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Comments on What to check for when buying an electronic component or module?

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What to check for when buying an electronic component or module?

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How can I acquire electronic parts/items/modules and ensure that there is minimal risk of them being unsuitable for my project or design?

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  1. Any electronic component or module you buy for a project or design should have a data sheet. By data sheet I mean a portable document format (PDF or equivalent) like this: -

    Image alt text

  2. Do not assume that the product will be OK based on marketing/sales claims without researching the fine detail in the data sheet. This is why you need a data sheet so, do your homework and ensure that what you think you need is matched by the technical details in the data sheet. Make sure you have the latest data sheet (see 3 below).

  3. The data sheet is sometimes wrong so, if something appears not to make sense, double check that you have the latest issue of data sheet and, if in doubt about some parameter or other, you can always raise a question on this site to gain clarity.

  4. Earlier revision data sheets are usually available and so, if the manufacturer updates it, this can be traced back to the point where the change was made. Always save the data sheet in your design file when you use a new part. On the other hand, web-based specifications have no historical traceability and can lead to confusion and mistrust should things go wrong. This can make you appear stupid or careless and, won't provide the evidence that can cover you should there be customer dissatisfaction or legal problems.

  5. The manufacturer of the part should be reputable but, as we know, new part manufacturers entering the market may not have gained a significant reputation. So, this may be hard to establish and, you have to be cautious. A lot of confidence can be gained by reading and understanding the data sheet of the part.

  6. The supplier/shipper must be reputable for the type of goods they are handling (namely electronic parts) and, they should provide links to the manufacturer's data sheet (1). How do you know that some unmentionable supplier hasn't mishandled the goods and damaged them? I'm thinking ESD and water damage here but, there are probably other ways "unseen" damage can occur.

  7. Watch out for fake parts - if the price seems too good to be true then maybe consider that the parts might be fake or possibly failed items underhandedly acquired by some disreputable supplier

  8. Decide what you need to buy - don't assume that any old resistor, capacitor, transistor or op-amp is going to work - think about what your final expectations are and, where things can go wrong (such as drift or basic output inaccuracies). You can't expect a supplier to be held responsible for you choosing a part that you haven't thought through sufficiently. This is what design is about - it's not about guessing that this or that will do so, do your homework (or pay the cost).

  9. If you buy from a source selling unbranded goods you are taking a risk and, quite possibly, you will pay more (due to you wasting your own time) in the longer run so, how much do you value your time?

I'll probably think of a few more things to add as time passes by.

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General comments (13 comments)
General comments
manassehkatz‭ wrote almost 4 years ago · edited almost 4 years ago

PDF icon means nothing here. Arguably anyone browsing the internet for help on pretty much anything should know what a PDF is (and if not, they can google it). Far better would be to include links to a couple of sample real-world data sheets - perhaps one old (e.g., a 74xx series chip) and one new (an Intel i5 CPU or similar). That way people not familiar with data sheets can click on the links and see what you're talking about.

Andy aka‭ wrote almost 4 years ago

Have you ever noticed that when going to a component website that the data sheet link is usually a PDF icon. Hence why I deposited the PDF icon in the answer so, I presume that when you say "PDF icon means nothing here" you must mean something else. And no, I disagree that "anything" (presumably you mean anyone) should know what one is.

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Andy aka‭ wrote almost 4 years ago · edited almost 4 years ago

@manassehkatz I rejected your modification because clearly we don't agree. If I can't use the PDF logo in the answer for legal reasons then that's fine - I shall remove it and find another way of expressing it. But, seriously, there are a vast number of budding engineers and hobbyists out there who haven't a clue about data sheets and you are missing the main point in my opinion.

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Mithrandir24601‭ wrote almost 4 years ago

There are a couple of things that I feel would be useful additions to this answer. You say that "Any electronic component or module you buy for a project or design should have a data sheet", but how (hypothetically) would I go about finding/getting this datasheet? Similarly, how do I "Make sure [I] have the latest data sheet"? How do you know if a manufacturer is reputable?

Andy aka‭ wrote almost 4 years ago · edited almost 4 years ago

If you can't find a data sheet then it's likely because there isn't one. Hence don't use the part. You find reputable sources based on searching around and looking for good electronic parts suppliers like Farnell, RS, Digikey, Mouser (for instance). And, importantly, if you target a part that you might want to use, the part manufacturer will list reputable distributors that can sell you this part.

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Andy aka‭ wrote almost 4 years ago

I think you guys are just not thinking this through or just trying to be insincere. If you choose a component then you have looked on the web to find it and, where you find it, you find the data sheet. If the data sheet isn't there you don't use it (or persevere to find one). There is no HOLY repository of data sheets - if you think you want to use component X then you want to use it because it seems to fit the bill - that is where the data sheet is now use your heads guys and stop being idiots.

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Andy aka‭ wrote almost 4 years ago · edited almost 4 years ago

Exactly, so you don't buy from Amazon and you don't buy from amazon because they are not a reputable dealer (as of 2020). They are not a reputable dealer because they can't be trusted to deal in chips and electronic components. That has to be the conclusion. So, you take a trip to Intel and look to see who they recommend you buy from or who their local distributors are. It's not rocket science.

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manassehkatz‭ wrote almost 4 years ago

In other words, give them the information they need. FYI, I saw your answer on https://diy.stackexchange.com/questions/195628/understanding-the-markings-on-a-fuse - very nice (I don't hang around EE much but I read everything on DIY).

Andy aka‭ wrote almost 4 years ago

I can't go around putting "don't buy from amazon or ebay or aliexpress or bang-good" because they may just begin to hit the mark in terms of being acceptable dealers in EE components. They are not today and show no signs of being reputable for Pro EEs. But let's say I did make a list then what about all the other unreputable sources - where does the list end and who manages the list. I've tried to make this answer cover the eventualities without naming names.

Andy aka‭ wrote almost 4 years ago · edited almost 4 years ago

which is why they are coming to Codidact to see the canonical answer of "how to buy components" - then it's not this answer or question. This question and answer is not that directly and it's done this way so as not to name names specifically. Point 6 and point 9 in the answer covers that as far as I reasonably would want to go.

Lundin‭ wrote almost 4 years ago

Another important thing to consider: part status. Does the manufacturer list this as highly recommended or active? If not, stay clear of it. If you are considered an important-enough customer, you can also poke a large distributor (Arrow, Avnet etc) and ask them if this part is a "high runner" or if it's just something bought by one single, big company.

Lundin‭ wrote almost 4 years ago

Yet another trick: poke the manufacturer's tech support early on, to see if they are useful or if they hate to have customers. Similarly, can you get samples for the part or is that mission impossible unless you buy MOQ 10k?

Russell McMahon‭ wrote over 3 years ago

And even here you get downvotes on useful; answers :-).