Fake DS18B20

Other Hardware General Electronics
1

Hi all,

Just thought I should mention this.

I purchased 10 x DS18B20 temperature sensors from an Ebay supplier at the end of March 2018.
They came quite fast and in individual packages. Quite impressed as I had them in under 2 weeks.

Today, I came to use one of them, after connecting it to an Arduino Uno and running the oneWireSearch sketch, I could not get an address for it. I tried a few times, before I realised that this chip was getting very hot.

I immediately checked my wiring and confirmed that everything was ok, so tried again. This time I noticed that the 'ON' and 'L' LED's on the Arduino dimmed quite significantly.

I feared the worst that I had damaged the Arduino, but I inserted an old DS18B20 that I had some while and it worked fine.

I checked the physical difference between them and noticed number which has a '1541C4' marking on it, my older one having a '1523C4'.
A search on the internet brought up very little but did come up with someone on the forum having the exact same problem over a year ago and the sensor had the same '1541C4' marking on his.

Putting into a component checker revealed that it is a standard NPN transistor, worse still, all 10 were tested the same.
I have emailed the seller for a full refund before opening a dispute with Ebay and hope to get my money back.

So, has anyone else had a similar problem?

I have included here some images of the sensor, its packaging, the test and a real one.

Thanks

Martin

Fake DS18B20 1541C4 Packaging.jpg
Fake DS18B20 1541C4 Packaging.jpg1024×381 132 KB

Fake DS18B20 1541C4.jpg
Fake DS18B20 1541C4.jpg800×1024 70.1 KB

Fake Temperature Sensor.jpg
Fake Temperature Sensor.jpg1024×1030 390 KB

Real DS18B20 1523C4.jpg
Real DS18B20 1523C4.jpg683×1024 113 KB

2

You can't conclude from the component tester that it's actually an npn-transistor. Component testers can only give meaningful results for devices of types they are designed to identify; it doesn't surprise me that a digital IC would be mistaken for a transistor.

It does sound like there may have been either a bad batch (somehow? Surprising that they made it through QA), or a round of counterfeits (though with how cheap the real ones are, I question why anyone would bother faking them). The first part of that code is the date code, btw - 1541 = 41th week of 2015.

3

I bought few pieces of DS18B20 from local shop; these are marked as: 1619C4; they are working fine.

You have not posted your wiring diagram; so, we are not sure if you have made the right connection. Check the wiring as per following diagram and try again.

4

Cathprotech:
I purchased 10 x DS18B20 temperature sensors from an Ebay supplier at the end of March 2018.
They came quite fast and in individual packages. Quite impressed as I had them in under 2 weeks.

Yep ..... I purchased 1 lot of 10 pieces from ebay (as in... from an ebay seller) once. I tested them, and my lot were indeed transistors in disguise. I tested them myself. This was only after some time of 'interesting' situations, before I was aware of these fakes ....... where the very first one was used with an arduino board. I heard some kind of faint 'pop' at power up. Extremely faint....and wasn't sure whether it was a faint 'pop' sound - or my imagination. I assumed ''imagination'. Ignoring that, it turned out that I wasn't getting temperature readings. So tried another .... faint 'pop' again. So figured that I better check my circuits etc. Checked, double-checked, triple-checked. Tried another one .... 'pop' and very faint white smoke..... not much at all....but enough to see something wasn't going well. Tried a fourth...... same. Then decided to test with known 'good' DS18B20. No problem. That's when I figured something was quite wrong with this batch. Did tests .... npn transistors for sure. Ordered a second batch from the same ebay seller. Exactly the same. Reported it to the seller (who has very high rating). They took the item offline sometime after that.

If you go to 'google', then you'll find other people that have encountered the same situation. They've also gone out of their way to document it all.

All of my DS18B20 that I've ever bought were from ebay. As long as we find a seller that consistently sells the 'real' DS18B20, then just stick with that particular seller.

5

GolamMostafa:
You have not posted your wiring diagram; so, we are not sure if you have made the right connection. Check the wiring as per following diagram and try again.

As I mentioned, I tried a known good older one and it worked fine, hence wiring was good.

DrAzzy:
You can't conclude from the component tester that it's actually an npn-transistor.

Yes, but a good, original one shows something completely different so shows they are not what they are supposed to be and it shows as an NPN transistor. If it wasn't a transistor or any other identifiable component, it would not identify it as a transistor.

Anyone have a details of a trustworthy seller of these. Can you PM me?
Thanks

Hopefully the seller will refund.

6

Why post the good vendor links via PM? Do we need to keep a secret where to buy the good ones?

These forums do not have a rule against linking to vendor pages.

7

DrAzzy:
Why post the good vendor links via PM? Do we need to keep a secret where to buy the good ones?

These forums do not have a rule against linking to vendor pages.

Some seller called 'shieldsfans' or something along those lines has always sold decent items.

8

DrAzzy:
Why post the good vendor links via PM? Do we need to keep a secret where to buy the good ones?

These forums do not have a rule against linking to vendor pages.

Oh, in which case, then please post good reliable vendors.
I wrongly assumed there would be a rule against it.

Thanks

9

Hi,

I buy thousands of DS18B20's every year, many in the Waterproof version. I have a very reliable factory in Shenzhen, China ,which my partner visits personally, make the waterproof ones, and get the plain chip versions from them also. They obviously have to have genuine sensors to keep their reputation with many industrial users.

DISCLAIMER: Mentioning stuff from my own shop...!

See some here:

I guarantee these will be genuine and work...

10

I have purchased ds18b20 here and they have been fine.

11

Thank you for the suggestions.

I have ordered some from a UK seller as I needed them pretty quick now. Cost 3x more, but should be here Monday.

The seller I used in China offered me 50p refund at first, not sure if it was an error so told him the cost was £4.99 and this morning he refunded me in full.
So, maybe not a bad seller, just his supplier.

Thank you for the suggestions of where to buy from, I will keep them in mind next time I need them. Hopefully the ones I ordered on Friday from the UK seller will do for now.

Thanks
Martin

12

I have bought cheaply from Aliexpress from this Seller many times but never got any fakes. But the catch is that you have to use 4.7k between power and data line. Otherwise, it will not work!

13

Thanks, will check them out.

I think you are supposed to use a 4.7k resistor as a pull-up anyway.

14

Some DS18B20 module has a builtin 4.7K resistor.

15

I wasn't aware of that.
How do you know if it has a built in 4.7k resistor other than trying it without?

16

Hi,
There are MODULES that have pullup resistors and connectors, like this:

But the actual CHIP in a TO-92 case looks like this:

If you have the bare chip YOU need to provide the pullup resistor..

4.7K is nominal, two 10K resistors in parallel (5K) is fine.

On long wires, 2.7 K may be better.

NOT a critical value..

See THIS PAGE for lots of details and code...

17

Ah yes, the modules could have built-in resisors, but I was talking about the chips.

I have received 5 this morning from a UK supplier that I ordered on Friday, tested them straight away this time.

Got them from here.

Results below:

//
// Start oneWireSearch.ino
//
uint8_t pin2[][8] = {
{
0x28, 0x61, 0x64, 0x11, 0x82, 0x77, 0xE0, 0x4F },
0x28, 0x61, 0x64, 0x11, 0x8C, 0x6B, 0x65, 0xA9 },
0x28, 0x61, 0x64, 0x11, 0x8C, 0x64, 0x2E, 0xD7 },
0x28, 0x61, 0x64, 0x11, 0x95, 0x9C, 0xD8, 0x55 },
0x28, 0x61, 0x64, 0x11, 0x82, 0x74, 0x1E, 0x71 },
};
// nr devices found: 5
//
// End oneWireSearch.ino
//

18

Hi,
I read a while ago that some industrial equipment uses DS18B20's to set an internal serial number.

The manufacturer also makes serial number chips. BUT the DS18B20 is cheaper, and you can just ignore the temperature measurement capability.

19

That's an interesting use of them.

20

We have purchased 100s of DS18B20 from China, both plain and water-proofed with 1-2M leads. Recently I discovered that many of the water-proofed sensors, while they report a reasonable temperature, I cannot write to the user data (high/low alarm). All the working sensors report a high/low set-point of 75/70 from factory but these questionable ones show 255/255 before and after any attempt to change the set-points.

Has anyone else come across this?