Have you tested them to see whether they are not just remarked transistors?

 

Have you tested them to see whether they are not just remarked transistors?

That was my suspicion also. If they were purchased from the “usual suspects”, you already know who they are, those LM35 may really be only blacktopped and remarked transistors.

 

This is what my LM35CA is showing

thank you - this is what I needed to see !
Can you also mount your LM35 into a transistor tester like mine (in the picture GM328A or similar)and take a read and a picture of it? Just to be sure. A direct comparison is worth 1000 words.

Have you tested them to see whether they are not just remarked transistors?

Thank you; It crossed my mind to do this test and I just forget to make it. Im getting old.
This is what is showing me: (I am screwed)
;;
Left ones are all tested and also the plastic a bit burned from my hot iron tests. If you zoom into the image you can see the burn marks.
Right ones are untouched.
Their laser marking:
The original order price for 10pcs. Look how he is lying "100% New" - unbelievable.

I also denounce that seller, I hope aliexpress website will take some action about it. And if they dont, at least I'm mentioning here.

also here is a transcript of the letter I wrote to them:

 

This is what my LM35CA is showing

<<- Can you test your LM35 on your GM328A transistor tester ?
I'm curious what it will show !
It will also show a transistor? or it will complain that is an unknown component ?
Because after all it is a chip inside and not just a simple transistor like it showed in my reading.
Thank you - you are a life saver so far!
How shitty it is when you first try a component and you dont know how it should behave!
It will be very cool to be a website specific for this problem, with tested components and showing their behaviour in pictures and short movies. Mmmm. To know what to expect from them !

 

I also denounce that seller, I hope aliexpress website will take some action about it.

It's unlikely that AliExpress will do anything after their dispute window closed.

if they dont, at least I'm mentioning here.

You can report the info in my thread in the Marketplace forum. I noticed that the thread has been made a sticky, so it's at the top of the page.

I'll take care of updating the index in the first post with the information and linking to the appropriate message number.

 

<<- Can you test your LM35 on your GM328A transistor tester ?
I'm curious what it will show !
It will also show a transistor? or it will complain that is an unknown component ?

Won't show up as a transistor:

 

I received the response from Aliexpress:
But at least they responded and quite quickly so 1 point to them.
Hahahahahaha - eh well, someone had to try it, no? aaah, little chinese bastards.

 

You can report the info in my thread in the Marketplace forum.

I reported it here. You can make a post there and link to here or
copy everything is said here, including the pictures and post them there.
Is fine with me, if this information and experience is distributed all around.
And is a shame they are cheating like that.
The only reasonable solution is to change the package type of the sensor with a --distinctive-- shape, not to be easily "confused" with the TO-92 package. Is my advice and suggestion and recommendation and frustration all 4 in 1.

 

Won't show up as a transistor:

yes, that is what Im expecting as well, but... you never know until our friend from the other side of the globe will test it for me. mister @Jony130 don't sleep, you are needed once more -haha.

 

You are not the first, nor you will be the last, to have been scammed by Chinese supplier.
The old adage still applies; “If the price is too good to be true, then it isn’t true”.

Counterfeit devices are a major headache, not only for hobbyists, but for companies.

 

Can you also mount your LM35 into a transistor tester like mine (in the picture GM328A or similar)and take a read and a picture of it? Just to be sure.

Here you have:



This means that you bought fake devices. You bought NPN transistors repainted to LM35.
That's why I have not been buying components from Chinese online stores for a long time. Only from reputable suppliers (TME, Mouser, etc.).

 

This means that you bought fake devices. You bought NPN transistors repainted to LM35.

No it doesn't !!!
WOW !!! I didn't expect that reading at all !
Neither NPN nor PNP. It should have read " unknown component " !!! What the hell ? Oh boy... that's why is hard for the sellers to know what they are selling perhaps? Very strange that you have that PNP reading on yours.
Thank you very much for the reading !!! You are a light of sunshine.
WOW !!!
Now... I start to believe maybe mine are ... not so bad? Just because they read as NPN on mine and yours as PNP, it means they used some different schematic inside the chip? IF they have any kind of chip at all !!! Now I'm doubting my components as fake or damaged.
Because I really don't know how to test them at this point, giving your result there.
I need a more clear_decisive reading than this. I'm not telling you to do it, I'm thinking out loud what that test should look like?
Hmmmm...
Maybe yours are also "fake" as well, like mine here.
Also...these testers, sometime, they throw false readings. It's a good practice to test 2-3 times and if the result is consistent, especially now with this component, then your first reading is ok. If you got different readings than the one you presented, do tell me !
Like mister @dl324 showed the internal circuit in his post #26 and also confirmed my logic too.

I did obtain a decreasing value from my LM35's when I was increasing the temperature on their body ! Maybe because they are npn?
And yours are giving an increasing value when increasing the temperature on their body. Maybe because they are pnp ?
Hmmmm...
Maybe they are just simple transistors and they lie to us as having some complicated "chip" inside while all this time they are just simply bloody ordinary transistors? But sold as 10pcs with 5$ !!! while the rest of the ordinary transistors are 100pcs for 2$ !
Hmmmm...

 

You can make a post there and link to here

Done.

 

No it doesn't !!!
WOW !!! I didn't expect that reading at all !
Neither NPN nor PNP. It should have read " unknown component "

No, you are drawing conclusions too quickly.
Notice that my Lm35 shows on the component tester very low current gain (Hfe = 13 ) and a very large leaking current.
Also if I measure it using a DMM set on a diode tester I get the results that do not match the measurements of a good and working PNP transistor.

So for sure this is in a PNP transitor.

On the other hand, your device shows a very large HFE value and low leaking current typical for good NPN BJT.
Try mesure is using DMM seting on diode tester.

Like mister @dl324 showed the internal circuit in his post #26 and also confirmed my logic too.

But this schematic doesn't show the real silicon structure. So we cannot see parasitic structures shown by the component tester and DMM.

And yours are giving an increasing value when increasing the temperature on their body. Maybe because they are pnp ?

No, both NPN and PNP behave in the same way as the temperature increases.
And now my LM35 shows 216.7mV = 21.67°C and my DMM thermometer is showing 20.8°C, and 21.0°C by my ds18b20.

 

No, both NPN and PNP behave in the same way as the temperature increases.

No, mine is behaving inverse than yours because I test it. I can make you a movie if you dont believe me. If Im applying heat on the case, it will lower its voltage reading. I used a DMM set on the lowest setting 200mV and I could read it like this. When connected to one of the opamp inputs, because freely is giving me 0V.

Notice that my Lm35 shows on the component tester very low current gain (Hfe = 13 ) and a very large leaking current.

Yes, very good observation. I stopped when I seen mine is a NPN and didnt read the rest of the data. Very strange !
So you are saying your reading is ok even if is showing a PNP, because of those different values from a normal transistor... hmmm
You may be right, but I am still baffled.

 

No, mine is behaving inverse than yours because I test it. I can make you a movie if you dont believe me

This is not what I meant to say. But never mind.

So you are saying your reading is ok even if is showing a PNP, because of those different values from a normal transistor.

Yes, exactly.
On the other hand, yours is an ordinary NPN BJT.
You can even connect it like this and see it yourself by measuring Vbe and Vc voltage and comparing it with the ordinary NPN you have at your disposal (2N2222, BC547B).

 

OK, now I have a really radical suggestion, which is go to the website of the manufacturer of the LM35, and verify the connections to the device. What I think I see is the operation of an incorrectly connected device. And certainly that is possible.