All about Chinese TO-92 transistors

Thread Starter

Willen

Joined Nov 13, 2015
313
Hi,

I had bought few pieces of Chinese BC547, some 2sc9014, some 2sc9018 from nearby repairing shop. I love analog electronics and love 'Transistors'. Almost all Chinese TO-92 packages looks pretty similar, looks pretty bad and made by a very lazy and careless machines (example uploaded below). I had bought some pieces almost 5 to 7 years ago and now their leads converted into rusty piece of wire. Now I stored them into a bottle of full of engine oil, to stop growing the oxide :). Some people around discussion forum say they use same transistor chip (die) and just label different part numbers. I can see some Chinese site sell hundreds of transistors at few couple of dollar. So the main curiosity is if someone have focused on these types of transistors and tested in detail or experienced then I want to read about: (I am just a hobbyist and maybe cannot find what is wrong with them going on.)

  • Does the BC549 really work as a very low noise transistors?
  • Does the S9018 have nice gain even around its max rating of 1.1GHz transient frequency like genuine?
  • Does the MPSA18 have hFE of around 1,000 or more?
  • Does the MJE1300 have 0.1A at 400V and MJE1303 have 0.4A at 400V capability?
  • Does the 2n2222 have 0.8A capability and really different than BC547 or 2N3904?
  • Does the 2N5087 have really very low noise features?
  • Does the 2sk117 have really ultra low noise performance?
 

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SamR

Joined Mar 19, 2019
3,405
Generic! No Provenance! No Product Datasheet! They are what they are, cheap (both figuratively and literally)! Not that I've done any rigorous testing on them, but they do seem to work. Much better than the Generic ICs from china.
 

dl324

Joined Mar 30, 2015
12,871
I had bought some pieces almost 5 to 7 years ago and now their leads converted into rusty piece of wire. Now I stored them into a bottle of full of engine oil, to stop growing the oxide
I have transistors acquired in the 70's and none of them have any corrosion.

I have some static sensitive opamps and CMOS IC's from that era that were stored in black antistatic foam and have lead corrosion.
 

SamR

Joined Mar 19, 2019
3,405
Even main source through hole components have magnetic ferritic legs these days. But, at least they are tinned. I also have components from the 70's that are impervious to rust even here on the extremely humid and salty coast. Some of the transistor even have stainless steel cases instead of aluminum.
 

DickCappels

Joined Aug 21, 2008
7,426
A couple of years ago I had to throw out about 100 2N3904's because of extreme corrosion on the leads. They were completely useless even after scraping down the leads with a sharp knife.

They were from a time when I lived in the United States and regularly bought parts from the likes of Mouser and Digikey -no eBay. Well, they were cheap enough even from U.S. vendors but it hurt to toss them.
 

Audioguru again

Joined Oct 21, 2019
3,173
  • Does the BC549 really work as a very low noise transistors?
  • Does the S9018 have nice gain even around its max rating of 1.1GHz transient frequency like genuine?
  • Does the MPSA18 have hFE of around 1,000 or more?
  • Does the MJE1300 have 0.1A at 400V and MJE1303 have 0.4A at 400V capability?
  • Does the 2n2222 have 0.8A capability and really different than BC547 or 2N3904?
  • Does the 2N5087 have really very low noise features?
  • Does the 2sk117 have really ultra low noise performance?
A BC549 made by Philips has low noise (see its datasheet). I used many of them when I worked for Philips.
An SS9018 made by Fairchild has a typical cutoff frequency (gain=1) of 1.1GHz (see its datasheet).
An MPSA18 made by Motorola (now called ON Semi) has a typical hFE from 500 to 1500.
For the other transistors see their datasheets.
I never buy cheeep junk from ebay and the other cheap places and have never had a problem with transistors.
 

dl324

Joined Mar 30, 2015
12,871
A couple of years ago I had to throw out about 100 2N3904's because of extreme corrosion on the leads. They were completely useless even after scraping down the leads with a sharp knife.
The corrosion works its way into the encapsulation and damages bonds wires and the semiconductor itself. I used one of the IC's I had with corroded leads (after repairing some of them) because I didn't have any others handy and didn't feel like buying more (it was a CD4510 and I've since decided that CD4029 is better). It worked for the test circuit I breadboarded, but it's days are numbered.
 

MisterBill2

Joined Jan 23, 2018
8,745
The corrosion works its way into the encapsulation and damages bonds wires and the semiconductor itself. I used one of the IC's I had with corroded leads (after repairing some of them) because I didn't have any others handy and didn't feel like buying more (it was a CD4510 and I've since decided that CD4029 is better). It worked for the test circuit I breadboarded, but it's days are numbered.
The cheap steel leads do rust, but some of the automated assembly machines could handle them very well. And for some consumer junk stuff they did not need to last more than ix months.. If they got that shot of "funny oil" after assembly then they could last a while longer. And the big thing is that really poor quality steel is a lot cheaper than any quality of copper.
 

anniel747

Joined Oct 18, 2020
1,041
The cheap steel leads do rust, but some of the automated assembly machines could handle them very well. And for some consumer junk stuff they did not need to last more than ix months.. If they got that shot of "funny oil" after assembly then they could last a while longer. And the big thing is that really poor quality steel is a lot cheaper than any quality of copper.
It' fishy that the "funny oil" as you say attract varmint.
 
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