Reverse voltage protection on the Arduino nano

Hi Ron @zander,

  I mentioned the possibility that someone might have a 'fake', not as a 'professional' point of quality, legality, etc. but simply, because:

If, you are relying on a board to wired up in a certain way ... then if it's a 'fake', it might be wired differently, with components changed or missing, and so on.

And since I don't know the consequences of the expected 'protection' not working as expected for the OP, I thought it was responsible to make sure they were aware of the possibility, so they could take any precautions they felt necessary.

I totally accept that most of us will take things as they come, assuming a fair degree of trust, but that is not always appropriate.

Best wishes, Dave

Hi Ron @zander,

 The board I had to decipher was covered in thick black solder resist, making visual tracking of traces impossible.

  Hence, I used a continuity buzzer approach ...

Best wishes, Dave

@dronebot-workshop @zander @davee

 It is an official board.

Thank you all so much for the help.

Josiah

@davee Just as long as you mention that it is extremely unlikely.

The problem is I do not know of any reliable test to determine not only a fake board, but now that you raised the possibility a fake AND dangerous board.

Since most products today come from places that do not respect IP, safety regulations or quality in general, then the same concerns apply to your hairdryer (I don't need one), electric toothbrush, impact driver, drill, circular saw, toaster, kettle etc etc.

Given your concern, what steps do you take to ensure you are safe?

@davee You have more time than me.

Hi Ron @zander,

  Obviously, in the commercial world, there are lots of manufacturers making products that can have lethal consequences if they fail in certain ways, and if they start shipping products with compromised components, then the risk of those potential failures is likely to become much higher. A major part of building and designing a product that is safety critical includes starting with the 'mindset' that every constituent component of that product will suffer a failure, and trying to find a means of removing or reducing a bad consequence if it fails.

Obviously, if the motor on a washing machine quietly stops working, without being hazardous, that is not a safety issue, although if many customers are affected, the reputation and financial security of the company may be at risk.

By contrast, a major car manufacturer producing vehicles with a braking system that completely fails without warning, will soon have more than warranty claims to worry about. Thus, since maybe the mid 1960s in the UK, cars have split hydraulic systems for the braking system, so that if one side suffers a massive leak, at least two of the 4 wheels will still have an effective braking capability.

This side of safety is usually in the hands of large companies, rather than individuals. If I was working in such a position, then I would expect the company to be employing staff to carefully check where they are procuring parts from, as well as the company having policies and systems to minimise the chance that designs, working practices and so on, do not introduce unnecessary risks, and the overall design culture would include analysis to determine the risks of failure and the steps taken to ameliorate the residual failure risk, given that no complex machine is likely to be fault-free forever.

As a consumer, who has retired, for 'house and transport', I tend to buy equipment that I hope will be reliable, and in many cases that I will be able to fix it, if it breaks down. Clearly, I am not in position to check out the supply chain for the constituent parts of a washing machine! But I will probably look to something like the Bosch/Neff/Siemens white goods manufacturing group, in the hope they are so scared of the consequences of producing fundamentally unsafe equipment, that they will do their job. Of course, this is not an infallible approach, but I see it as the best I can do.

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Stuff like microcontroller development boards, which are only for my amusement, I am much less concerned about. The faulty ESP32 board only I mentioned before, probably cost around £4, and the obvious place for it was the bin, but I persevered with it as a way of becoming more familiar with that particular type of product. I found its design was based on one of the Espressif products, but the USB chip was different. The particular chip was obsolete, with regard to new designs, but still documented, etc. The USB chip was not actually the problem, but I needed to figure out its wiring, etc. because it provided the drive to the part that had actually failed. To make life more interesting, the failed device had no markings, so I had to identify that, at least to the point of identifying a replacement part that would do the job.

Hence, I spent quite a few days, fixing a board, which was a 'dubious' clone of another board, with a part that had its markings removed, and whose total 'value' at best, was about the same as coffee in a shop!! However, I think it was 'educational', and I wasn't likely to be physically harmed by it.

Which is probably a long way of saying, that I do my best to avoid 'fakes' and 'clones' for washing my clothes, but I am more likely to treat small microcontroller boards as a challenge, providing they are not likely to endanger my health or well-being.

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I tend to be a bit more cautious when advising others, because I don't know the consequences. In some cases, the consequences might be a physical threat to life, but more commonly the person is trying to achieve something, and as I am not in the room, I can't intervene when something 'unexpected' or 'unusual' happens, so the best I can do is to try to foresee such things, and warn them. That is, I try to minimise disappointment.

Furthermore, at least some of the questioners are relatively new to the subject, may be financially constrained, and may easily be submerged by several problems at once. Hence, I try to be cautious to minimise the chance that they will suffer losses from (expensive) damaged components, etc. If I think they are likely to dong something dangerous, I also comment. Of course, I can't foresee all possible eventualities, but I hope to help in at some cases.

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A long diatribe but hopefully useful in some way.

Best wishes, Dave