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Topic: Arduino Power Supplies (Read 3182 times) previous topic - next topic

Constantin

#15
Dec 08, 2012, 01:08 pm Last Edit: Dec 08, 2012, 01:13 pm by Constantin Reason: 1
All of the mains-connected power supplies I buy feature multiple approvals. But in an era where such approvals are easy to fake, approvals in themselves are like the TSA - ie security theater - that can lead to a false sense of security.  

Having an approval sticker/stamp/whatever by itself on a product is pretty meaningless - you have to combine a allegedly good power supply with a known good reseller to be reasonably sure that you're getting the paid-for goods you desired.

In my example above, have a look at the myriad of hosted resellers on amazon, eBay, and similar web sites selling goods that impersonate well-known products.  When I had to buy additional power supplies for my Mac laptop and apple phones, I went to OWC for that reason.

Similarly, I prefer buying my power supplies and similar gear from the likes of adafruit, digikey, etc for the simple reason that the probability of paying for the real goods is higher on those sites than eBay for example.

Bottom line is that the supply chains are getting inundated with products that look like the real deal down to the point where you'd have to undo the ultrasonic welds and peek inside the product to see if it contains all the design features asked for by safety agencies. So even sourcing from adafruit or digikey may eventually lead to a dud - I just expect that probability to be lower.

oric_dan

I thought maybe Constantin from The Central Republic of Cantabrigia was from somewhere
in central Asia, and was buying goods shipped in from Moscow. "Da Comrade! Of course
is approvaled".

I agree with you, better to buy something with an approval sticker through digikey or similar
than to save a few dollars and buy through ebay from a noname company in CN. At least if
it blows up your house, digikey has someone to talk to about it.

Constantin

#17
Dec 08, 2012, 08:08 pm Last Edit: Dec 08, 2012, 08:14 pm by Constantin Reason: 1
Easy now. Just because some goods from Asia do not meet your standards does not mean that all products from there are junk. As with many things in life, the quality of a product has less to do with its point if origin than the care and dedication of its maker. Making jokes about pronunciation may be funny to you, it is not wise IMO.

retrolefty

#18
Dec 08, 2012, 08:22 pm Last Edit: Dec 08, 2012, 08:25 pm by retrolefty Reason: 1

Easy now. Just because some goods from Asia do not meet your standards does not mean that all products from there are junk. As with many things in life, the quality of a product has less to do with its point if origin than the care and dedication of its maker. Making jokes about pronunciation may be funny to you, it is not wise IMO.



I agree, I've probably made at least a fifty purchases on E-bay with Asian electronic parts and module suppliers and have yet to be disappointed with the quality of any of the items I've received. Maybe it's because I only buy if I can see a clear picture and all the specifications and or drawings in the e-bay ad that I will need to use the device, as I will say there is hardly ever any documentation sent other then what was in the E-bay ad. It's been my experience that the Asian sellers are very protective of their positive feedback ratings and I have had no problem getting them twice to send the correct item after receiving something different twice, they even said keep the original wrong items, bulk capacitor assortment and bulk resistor assortment both times, I order through hole and they sent SMD packs.

Lefty


oric_dan

Quote
Easy now. Just because some goods from Asia do not meet your standards does not mean that all products from there are junk. As with many things in life, the quality of a product has less to do with its point if origin than the care and dedication of its maker.  


"My" standards have nothing to do with it. You seem to have missed the part where I said
Quote
I agree with you, better to buy something with an approval sticker through digikey or similar
than to save a few dollars and buy through ebay from a noname company in CN. At least if
it blows up your house, digikey has someone to talk to about it.


You're free to buy "unapproved" products from noname CN companies all you like, and plug into
your power mains all you like. It's your house, after all. This is all a very nice object lesson for
noobees.

Quote
Making jokes about pronunciation may be funny to you, it is not wise IMO.


It's ok, when it's about the former USSR.

Docedison

And the purpose of this diatribe is??
In 50 years of fiddling with wires and tubes then transistors.......
In all that time I don't believe I've EVER seen a catastrophe occur due to a part sold without a "Correct Sticker" and as to " digikey" has someone to talk to about it.
I doubt that anyone in CN would claim any responsibility, Period.
I guess that ultimately YOU are responsible for anything connected to the mains and if YOU haven't taken the proper recommended precautions then you have truly earned the fruit of your labor... Insurance is cheap, infrared detectors are cheaper and much better if used to monitor your 'hot" area's.
Seriously the major issues with poor quality devices are generally apparent from the onset of use and continued use is it's own reward.

Bob
--> WA7EMS <--
"The solution of every problem is another problem." -Johann Wolfgang von Goethe
I do answer technical questions PM'd to me with whatever is in my clipboard

westfw

I am curious how the various US "fronts" are getting away with things.  If I order "direct from China" via eBay, I expect to need to do some "due diligence" to make sure that what I got was what I was expecting.  But it's a bit shocking to get one of those fake and unsafe "Apple compatible USB charger" modules from "All4Cellular.com", with the UL symbol blacked out; I thought companies actually doing business as part of the US (collecting state sales tax and everything) operated under some restrictions WRT selling random mains-powered electronics...

oric_dan

Quote
In all that time I don't believe I've EVER seen a catastrophe occur due to a part sold without a "Correct Sticker"


This whole thing is a little belabored, I guess. OTOH, I doubt in 50 years, you've actually
plugged very many non-stickered devices into your power mains either. Until now. I'll bet
you don't even have many in your house from past years. Would be interesting to know.

Docedison

I actually use what I make and with one exception where I didn't have the proper sized fuse and did smoke a power transformer due to a shorted diode because I didn't utilize the proper transient protection... I've Never had a problem.
I've built a few power supplies and re-purposed many different pieces of electronics equipment for a long time and there are some things that are necessary, one is adequately protecting the place where you live. It's called "Due Diligence" Or CYA.
As to improper devices being sold from the Asian vendors...
That unfortunately is a serious issue with little chance for a solution
If it doesn't look or feel right I just chuck it... if it has no other value and mark that vendor off my list. 
Life is too short to get caught up in un-solvable little details, much easier to just put them in their place and move on.
This was the reason why I asked the question about the Diatribe to begin with.
If anyone has been harmed by those fakes I feel sorry for them however that is the way life teaches us what is right and what is wrong.
It is my experience that there are some Deals that shouldn't be pursued and IF I owned an Iphone or any other Expensive piece of electronics...
I would make Dam*ed sure that what I used on Any of MY equipment was tested proven and reliable because ultimately...
It's MY responsibility If it is defective or a phony.
Trying to get a return on an item of that nature is nearly impossible, So I have a simple rule.
I never buy any accessory of that nature that I would feel bad about throwing away as tossing the thing is usually much easier than returning it and certainly less bother than trying to get any other kind of satisfaction.

Bpb
--> WA7EMS <--
"The solution of every problem is another problem." -Johann Wolfgang von Goethe
I do answer technical questions PM'd to me with whatever is in my clipboard

Constantin

#24
Dec 09, 2012, 03:40 am Last Edit: Dec 09, 2012, 05:06 am by Constantin Reason: 1
Two ways to look at it, I guess.

That said, there are a handful of appliances I have torn down (among hundreds) where I wondered how the appliance had gotten its regulatory approvals.

For example, I recently repurposed a new, name-brand toaster oven with a reflow oven controller and was surprised to see that approved appliances may feature long, uninsulated metal assemblies connecting the heating elements, covered only by the exterior skin of the appliance and featuring a small air gap. One dent into the side of the oven and you'd have a direct short to ground.

Friends of ours had their DCS range weld itself shut thanks to a interior short.

When I took apart a failed (un-modified, just used) toaster a couple of years ago, several PCB holes no longer featured solder due to overheating.

Thanks to crummy design, a Kenmore vaccum cleaner in my home almost caught fire last year. Fully-approved unit but you can't help stupid when it comes to designing an power interface where large inductive currents pass through 2 comparatively small connectors that are repeatedly connected and disconnected (as one does with the wand/floor thingie on a vaccuum).

Most CO detectors sold in the US are built to a specification (UL-2034) that expressly allows long-term CO-poisoning. As a result, I gift friends with furnaces who are expecting with a CO experts unit. Most think its odd until I explain the issue.

ABYC allows the use of untinned wiring on ocean-going vessels, as long as you use some sort of connector on the end that may or may not keep the water from the wire.

In MA, a piece of plumbing hardware like a bathtub is not considered 'safe' to install, unless the manufacturer has paid a local license fee. Not sure if the license actually involves an outright review of the product or if it's just revenue collection. Either way, if a un-licensed piece of equipment is installed, the plumber doing the work is liable for any damages.

Bottom line: Approvals can be useful to help prevent the most obvious issues. However, they are not by themselves a guarantor of quality or adequacy. After all, many safety standards were written by industry and adopted by the 'regulatory' agencies that derive their income from said industries. Foxes guarding the henhouse and all that.

But, such standards are very useful when comes to defending lawsuits - the device 'met all applicable' regulations, right?

Docedison

There is unfortunately a flaw in human nature that says that anything that makes money is inherently ok, I see it constantly. This was the reason for my statement about tossing anything I don't like the looks of. I've not figured whether it is repairable through education or not. It manifest's itself as a basic lack of integrity... like selling toaster ovens that blow up if dropped when energized, Un grounded devices with exposed wiring or the equivalent next to metal panels that frequently are near metal sinks, un painted ones at that. I've never been able to find any justification beyond the increase in largess of the people responsibly for perpetuating those frauds and I consider that a poor justification indeed to sell something that might Can Kill people.

Bob
--> WA7EMS <--
"The solution of every problem is another problem." -Johann Wolfgang von Goethe
I do answer technical questions PM'd to me with whatever is in my clipboard

oric_dan

Quote
I actually use what I make and with one exception where I didn't have the proper sized fuse and did smoke a power transformer due to a shorted diode because I didn't utilize the proper transient protection... I've Never had a problem.


I'm not worried about you using what you design yourself, as you know what you're doing, and it's
your house. Of the rest of your post, I'd say you sound like you agree with me more than not agree
with me.

Final word: Caveat Emptor.

Quote
That said, there are a handful of appliances I have torn down (among hundreds) where I wondered how the appliance had gotten its regulatory approvals.


Your litany of disasters with approved stuff makes me feel even better about buying
unapproved stuff, especially if I can get it really cheap.

Docedison

I don't really have any answers, unfortunately... Just a compendium of little tricks to avoid getting knocked about quite so hard. as to the 'people' complaining about quality of Asian Goods... My thoughts are that people shop there because it's a place to buy knock off's, cheap ones at that from nameless little stores somehow with the thoughth that Ebay makes a difference. I own a  Bang and Oluffson  StereoCenter 7700 with remote that I would like to restore one day. Imagine a full stereo with a cassette deck and a remote with a turns counter, VFD display and two way communications between base and remote... From 1982, 30 years ago and an Akai receiver of similar vintage both are in a similar state of repair and I have more faith in the B&O than I do in the Akai ever working again. The old adage is still true, You Get What You Pay For. The same thing applies to the Asian Stuff... Why anyone would consider saving a dollar by buying a "Cheap" accessory for an expensive piece of electronics is beyond me, then to complain about a lack of regulatory integrity as is it were new is really more than I care to try to wrap my poor little head around.

Bob
--> WA7EMS <--
"The solution of every problem is another problem." -Johann Wolfgang von Goethe
I do answer technical questions PM'd to me with whatever is in my clipboard

Constantin


Your litany of disasters with approved stuff makes me feel even better about buying unapproved stuff, especially if I can get it really cheap.


Not sure that was the intent.... :P I thought I was pretty clear in illustrating the pitfalls of relying on approvals for safety. Approvals may be faked, approvals only imply safety, not guarantee it. Given a choice, a 'real' approval sticker (i.e. requiring a process where someone qualified reviewed a design, its assembly process, quality control, its components, etc.) is better than nothing.

Anytime you stick something into a mains circuit there is a risk you take... an approval may reduce that risk... then there is brand of the product, which may or may not mean something (i.e. re-branded Sony CDs vs. Sony alpha camera), then there is the reseller of the product (i.e. Digikey vs. no-name Shenzen), and lastly your ability to mitigate issues. But even all factors taken together do not guarantee performance... note the electrolytic capacitor disaster a couple of years ago that had all sorts of electronics blowing up, branded or not. They've even found faked LM7805s out there, which is just completely nuts.

As for the B&O gear vs. Akai repair from DocEdison, I'm not qualified to answer that question. My teardown work commenced in 1996 and has centered mostly around appliances and light commercial equipment. My dad once owned a beocenter 7007. I got the sex appeal re: the design but the audio performance, well, I wasn't too impressed (sorry). That's not to say that my gear has been flawless either - my pre-amp has issues with its channel selection, the amp has been repaired at least once or twice. Nothing is perfect.

Constantin

#29
Dec 09, 2012, 03:36 pm Last Edit: Dec 09, 2012, 03:38 pm by Constantin Reason: 1
Karma is back indeed!

I talk about appliance failures and the condenser fan on our fridge croaks. Rigged a external fan until I can get a replacement. Temperatures inside fridge are decreasing but I wonder to what extent I cooked the mineral oil and the compressor - it was way too hot to touch.

Just brilliant. Naturally, on a weekend when we're expecting 20 people over with small kids for a birthday party.

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