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Topic: Fake DS18B20 (Read 5810 times) previous topic - next topic

Your quoting a message from 2 years ago, doubt they are still watching, although I am.

That is also for I2C, the DS18B20 is not I2C however it does still require a pull-up resistor

SteveMann

I rarely look at the post date since I just look at new posts.
I am usually so far out of the box that most people don't know what I am talking about.

Please do not ask for help by PM. I will not respond.
If you need help, post a question on the appropriate forum.
Click on Add Karma if I helped you.

MarkT

Try to check it, someone else may have necroposted - having said that I get caught out occasionally.
[ I DO NOT respond to personal messages, I WILL delete them unread, use the forum please ]

somewhereinusa



I had a quick Google for DS18B20 data sheets.
One lists the temperature range as -67° F to +257°F (DalSemi)
Another lists the range as: -67°F to +212°F (Maxim)
There are probably more manufacturers.

Not arguing, just trying to understand what's going on. I just downloaded 8 data sheets, including 2 that were from Maxim. They all list  -55°C to +125°C (-67°F to +257°F) for temp ranges.

Quote
I seem to recall that -196°F (-127°C) is the 'out of range' code and it is quite possible that the older ones you have don't issue an 'out of range' code and maybe just fail to give anything
Not sure about out of range. My experience has been -196°F shows with a bad/open connection. I have no way of getting anything anywhere near -67°F  and the current problem.  Some, the older lot of 10, simply not showing any rise above 262° until the temp falls below that. All but one did it at exactly 262.5 that one was 261.8. The last two lots of 10 ranged from 186-239 at which time they show -196. Since they are so inconsistent, is it always going to be at that temp?  This is a failure to me.

Quote
Obviously, I don't know what you are using them for, if the +200°F is just used to test them or if you require them to read that high.
If your using them with a micro-controller which I would assume you are as you are on this forum, then you could just add to your code to ignore the -196.6°F or print 'Out of Range' etc.
For general purpose use though, I don't think you have a problem. If they work as a temperature sensor then great.

Hopefully nothing will ever reach that point, although it is slightly possible. The problem is that about 36°F heaters are turned on and -196 is below that. I've tried putting that into code without success. I would prefer to just ignore any -196.6 that shows up.

#34
Apr 09, 2020, 05:22 pm Last Edit: Apr 09, 2020, 05:33 pm by Cathprotech
It does sound like you have fakes in the sense that they are poor copies of the genuine article with poor quality control hence the inconsistency in range, hopefully though, your use will be within range and if you didn't pay too much for them, then you got a good deal.

As mentioned before, the fake ones I had were not even copies, they were bog standard NPN transistor stamped with DS18B20.
When I tried them, I had errors on my Arduino Uno and the DS18B20 got extremely hot. I thought I had wired it up wrong, so I double checked and tried another (I bought 10). Same result. Swapped out for a previously purchased on and worked perfect.
Use a component tester which identified it as a general purpose NPN transistor, genuine (copies) just indicate damaged or unreadable component (as they should).
The 10 I purchased came in individual packets and very clearly labelled.
Luckily there was no damage done to the Arduino and I did get my money back from the seller.
See images attached (hopefully)



somewhereinusa

Just for the heck of it I tested 2 good and 2 bad ones. The bad ones, they do read temps, show as transistors. The good ones test as 2 diodes.








somewhereinusa

Have any idea about where to buy some that do work?

It gets stranger and stranger with these.

I think you just take pot luck.
Most Ebay sellers all get there electronics sent from the same warehouse, so doesn't matter who you order from you just take you chance.
I haven't bought any for a while now, so cannot advise of anywhre.

The last ones I bought were in the UK so I could send them back if they didn't work. Luckily they did.
Maybe from someone in the US then, easier to return if fake.

Other than that maybe find a good crystal ball seller and then tell me as I need one for the missus!


terryking228

#38
Apr 10, 2020, 02:05 am Last Edit: Apr 10, 2020, 03:58 pm by terryking228
Quote
Have any idea about where to buy some that do work?
****UPDATE****
*****UPDATE*****
***SOME*** of the sensors I have in stock in USA fail the test and are shown as a clone. 

I do know that our supplier makes waterproof sensors from two suppliers, both MAXIM and also some well-known chinese clone maker.  The price is somewhat higher for the guaranteed MAXIM, and we have that specified for a couple of our large customers.  It appears that when we ordered some sensor for our own stock we got the clones. 

If you want guaranteed MAXIM we will have to order that specifically for you.  I will inform a couple of recent customers about this and refund if desired.. 

If someone wants samples of the two variants let me know...

Sigh....

----( Previous post)-----

We have an excellent factory in Shenzhen that makes the waterproof DS18B20 units we sell. Other than a few cable lengths / quantity, they build them to order.  I have a few of the 4M and 10M length here in Vermont USA..

We have sold over 10,000 over 4 years to a large USA automation system company, with good results and almost zero defects.  See: (Sorry LONG URL...)

=DS18B20&s[title]=Y&s[short_desc]=Y&s[full_desc]=Y&s[sku]=Y&s[match]=all&s[cid]=0]http://www.yourduino.com/sunshop/index.php?l=search_list&s[search]=DS18B20&s[title]=Y&s[short_desc]=Y&s[full_desc]=Y&s[sku]=Y&s[match]=all&s[cid]=0

Shipping: DHL.. We recently shipped 1000 units over 2 weeks to miss the 25% tariff..  Email me for quote.

DISCLAIMER: Mentioned stuff from my own shop... but 'someone asked...'
Regards, Terry King terry@yourduino.com  - Check great prices, devices and Arduino-related boards at http://YourDuino.com
HOW-TO: http://ArduinoInfo.Info

Paul__B

I've always found this seller Alice to be reliable.  I've been purchasing from them for a number of years and have always received good parts.   I personally like the fact that they have been around for a long time.
Having some suspicions that "Alice" is either the same as "worldchips" or in the adjacent bay.  As with many eBay "shops".

Most Ebay sellers all get there electronics sent from the same warehouse, so doesn't matter who you order from you just take you chance.
That is clearly the case.

I've found as their reputation grew their price became a little higher, but these folks cannot be making much profit so I stick with them.
And "Alice"s prices have recently nearly if not doubled.  In addition, an absurd postage charge has just appeared.  I have been ordering stuff recently, but wondering whether I will actually get it!

MarkT

Have any idea about where to buy some that do work?

A reputable electronics stockist of course.  Digikey, Element 14/Farnell, RS, Mouser, many others round the world.
[ I DO NOT respond to personal messages, I WILL delete them unread, use the forum please ]

terryking228

Please see the update to my previous post..
Regards, Terry King terry@yourduino.com  - Check great prices, devices and Arduino-related boards at http://YourDuino.com
HOW-TO: http://ArduinoInfo.Info

somewhereinusa

Please see the update to my previous post..
Terry, I placed an order for 10 last night. Please advise.

terryking228

#43
Apr 10, 2020, 05:10 pm Last Edit: Apr 10, 2020, 07:37 pm by terryking228
Quote
I placed an order for 10 last night. Please advise.
OK Did some testing... Result: All the waterproof sensors I have here in USA are with chips from the Chinese Supplier I know we have used before.  I should have known that: The sensors we specifically have made for 2 large customers are more expensive with guaranteed MAXIM chips.. 

I have a few TO-92 MAXIM chips (Good laser label, "p" on back) that read properly, like this:

-------( Reads "Genuine Maxim" )-----------------------------------------
28-5F-85-C8-0A-00-00-42: ROM ok.
  Scratchpad Register: 73/01/4B/46/7F/FF/0D/10/41
  Info only: Scratchpad bytes 2,3,4 (4B/46/7F):  Maxim default values.
  Scratchpad byte 5 (0xFF):  ok.
  Scratchpad byte 6 (0x0D):  ok.
  Scratchpad byte 7 (0x10):  ok.
  0x4E modifies alarm registers:  ok.
  0x4E accepts 10 bit resolution:  ok.
  0x4E preserves reserved bytes:  ok.
  0x4E accepts 12 bit resolution:  ok.
  0x4E preserves reserved bytes:  ok.
  Checking byte 6 upon temperature change: not necessary. Skipped.
  --> Sensor responded like a genuine Maxim.

And the waterproof sensors from the factory we have a personal relationship with that have the chinese 'good clone' chips:

---- ( "HIGH QUALITY CLONE CHINESE CHIP" )----Waterproof Package
28-FF-1F-73-A4-16-05-6A: ROM does not follow expected pattern 28-xx-xx-xx-xx-00-00-crc. Error.
  Scratchpad Register: 50/05/4B/46/7F/FF/7F/10/FF
  Info only: Scratchpad bytes 2,3,4 (4B/46/7F):  Maxim default values.
  Scratchpad byte 5 (0xFF):  ok.
  Scratchpad byte 6 (0x7F):  unexpected value. Error.
  Scratchpad byte 7 (0x10):  ok.
  0x4E modifies alarm registers:  ok.
  0x4E accepts 10 bit resolution:  ok.
  0x4E preserves reserved bytes:  no, got: FF/3F/10. Error.
  0x4E accepts 12 bit resolution:  ok.
  0x4E preserves reserved bytes:  no, got: FF/7F/10. Error.
  Checking byte 6 upon temperature change: not necessary. Skipped.
  --> Sensor appears to be counterfeit based on 4 deviations.
------------------------------------------------------------------------------------------

There are apparently other clones out there, with different failing patterns... 

That's all I know right now... refunding one order where this was not clear...

Regards, Terry
Regards, Terry King terry@yourduino.com  - Check great prices, devices and Arduino-related boards at http://YourDuino.com
HOW-TO: http://ArduinoInfo.Info

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