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Old 30th November 2007, 11:38 PM   #1
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Default Using this test gear to detect fake power transistors ?

Hello

I may buy this tester; M3 Semiconductor Analyzer Kit

From;

http://www.m3electronix.com/features.html

I would use it for VBE and HFE and leakage test.

How can I use it to detect fake power transistors ?

Thank

Bye

Gaetan
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Old 30th November 2007, 11:50 PM   #2
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Location: Canandaigua, NY USA
If the small signal specifications of the fake are ok, then you can't. I don't know if it will do high current tests, but I'd expect that's where the fakes will have problems. For small low power parts, it might do fine, but IMO that's where the fakes have the best chance of being ok. Not sure there's a good way to detect a fake unless some spec is obviously outside the published window.
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Old 1st December 2007, 12:01 AM   #3
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Hello Conrad

Do you know a simple test gear to check bjt power transistor at medium or high current ?

Thank

Bye

Gaetan
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Old 1st December 2007, 12:38 AM   #4
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Well, I cheat. I use a big old Tek tube-type curve tracer. The newer ones are way out of my price range. The time-honored method is to simply set up a power supply and a low value resistor from collector to emitter, ideally with a current meter, then use another supply and a pot to apply a current to the base. You just monitor the collector current and figure the gain point by point. The device has to be on a good heat sink with grease and maybe a fan. At the absolute low end, it could be done at low powers with a couple "wall warts" and some cheap import meters. If you look at the data sheet, there will be a safe operating area (SOA) chart. The device should survive anywhere inside the continuous part of the chart. Doing the pulse measurements is much more difficult. Still, if a fake passes all the tests, it's still a fake! There's frequency response to consider, the rise and fall times, and the capacitances, all of which are a pain to measure properly. There's also the matter of "typical" parameters that aren't guaranteed. These might be a bit out on a real device, so how do you evaluate them on a fake? How would I identify a fake if I were really serious about it? I'd carefully disassemble the device, take a micro-photograph of the die, then email it to the manufacturer and ask, "is this one of yours, or an unauthorized fake?"
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Old 1st December 2007, 10:37 AM   #5
AndrewT is online now AndrewT  Scotland
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If the fake, that one has already paid for, performs as well as the original, then what's the problem?
We cannot take our money back from the fakers!
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regards Andrew T.
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Old 1st December 2007, 10:39 AM   #6
bigwill is offline bigwill  United Kingdom
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Quote:
Originally posted by AndrewT
If the fake, that one has already paid for, performs as well as the original, then what's the problem?
They have won
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Old 1st December 2007, 02:17 PM   #7
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Default Dear Gaetan.... better not to worry too much about that


You can be free from the fake ones not buying them..... it is very easy this way.

The fake ones are always the most famous, more used, last new models and "guaranteed" units.... those MJ15004..... 2N3055..... TIP35.... 2SC2922 (sanken)..... 2SC5200 (toshiba).... those new MJ21XXX people loves to use.

Into Sanken models, you have the "big shot"... the second position (the last year big shot)... the third and the fourth.... search for the fifth position and buy it...or even more distant from that.

Difference is small..... one can hold 16 amperes...the other 15... the third will hold 12 amperes and the fourth will work with 10 amperes....do not go to fashion transistors....no one is producing fake BD139..... they are not respected.... people think MJ340 and MJ350 is better...so..... you will find MJ340 and 350 fake.

People that use to produce fake transistors, will not spend time with BD139.... no one will buy the old folk.

With the same performance compared with BD139 you may have 1000 different transistors...sligthly different...but not fashion units...go to them!

regards,

Carlos
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Power supply; ripple, filter, noise, stability and the use of capacitance multiplier... Portuguese and English; https://www.youtube.com/watch?v=sSm0ku1eIgg
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Old 1st December 2007, 02:28 PM   #8
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Default Also dear Gaetan, in my country we do not use to buy from internet

We do not send bank data using computers, no credicard using computers...we do not trust...only few people use to do that.


We have shops, downtown.... we go there...we know the owner, we talk with them.... we know their family, son, daugther also work into the shop... the dog is there too....we watch the man into the eyes when we buy something there...and we ask if they are fake or not.

We do not return if the transistor is fake....we start to talk to friends..we burn the guy's image on fire of the dirty fast judgement!.... no one will buy there anymore...there are 5 or 6 shops downtown, audioholic and corrective maintenance personal are not more than 50 into this 3 million folks town...we know all them..... if we open our big mouth...boooom!

So...because of that.... they buy from original manufacturers.... nothing to buy with special price....negative to buy from lower price people.... so.... they are safe from fake ones, those offers of low price are fast dennied.... it is rare to find fake ones in brazil.

We had fake toshibas.... used to television Horizontal....hehe... the shop that sold, in São Paulo, our main town, is already closed... news about dirty things runs faster than ligth here.... i love this behavior of my people.... they open their big mouthes and they spit all the dirty out...they trow the dirty into the ventilator! (fan)

The electronics supply centers in this country, the main ones are in Rio de Janeiro and São Paulo, the two main towns in this country.... Republica do Líbano into Rio de Janeiro and Santa Efigênia in São Paulo.... the whole street is dedicated to parts, electronic things, speakers, transformers and so on...from there the parts travel to the states...so...it is easy to track the source and burn the image....as people is easy to be detected, they feel afraid from the people's reaction...silently (silence only to the dirty fake distributor guy) they do not buy anymore..... one day the guy will perceive have to close the business.... happened many times...people do not do that anymore.

regards,

Carlos
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Power supply; ripple, filter, noise, stability and the use of capacitance multiplier... Portuguese and English; https://www.youtube.com/watch?v=sSm0ku1eIgg
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Old 1st December 2007, 09:08 PM   #9
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Hello Carlos and everybody

After few emails exchange with the seller of that M3 Semiconductor Analyzer Kit and after reading all your reply, I decided that I will not buy that M3 Analyser.

There is nobody near my home who sell parts, and going to the city to buy them are quite far and costly in bus, so I have to order, most of the time, by mail, but I did have mail problems so I allway try to buy all I need wen I go to Montreal, but the last electronics store did sell me fake MJ15003 and MJ15004.

I've just order a good bunch of transistors and some silver mica caps from Mouser.com, but I don't have a credit card so I allway paid with a money order. They use Fedex for shipping but it cost $25. of flat rate shipping, I will see if Fedex are a good carrier.

Thank

Buy

Gaetan
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Old 1st December 2007, 09:15 PM   #10
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FedEx should be fine. Never ever use UPS to Canada, as they add all kinds of costs by using third party brokers. I hate to pay what shipping costs these days, so I try to order lots of stuff on each order.
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