouldn't need certification (or verification), though.

[conk]

I don't see any benefit in using an optocoupler. Using a transistor with flyback diode for protection is acceptable. Both the relay and ESP8266 are powered from the same 5V source, adding an optocoupler is not really isolating anything.

[elcritch]

Sometimes it’s easier to deal with a combined part than two parts. It can reduce assembly costs for small volumes, or if the person doing the design is just familiar with the opto.

[pdabbadabba]

> * Is it FCC-certified?

It would certainly appear to lack the FCC ID label/marking it is required to have if it is FCC certified. So probably not. Thus, it also appears doubtful whether it can legally be marketed or sold in the U.S.

[simcop2387]

IANAL, But I think device as-is can likely be sold and marketed perfectly fine. Test-kit and dev-kit stuff is regulated a bit differently under the assumption that it's not going to be in mass use, and also that it's likely going to be used to develop another product that will get the fcc certification.

https://emcfastpass.com/fcc-rules-kits-subassemblies/

[pdabbadabba]

The link you provided appears to say the opposite about kits:

"Based on the definition above, it looks clear that non-authorized kits that are intended to form a complete product when fully constructed are technically not legally permitted to be sold in the US. That is because if you are marketing and selling a kit to an end user, which the user will then build into a full product, there is no reason to suspect that the normal rules would not apply."

The subassembly rules could work, if they apply, but I don't see how this product fits the definition of a sub-assembly:

"No authorization is required for a peripheral device or a subassembly that is sold to an equipment manufacturer for further fabrication."

In fact, I think it's a stretch to say that any of these test-kit, dev equipment, or subassembly rules apply. This basically strikes me as being marketed as a consumer product -- albeit a product for very tech savvy consumers.

[sokoloff]

I don’t believe that dev board is a complete kit by the meaning of that rule.

Certainly there is ample precedent for other dev boards (intentional and unintentional radiators) being sold without certification.

[iancmceachern]

Like everything on this site:

https://www.tindie.com

[conk]

A search for "Malouf" on the FCC registration website provided no matches. Most likely this product is not registered.

In addition, this product lacks a CE mark and has no UL/FM/CSA listing. I'm curious what creepage/clearance requirements were factor into the design. This product is potentially dangerous if the relay is switching line voltage.

[peterburkimsher]

This is the exact reason why I didn't see through my plan to build and sell the EspUSB (a very small ESP board that fits inside a USB-A port).

I got 3 units built for myself by PCBWay at a cost of $77. I got quotes of ~$500 for 100 units from Elecrow and Makerfabs, but didn't know what to do with the other 90.

Although I really want this great little gadget to be easily available, I can't afford $10,000 for FCC certification, and therefore I have no solution.

If anybody wants more details, email [e-mail] and we can chat about it on there.

[alacombe]

> I can't afford $10,000 for FCC certification, and therefore I have no solution.

That's not how it work. You start by selling them, prove the concept, and when you have the money, you sort out certifications & whatsnot.

You won't become a unicorn if you think about doing everything _by_the_book_ from day one.

[peterburkimsher]

I have enough legal trouble just trying to get a work visa. I'd rather not risk criminal charges, deportation, or worse for a hobby project.

[iancmceachern]

I wonder how the folks that sell on Tindie get around this... https://www.tindie.com/

[tesseract]

There are various exemptions for subassemblies and other non-end-user products. Those may not always apply. However, in practice, a product that's sold in small quantities and does not in fact emit egregious electromagnetic interference is unlikely to attract enforcement attention. So a fair bit of skirting of the rules does go on.

[peterburkimsher]

Based on the PAL project and WiFi capability, I think the ESP8266 does emit electromagnetic radiation. Whether it's interference or a feature depends on your perspective.

[antoniuschan99]

What about using a pre-certified module (eg. Wroom-02 or wroom32)

[peterburkimsher]

Because it won't fit inside a USB port any more.

[Gibbon1]

One way to deal with high voltage is to use an external hockey puck solid state relay. Keeps the high voltage off the PCB and you don't have the kick from the relay coil finding it's way into the digital logic.

[ohazi]

A decent heuristic for whether or not a wireless module has been FCC certified is whether or not the RF components are under a metal shield:

If it doesn't have a shield, it's almost certainly not FCC certified.

If it does, it's more likely to be certified.