Banggood resistors

[Stuartambient]

I'm just starting out with electronics (mostly) and was looking at resistor kits.  While I'd like to order from Digikey and get a good brand I'm wondering if anyone has experience with these from Banggood
http://www.banggood.com/Wholesale-400pcs-Metal-Film-Resistor-Assortment-Kit-Set-20-Kinds-Value-Total-p-53233.html

I know they say metal film and am aware of the "fake" Chinese resistors that are actually carbon but for a beginner experimenting some small circuits maybe they are ok? I guess my concern is that they die during a test and the rest of the components burn. 

Thanks for any feedback!

[nanofrog]

They'll be fine. 

[Stuartambient]

They'll be fine. 

Ordered! Thank you.

[linux-works]

be aware of how things fail.

carbon fails as an open, usually.  is a failure of a part where an open-circuit would happen ok?

metal film fails as a short, usually.  same kind of question.

people often don't think about this or don't care, but since you are starting out, might as well inform you so that you'll know.

I have mixed feelings about 'cheap parts'.  in a way, its a good start and does not cost a lot, but there can be so much doubt in bad parts, even simple switches or resistors - and if your circuit does not work, is it because of YOU or THEM?

I hate having doubts like that.  with test gear, I need to know that I can trust it.  pretty much same with parts.

how bad can this or that cheap part be?  you'd be surprised.

just be careful.  so much can be gotton wrong in a fake or intentionally cheaply made part.  the 'savings' is not at all obvious if your circuit works only sometimes or shows some strange behavior.

[Stuartambient]

Wouldn't it be better with an open circuit failure, with no current going forward?

I'll test out the variety by a few of each kind and see how they do.  Anyway, yes these were cheap but the ones down the road were 2x the price and the reviews weren't that favorable. They'll come from CA otherwise it was $2.70 from China     

I just had a pack of 500 in my hand and now it seems to have disappeared.  They seemed okay and were from American Scientific Surplus...something.  The first pack I had were from Make and didn't seem all that reliable.  BG has been alright with me and usually their parts have been acceptable. 

Guess I will find out soon enough whether I got a 'deal' or not and go from there. 

[wraper]

be aware of how things fail.

carbon fails as an open, usually.  is a failure of a part where an open-circuit would happen ok?

metal film fails as a short, usually.  same kind of question.

Have you ever in your life seen metal film resistor failing short? Sometimes they can reduce resistance if transients are applied to them. But that is few tens of percent maximum and very rare. On significant overload they just fail open.

[linux-works]

Wouldn't it be better with an open circuit failure, with no current going forward?

think of this case: a feedback resistor on an op-amp.  when R goes higher, gain goes higher, all else kept the same.

all I'm saying is to think about more than just temp-co, value, power handlilng and tolerance.  how a part fails is also part of the decision process, even though - like I said - most people ignore it or have long forgotton this idea.

the reality of getting fake parts into production is not zero and so I do think its part of the design process to at least think about what can happen if this type or that type of part is used and if its fake or just made cheaply.  can you do something in your topology to try to fight this?  that sort of thinking is useful in making 'defensive designs' - ones that can withstand abuse in many angles, so to speak

[ovnr]

On open circuit failure: Say you have a voltage divider going into a sensitive opamp frontend, and the lower (signal to ground) resistor fails. Suddenly you have a hundred volts going into your opamp. Will it enjoy it? Unlikely. It might survive if it has decent ESD diodes, but not everything does.

It would be preferable if it failed short in this case. Of course, the flip side is true for the upper resistor in the divider; if that fails short, it will fry everything downstream.

[Stuartambient]

On open circuit failure: Say you have a voltage divider going into a sensitive opamp frontend, and the lower (signal to ground) resistor fails. Suddenly you have a hundred volts going into your opamp. Will it enjoy it? Unlikely. It might survive if it has decent ESD diodes, but not everything does.

It would be preferable if it failed short in this case. Of course, the flip side is true for the upper resistor in the divider; if that fails short, it will fry everything downstream.

Sounds wonderful 
So is there something with resistors (could be other components) where if they don't fail in the first week they'll probably last forever or there is always a risk?

[linux-works]

one of the things you get from -real- brands is that they do research, they stick with a material type and they spec it out and publish the specs (more or less, overall its far more true of branded than no-name parts).

the no-name parts could vary a lot, could have impurities, could fail later on down the line for ANY reason.  too much use, even too LITTLE use.

you have no idea.  none at all.  what's inside, how it was made, was it a 'last long enough to collect customers money' kind of part and business?  some parts are like time bombs; the e-lytic caps are the usual example of that.

if there is a way to cheap-out, the eastern manufacturers will find a way and do it.  I wont trust no-name parts in real builds and often, its a waste of time to use them in even informal builds that are just for me.  again, a parts failure or some strange behavior in a complex circuit could cause me days of tshooting and sending me down some wild goose chase.  I don't need to waste time like that.  life is too short to chase geese when you have better things to do

"I'll just buy parts that are so easy, they can't be that bad"

oh yeah?  time and time again, I am tempted to try some amazon special on some parts I would use a lot of.  and every single time, I have been disappointed in the metal or plastic or fitment.  its just not cost effective in the long run to buy shady stuff and then waste time on it.  you end up buying twice, plus the time spent is never recovered.

just some food for thought.  lowest -purchase- price is just ONE thing to look at.  its never the whole story.

[Audioguru]

Resistors in my cheap solar garden lights are hand painted with awful colors. Red, orange and brown look the same. Blue and green look the same. The resistors have iron wires that rust away in one month when the product is outdoors.
My American or European resistors are not expensive, are machine painted with good colors and do not rust.

[Brutte]

Tolerance: 1%, power: 1/4W, metal film, we ship from HK, welcome you.

Pick the highest and lowest value from a batch of one nominal value. If the voltage divider indicates the ratio higher than 2% then these are "chinese brown" 

[janoc]

Sounds wonderful 
So is there something with resistors (could be other components) where if they don't fail in the first week they'll probably last forever or there is always a risk?

Resistors, even Chinese cheapies, are not something that fails often, unless you abuse them with excessive current, voltage or mechanically. If the pack from Banggood is cheap, just go for it, it is probably only a few bucks that you would lose in the worst case. I wouldn't buy precision resistors from such place, but for general tinkering they are most likely more than good enough. I am often buying similar resistor/capacitor kits to stock up my component drawers and never  had significant issues. You can get rusty parts even from Farnell, so ...

For experimenting with some basic circuits you really don't need to care about whether the resistor is metal film or carbon, it is more important to actually have that resistor in the first place.

When buying components on AliExpress/eBay/Banggood, etc. always check the reviews/feedback of the seller, ideally on the same item. If there is a problem with it, someone will have likely pointed it out already. You could always get a DOA item, though. Shit happens, but most sellers even from China will try to help you out, because they care about their ratings (bad rating = no sales, the competition is really cutthroat and margins slim there). Just be reasonable and don't demand a free replacement for a $2 item no matter what. If the seller offers that, fine, otherwise the logistics around will cost the seller more than the item. In the few cases I had to deal with this, I have got a discount on next order or the replacement has arrived with the next order. Both fine with me. Returning money is rare, because it is expensive for them and a hassle unless you have paid with something like Alipay, especially for a small order.

I am also vary of items with 0 feedback - there you are on your own. Most likely the item will be OK, but it could also be a major lemon. Buy only if you will not mind throwing the item in the bin should it not be as you have imagined.

Now what I am rarely buying at these places are semiconductors - the chance of getting fake parts, especially for popular and easy to fake components (= relabel similar but much cheaper part, so it sorta works ...) is fairly high. Things like power MOSFETS and ICs I will rather order from an official distributor. On the other hand, if you only need a few jellybean transistors and LEDs for breadboarding, that's mostly no problem, even if you get relabeled/fake parts. They will rarely sell you a transistor or LED that don't work at all and for a breadboard it doesn't really matter if the LED dies 50% earlier than a real KingBright or Cree one.  Power LEDs can be iffy, though, often with dead chips.

The other thing I don't recommend buying from China are electrolytic capacitors, especially if it is for repairing a switching power supply. You will almost universally get junk.

Basically, if you are buying parts for just trying things out and learning, don't worry too much about it. If it is for something critical - like a school project, power supply that could fry something expensive if it fails, something for your job, demo for the investors of your startup - there saving a few pennies by not buying from a big name distributor could cost you a lot more if you get unlucky. As always - it is a trade-off.

[ZeTeX]

Resistors most of the time you can get metal film resistor from eBay no problems, but capacitors? totally different story.
Never ever build a project using one hung low capacitors, they will fail and they are not meeting their specs 50% of the time, go only from good brands - and most of the time they are not expensive at all.

I never had problem with eBay resistors, they are really just a resistor and for general purpose stuff I think they are great.
I know that one hung low caps have very bad reputation as they fail a lot, but what about resistors? do they also fail a lot compare to a good brand? did somebody test it?

[T3sl4co1l]

I can't even imagine why you'd shop for something like resistors at a cheap Chinese retail site like that.

Digikey, of all places, makes a good bit of their money on production quantities of resistors and capacitors.  They're competitive, and manufacturers know it.

Not that their small quantity pricing is very generous, but it won't be from any place that sells parts of higher quality than floor sweepings.

If you just need a random kit of values, just to get started, sure.  Just don't complain if they're impossible to solder, or out of tolerance, or burn out easily, or age terribly, etc.  This is the risk you are taking.  Be aware of that risk, and accept it.

You can replace values as you go, buying strips of a few hundred from mainstream suppliers, so that your collection improves in quality with your knowledge and experience.

Tim

[linux-works]

don't underestimate how badly things can be made.

I bought some color coded vertical pin headers, usual .1 spaced stuff.  "how bad can it be?" I thought.  there are 2 things, the plastic and the metal pins.

well, you can imagine that this was also a lesson for me.  the plastic melts if you look at it the wrong day.  or if you happen to be soldering on a day that ends in the letter 'y'   the metal, it would not easily take solder and since I had to leave the iron on longer to get any kind of connection, the plastic melted and deformed.  useless.  had to throw it all away.  nice bright pretty colors, though!  beautiful plumage, mate!  (lol)

look, the race-to-the-bottom is in full swing right now.  things that you think 'how bad can it be?' - are PRETTY DAMNED BAD.

brittle plastic, colors that fade or wash away (color codes), wires that have unknown metals in them, unsolderable in any clean way, materials that are brittle and break with strain or temp changes.  the list goes on and on.

the depths of 'cost savings' that vendors will go to has no limits.  no limits at all.   they'll happily make things they KNOW will blow up in your face.  they simply don't care.  this is the world we live in and its useful to know this rather than find it out the hard way.

[Stuartambient]

Thanks guys! At this point I'm still struggling with bending the leads and getting them to go into the breadboard straight 

If I blow half the pack just practicing that part, it was money well spent.  Banggood is alright but I know they are cheap no name possibly unreliable components.  It'd be nice to have a place to shop close by if I am going to need things in small quantities.  But with digikey they ship usps and for under a pound it was a few dollars. A pound of parts is quite a lot I imagine. 

Good to hear about other components like caps, semiconductors, etc.  BG has bags of those as well but I'll avoid.   Once I refine my list of needed parts I can try Digi-key or Mouser, or anyone that sells known stuff.  I was looking at Sparkfun which is about 15 minutes or so away.  From comments on their site products vary in quality but also noticed that while they have most common components, value ranges have some gaps. 

[nanofrog]

Thanks guys! At this point I'm still struggling with bending the leads and getting them to go into the breadboard straight 

If I blow half the pack just practicing that part, it was money well spent.  Banggood is alright but I know they are cheap no name possibly unreliable components.  It'd be nice to have a place to shop close by if I am going to need things in small quantities.  But with digikey they ship usps and for under a pound it was a few dollars. A pound of parts is quite a lot I imagine. 

Good to hear about other components like caps, semiconductors, etc.  BG has bags of those as well but I'll avoid.   Once I refine my list of needed parts I can try Digi-key or Mouser, or anyone that sells known stuff.  I was looking at Sparkfun which is about 15 minutes or so away.  From comments on their site products vary in quality but also noticed that while they have most common components, value ranges have some gaps.

If you can wait a bit on delivery, Tayda Electronics might be of interest, as the parts are inexpensive (located in Thailand). Definitely suitable for bread boarding (jellybean parts).

Regarding electrolytic capacitors, stick to name brands.

[Stuartambient]

If you can wait a bit on delivery, Tayda Electronics might be of interest, as the parts are inexpensive (located in Thailand). Definitely suitable for bread boarding (jellybean parts).

Regarding electrolytic capacitors, stick to name brands.

I was thinking about them actually.  Seen them mentioned in some other threads.  I'm not sure if I read much on the quality though.  One thing that interested me about them is they have a warehouse in Durango, which is within my state.  Nothing on their site though indicates where parts are located or a way choose.

I can't tell who makes their resistors.  I saw some elytic caps with Vishay on them, so I gather they are for real. 

[nanofrog]

If you can wait a bit on delivery, Tayda Electronics might be of interest, as the parts are inexpensive (located in Thailand). Definitely suitable for bread boarding (jellybean parts).

Regarding electrolytic capacitors, stick to name brands.

I was thinking about them actually.  Seen them mentioned in some other threads.  I'm not sure if I read much on the quality though.  One thing that interested me about them is they have a warehouse in Durango, which is within my state.  Nothing on their site though indicates where parts are located or a way choose.

I can't tell who makes their resistors.  I saw some elytic caps with Vishay on them, so I gather they are for real.

The resistors are usually from Royal Ohm.

For example, go to Coated, then Metal Oxide from the drop-down list, and you'll get the relevant data sheet.

[System Error Message]

Just thought i would offer some advice here about testing. Components perform differently under different conditions such as when under load or even under temperature.

If measuring the resistance can be done in parallel, measure it while it is active with load. Does the component get hot during testing? Does the resistance change? For learning i think cheap components are the way to go as you probably wont be using them in anything critical. If you plan on using them to repair stuff or as a business you should test the component to see how it performs normally and when at worst for it's purpose. Dont forget a voltage test to see if something like resistance would still be the same under different or even very high volts if the component will be used with lots of volts.

Also component lifespans can vary as well. Some things can be cheap because they are simple and will last long. Resistors are just a long piece of cable so theres nothing to them other than the material used to make them. Cheap resistors do fine as long as you dont pass too much energy through them.

[FlyingHacker]

I know there is always a lot of talk about failure modes, but most of these are purely anecdotal as far as I can tell when looking for actual data, rather than grey beard stories.

We need real hard data. Here is some, but even this does not go into detail about the sample sizes, etc.

http://www.electronicsbus.com/resistor-failure-modes-resistor-reliability-design-guide/

I think you should assume any resistor can fail open or it can fail short. It can also shift in value. There is not much of a hard and fast rule. Film resistors are not much more likely to fail short than carbon comp (just slightly, see the link).

Would love to see more in depth studies.

[macboy]

When you get them, check the temperature coefficient. This is a quick and easy test to see if they are in fact metal film or just cheap carbon ones painted blue. To do this, measure the resistance then (while still measuring) touch it with your hot soldering iron. They value should change very little if metal film; max 1 or 2 percent for a couple hundred degree C change. A carbon will change more.

[Stuartambient]

When you get them, check the temperature coefficient. This is a quick and easy test to see if they are in fact metal film or just cheap carbon ones painted blue. To do this, measure the resistance then (while still measuring) touch it with your hot soldering iron. They value should change very little if metal film; max 1 or 2 percent for a couple hundred degree C change. A carbon will change more.

Touch the resistor itself or leads?

[nanofrog]

Touch the resistor itself or leads?

The body of the resistor, not the leads.