Chinese Parts

[phil from seattle]

How much time do you spend:

1. Researching the circuit?
2. Designing the circuit?
3. Making the schematic?
4. Ordering the parts?
5. Laying out the parts?
6. Assembling the unit?
7. Testing the unit?
8. Debugging the circuit?
9. Fixing the circuit?

Now apply a wage rate for each of those times. Do the times differ due to the supplier of the parts? If there is x% of risk associated with a part being operational, how many total hours does that add to the work? What is the total cost difference?

This is a good point but you should always test any Chinese parts before using. So, there is additional time overhead. The real issue for me is if the parts are bad, it delays my project for a least a week if I have to mail-order replacement parts. So, generally, I get commodity parts from China and test them beforehand. I would not rely on a critical part bought that way. Well, with the exception of parts you can't get from distis (WS2812B and CH340 spring to mind).

[wraper]

standard analog are fine

Dunno, many people here received even Fake LM358, not to say there is close zero chance buying genuine "audiophile" opamps.
I personally usually buy only specific stuff where it would need to be counterfeited on silicon die level. Not just some other IC rebadged.

[ekg98]

I bought a set of 78xx regulators.  I am waiting for them to come in.  I was wondering if its good to load test them.  I thought about making a test setup but that does take time and expense.  I need to build a power supply.  Thats one thing I don't have yet is a decent adjustable voltage amperage supply. 

I most likely wouldn't use the 78xx for more than 500ma anyway.  Driving a few seven segments and timing sections etc.  Blinky lights.  CMOS. 

What books do you guys recommend on CMOS chips. 

[eblc1388]

What books do you guys recommend on CMOS chips.

I learn a lot from the book "CMOS Cookbook" by Don Lancaster.

He also authored Cookbooks on TTL and Active Filters. A great author in my view. I'm surprised that some members had remarked that there is nothing useful in the book.

[Specmaster]

When it comes to Chinese items, I check and check usually, I have have failed a few times however, the persons feedback if its good and the price is not the real bargain basement that some sellers offer, then I'm pretty happy to purchase.

However, beware of buying anything mains powered  as their UK plugs come unfused with no provision for a fuse even and also the earth pin is sleeved so that means that once the plug is fully inserted into a 13A socket you loose all grounding so the equipment could be floating then, so always as replace the plug at least and better still buy a decent lead from the UK for the item.. Also you need to open up and check for dodgy terminations, poor earthing and poor solder joints as sometimes the items could have been made by homeworkers who are not always subject to the same tests and inspections as those item made in a proper factory would be.

[ez24]

What books do you guys recommend.  I am trying to get my hands on a copy of the CMOS cookbook.  I hear this is a good book for CMOS chips.

Check Reply #3
https://www.eevblog.com/forum/other-blog-specific/a/msg1341170/#msg1341170

[SkyMaster]

I figured the case but I thought I would ask.  However I doubt most of the components on mouser or digikey are priced correctly.  Seriously they are making 1000% profit on some of these chips.  Lots of 25 of particular chips would be great but at reasonable prices.  Not $10 per ic type just for 25 chips that's ridiculous.  BGMicro is better and cheaper shipping but they don't have a super great selection of 4000 series.

BG Micro is a surplus type of store. I remember buying from them almost 25 years ago.

Mouser and Digikey have (almost) everything in stock, they ship the same day and depending on your location you can receive your order the next day.

It is entirely possible that you are shopping for through hole components that are now more expensive than their surface mount equivalent, simply because the production volume is less.

Now for the Chinese parts... If electronics for you is a hobby, and you are building circuits to have fun; where is the fun if your circuit is not working (or not working correctly) because you are using counterfeit/fake low cost parts? Not only that, but you may have to wait for weeks to receive your parts.

 

[ekg98]

This is partially true however some of the 4000 series can be twice the cost if your buying 10 vs 100.  Ontop of that mouser ships air most of the time.  The boxes are huge and they charge ridiculous amount for shipping.  Most of the time the shipping is more expensive than the parts I am buying.  I might need $3 in capacitors and maybe 10 resistors and I end up paying 8 bucks for shipping on 4 dollars in parts.  I could save up and order everything at once but then I would have a long wait inbetween working on projects.  I am en massing a quantity of parts over time yes so the situation will improve.  I am keeping my Chinese parts separate from my good ones from mouser.

Don't get me wrong.  I do love mouser and will continue to order from them.  Love the filtering on the search functions etc.  However for small orders and for my sake I don't know what I am looking for sometimes for a project.  Its incredibly hard to find some items in mouser without searching through a long list of parts.  Options are great but for somethings I just don't need that many.  Just looking for say a battery snap or rubber standoffs or rubber feet, etc.

I figured the case but I thought I would ask.  However I doubt most of the components on mouser or digikey are priced correctly.  Seriously they are making 1000% profit on some of these chips.  Lots of 25 of particular chips would be great but at reasonable prices.  Not $10 per ic type just for 25 chips that's ridiculous.  BGMicro is better and cheaper shipping but they don't have a super great selection of 4000 series.

BG Micro is a surplus type of store. I remember buying from them almost 25 years ago.

Mouser and Digikey have (almost) everything in stock, they ship the same day and depending on your location you can receive your order the next day.

It is entirely possible that you are shopping for through hole components that are now more expensive than their surface mount equivalent, simply because the production volume is less.

Now for the Chinese parts... If electronics for you is a hobby, and you are building circuits to have fun; where is the fun if your circuit is not working (or not working correctly) because you are using counterfeit/fake low cost parts? Not only that, but you may have to wait for weeks to receive your parts.

 

[bd139]

Also worth having a look at Tayda Electronics. It’s a step above the unknown and is usually pretty good quality. For example I tend to use the to buy wire from as I don’t need spools of it. 22 awg stuff is like rope compared to the generic Chinese stuff.

Stay away from the unbranded resistors though (they sell royal ohm which are fine though)

[HwAoRrDk]

Also worth having a look at Tayda Electronics. It’s a step above the unknown and is usually pretty good quality. For example I tend to use the to buy wire from as I don’t need spools of it. 22 awg stuff is like rope compared to the generic Chinese stuff.

You should check out CPC for cheap wire. Cheaper than Tayda! I discovered that they have a selection of 'Concordia' brand 24, 22 and 18 AWG wire for dirt cheap. Like, £0.25-0.50 per 10 metres. The only thing is that they have mis-attributed most of it (e.g. 24 AWG attributed as having "0.032mm²" cross-sectional area! ), so it doesn't show up when searching by wire size parameter. It comes up if you filter by brand name and then look at no. of strands / strand size to determine gauge.

[CJay]

You take a risk buying unmounted components from China, many are just outright fakes or poor quality (resistors and capacitors though there's little point in a 1% resistor for many hobbyist experiments, the Chinese 5% ones are perfectly adequate, Chinese multi pack capacitors are almost always rubbish for anything other than the least demanding application)

Semiconductors, while I have had good luck with the bubble gum transistors from China (2N3904/6, PN2222, BC547/557 etc.), I've found I can buy the transistors, regulators and cheap op-amps from local suppliers for very good prices and have them the next working day so it's just not worth the wait to order from China.

Larger chips, I tend not to buy unmounted chips, I buy assembled modules and have, as yet, never had a module that didn't work and they are almost always far cheaper than the cost of the individual components, even when they're not, it's an assembled module that's saved me a ton of time and it means I can spend the time on what I'm trying to achieve instead of debugging the chip implementation.

[bd139]

Also worth having a look at Tayda Electronics. It’s a step above the unknown and is usually pretty good quality. For example I tend to use the to buy wire from as I don’t need spools of it. 22 awg stuff is like rope compared to the generic Chinese stuff.

You should check out CPC for cheap wire. Cheaper than Tayda! I discovered that they have a selection of 'Concordia' brand 24, 22 and 18 AWG wire for dirt cheap. Like, £0.25-0.50 per 10 metres. The only thing is that they have mis-attributed most of it (e.g. 24 AWG attributed as having "0.032mm²" cross-sectional area! ), so it doesn't show up when searching by wire size parameter. It comes up if you filter by brand name and then look at no. of strands / strand size to determine gauge.

I order a lot of stuff from CPC. They're not that great on pricing. I'll give you some comparison:

2n3904 x100 ... CPC (On Semi) £4.80 ... Tayda (Fairchild) £1.47
10k RO 1% 0.25W x50 ... CPC £0.80 ... Tayda £0.44
74LS47 x1 ... CPC £1.19 ... Tayda £0.73

All adds up. Also Tayda stock better lines. Look at the pricing on their JST connectors compared to locally for example. I must have bought 100 shells, pins and headers for less than $2.   The wire from Tayda is also like rope compared to the exact stuff you mention from CPC. I was using that before a bought a few sample stretches to see. Also CPC never seem to have any stock of certain colours hence why I ended up with 10m of pink wire a while back. I have nothing against pink, but when I have a standard colour scheme for wiring, substituting red for pink because the lead time on CPC was 2 months is a bit much.

You take a risk buying unmounted components from China, many are just outright fakes or poor quality (resistors and capacitors though there's little point in a 1% resistor for many hobbyist experiments, the Chinese 5% ones are perfectly adequate, Chinese multi pack capacitors are almost always rubbish for anything other than the least demanding application)

Semiconductors, while I have had good luck with the bubble gum transistors from China (2N3904/6, PN2222, BC547/557 etc.), I've found I can buy the transistors, regulators and cheap op-amps from local suppliers for very good prices and have them the next working day so it's just not worth the wait to order from China.

Larger chips, I tend not to buy unmounted chips, I buy assembled modules and have, as yet, never had a module that didn't work and they are almost always far cheaper than the cost of the individual components, even when they're not, it's an assembled module that's saved me a ton of time and it means I can spend the time on what I'm trying to achieve instead of debugging the chip implementation.

China is ok for stock jellybean items. I keep a lot of parts on hands. Modules I rather like. Some of them are quite good. I have bought a ton of small switching converters recently and they all just work and I can't blow them up however hard I try.

As noted though, some capacitors aren't that great. The small electrolytics are fine, the tants are usually fine, but the big electrolytics and C0G ceramics are shit. I grab Suntan/Vishay ones for that from Rapid/Farnell. X7R ones doesn't matter; any old crap will do for decoupling. Some of the polybox/film ones are microphonic. I haven't had that from the Tayda ones (which are Arcotronics/WIMA)

[wraper]

I buy assembled modules and have, as yet, never had a module that didn't work and they are almost always far cheaper than the cost of the individual components, even when they're not, it's an assembled module that's saved me a ton of time and it means I can spend the time on what I'm trying to achieve instead of debugging the chip implementation.

DC/DC converter modules usually contain fake chips working at much lower frequencies and are completely not up to spec. Wireless modules usually contain counterfeit chips as well and often cause weird-ass issues that genuine ICs don't have.

[paulca]

I buy assembled modules and have, as yet, never had a module that didn't work and they are almost always far cheaper than the cost of the individual components, even when they're not, it's an assembled module that's saved me a ton of time and it means I can spend the time on what I'm trying to achieve instead of debugging the chip implementation.

DC/DC converter modules usually contain fake chips working at much lower frequencies and are completely not up to spec. Wireless modules usually contain counterfeit chips as well and often cause weird-ass issues that genuine ICs don't have.

Any demonstrable examples? 

I know there are Chinese fakes but I think people go too far on that party line.  Remember 99.9% of the "branded" components are made in China.

I have seen many YouTube videos where particulars of modules, include buck/boost converters have been tested against the chip datasheet and been withing a few percent of it... sometimes better.

Not saying these fakes don't exist, but you simply cannot build these buck/boost converters cheaper than they are being sold, even if you buy cheap Chinese components.

Also, check the price of the 100uH inductors on the likes of RS.  £7 each.  China, $1.  For a bit of wire wrapped around a ferite ring.

Someone listed the steps to building a circuit above.  It's relevant in more than one way.  If you take that list and add up the time for each step and plug in the average wage of an Engineer in the west you get a massively high figure compared to plugging in the wage of a Chinese worker.  Then you have to remove all the middle men, distributors, importers, retailers etc. etc. which in west all add HUGE amounts to the cost of a product.

When you do this and then factor in the trade deficits and balancing done to keep the Yen cheap against the dollar you will find these components are cheap from China because "they are cheap from China", not because the parts are actually "cheap" parts.   Take any example component and follow through all the western markup added to it when you buy from farnel.  Then do the same trace for a Chinese online retailer.  We are talking several orders of magnitude in mark up difference.

[Specmaster]

I buy assembled modules and have, as yet, never had a module that didn't work and they are almost always far cheaper than the cost of the individual components, even when they're not, it's an assembled module that's saved me a ton of time and it means I can spend the time on what I'm trying to achieve instead of debugging the chip implementation.

DC/DC converter modules usually contain fake chips working at much lower frequencies and are completely not up to spec. Wireless modules usually contain counterfeit chips as well and often cause weird-ass issues that genuine ICs don't have.

Any demonstrable examples? 

I know there are Chinese fakes but I think people go too far on that party line.  Remember 99.9% of the "branded" components are made in China.

I have seen many YouTube videos where particulars of modules, include buck/boost converters have been tested against the chip datasheet and been withing a few percent of it... sometimes better.

Not saying these fakes don't exist, but you simply cannot build these buck/boost converters cheaper than they are being sold, even if you buy cheap Chinese components.

Also, check the price of the 100uH inductors on the likes of RS.  £7 each.  China, $1.  For a bit of wire wrapped around a ferite ring.

Someone listed the steps to building a circuit above.  It's relevant in more than one way.  If you take that list and add up the time for each step and plug in the average wage of an Engineer in the west you get a massively high figure compared to plugging in the wage of a Chinese worker.  Then you have to remove all the middle men, distributors, importers, retailers etc. etc. which in west all add HUGE amounts to the cost of a product.

When you do this and then factor in the trade deficits and balancing done to keep the Yen cheap against the dollar you will find these components are cheap from China because "they are cheap from China", not because the parts are actually "cheap" parts.   Take any example component and follow through all the western markup added to it when you buy from farnel.  Then do the same trace for a Chinese online retailer.  We are talking several orders of magnitude in mark up difference.

I agree, I think China get to bad a press most of the time. I think that there are 2 major drawbacks to Chinese parts, the first is the length of time they take to arrive which can be weeks and the second is the language barrier when it comes resolving problems, sometimes it is very hard to get them to acknowledge the problem, not that they don't want to help because generally I find them very helpful indeed, but because they sometimes don't understand what we are saying. They need to employ some people who can speak English fluently to fully engage with the English speaking people and resolve problems.

That being said I think I can only recall 2 occasions where I have any problems in communication with them.   

[wraper]

I buy assembled modules and have, as yet, never had a module that didn't work and they are almost always far cheaper than the cost of the individual components, even when they're not, it's an assembled module that's saved me a ton of time and it means I can spend the time on what I'm trying to achieve instead of debugging the chip implementation.

DC/DC converter modules usually contain fake chips working at much lower frequencies and are completely not up to spec. Wireless modules usually contain counterfeit chips as well and often cause weird-ass issues that genuine ICs don't have.

Any demonstrable examples? 

https://zeptobars.com/en/read/Nordic-NRF24L01P-SI24R1-real-fake-copy
https://www.eevblog.com/forum/chat/lm3596-switching-regulator-modules/msg1189293/#msg1189293

Yes! I found it strange that the data sheet said the switching frequency is 150KHz but I was getting 50K(see attached).

https://www.eevblog.com/forum/chat/lm3596-switching-regulator-modules/msg1189387/#msg1189387

Each and every one of the LM2596 modules I've bought from vendors on the Amazon marketplace were using fake LM2596 chips, running at 51-52 kHz. See scopeshots (BTW, I believe the little bump before the spike to be an artifact due to too many averages - it did not show up in other acquisition modes).

[wraper]

Also, check the price of the 100uH inductors on the likes of RS.  £7 each.  China, $1.  For a bit of wire wrapped around a ferite ring.

Without specifics this comparison is useless, you might compare apples vs oranges. Also there are far cheaper places than RS.

Remember 99.9% of the "branded" components are made in China.

First of all, this is not true at all. If you said in order of like 50%, then I would probably agree. Secondly, don't mix the things together, China is very different, and you should separate what is sold on legit marker and what in Shenzhen sewers.
EDIT, I just took a few reels of components lying nearby:
Country of Origin: Singapore, Mexico, USA, Ireland, Malaysia, Japan, Thailand, China. Actually China seem to be in minority there, and those are pretty cheap components.

[Bud]

Also, check the price of the 100uH inductors on the likes of RS.  £7 each.  China, $1.  For a bit of wire wrapped around a ferite ring.

When writing my investigative post "Project Yaigol" about the piece of shit rigol DS2000 scope i discovered the inductors they used were single use ones, i.e. you cant generally reuse them because the wire is 'soldered' to the terminals, whereas in a normal inductors the wire is 'welded' to the terminals. When unsoldering such SMT inductors from the board the wires may come off of the terminals because of the surface tension of the solder as you pull the inductor away, so you end up with a open circuit. If you do not check the little bastard and solder it back or use it in an other circuit you end up pulling you hair trying to find why the circuit is not working. Also the inductor value may change because of movement of the wire if you try to solder the wire back to the terminal, which in itself is a fun exersise on a 0603 inductor. I found the same to be with chinese RF SMT transformers, the wire is Soldered, not Welded to the package terminals. Single use like condoms, that is.

[bd139]

I don't know any SMD parts that aren't single use. I certainly wouldn't reuse them.

[Specmaster]

Most of them are not marked to show the value anyway so once removed, assuming they remain intact, if they get mixed up with other parts you would have to test them each time in order to identify which part and value they were anyway, apart from that they are so inexpensive its worth your time to recycle them.

[soubitos]

Quote from: Specmaster on Today at 06:34:11 PM

Most of them are not marked to show the value anyway so once removed, assuming they remain intact, if they get mixed up with other parts you would have to test them each time in order to identify which part and value they were anyway, apart from that they are so inexpensive its worth your time to recycle them.

It does not hurt to keep a few computer motherboards and other pcb's in a box somewhere, dead or obsolete or else. I have been saved more than once by getting a capacitor or resistor or diode out of them .... be careful and you CAN reuse smd parts.... of course it all comes down to your tools too, i dont see how you can do it properly without hot air "rework" tool, proper flux, solder, magnification etc.. 0805 and up possibly ok but anything smaller you need more than a soldering iron some 60/40 and a solder sucker .... LOL.....

[Specmaster]

It does not hurt to keep a few computer motherboards and other pcb's in a box somewhere, dead or obsolete or else. I have been saved more than once by getting a capacitor or resistor or diode out of them .... be careful and you CAN reuse smd parts.... of course it all comes down to your tools too, i dont see how you can do it properly without hot air "rework" tool, proper flux, solder, magnification etc.. 0805 and up possibly ok but anything smaller you need more than a soldering iron some 60/40 and a solder sucker .... LOL.....

I have all of those items but I'd have to be really desperate to attempt to recycle them, just the heat stress alone is enough to seriously damage them to the point that their values shift at best and at worst destroy them. 

[bd139]

I spent years working with salvaged parts and I can't be arsed these days. It's too much like hard work.

BTW china win: 200x 5mm UV LEDs £1.67. All work. RS = £69.60.

[soubitos]

I obviously dont imply putting new pcb's together with salvaged parts, that would be... both time consuming, impractical etc but also plain crazy... but, when i need to repair say a motherboard with a fried mosfet another dead mobo has the same part and lies there, then by all means i will go into the trouble and make the effort to salvage it and do the repair (the alternative being ordering parts, waiting, paying too much on shipping for an otherwise cheap part and so on).... if it works and passes testing, stress test if possible etc then it's all good to go... customer saves a LOT of money, gets faster his board or computer or whatever and provided you tell them what you did and that parts used to repair are used etc, its all fine....

Back to CHINESE parts though, i have ordered quite a lot to make repairs... the bigger problem with customers was waiting for the part, their alternative being to pay 5-10-100x as much for parts to repair their product almost always makes that easier...  Most of the times i order multiples of the number required so i create a small stock of parts known to possibly fail (which costs ME nothing).... of course, i have tested vendors etc but for crucial, potentially dangerous parts etc i would either test each and everyone before using or go the high way and pay!

[wraper]

I spent years working with salvaged parts and I can't be arsed these days. It's too much like hard work.

BTW china win: 200x 5mm UV LEDs £1.67. All work. RS = £69.60.

At this price the only thing you can expect is bunch of defective (like current leakage) and unreliable junk.