Just forgot !
Read this and cry... heheheh
I was in a components store, and just to play with those fools I asked for 2N3055... They brought to me a TOSHIBA hahahaha... Then I said,
Dude, its FAKE !
Nooooo, it's NOT !
God... Toshiba do not manufacture this transistor since year 2000 !!
You're completely wrong... You BORN YESTERDAY... I know if the transistor is fake or not at first sight !
IT IS FAAAAKEEEEEEEEEEEE !!!! You don't know anything about transistors !!
Then I left the store
Read this and cry... heheheh
I was in a components store, and just to play with those fools I asked for 2N3055... They brought to me a TOSHIBA hahahaha... Then I said,
Dude, its FAKE !
Nooooo, it's NOT !
God... Toshiba do not manufacture this transistor since year 2000 !!
You're completely wrong... You BORN YESTERDAY... I know if the transistor is fake or not at first sight !
IT IS FAAAAKEEEEEEEEEEEE !!!! You don't know anything about transistors !!
Then I left the store
nando:
The capacitance test is probably the simplest and most portable you can do.
When we discussed hfe, it was the ability of a genuine transistor to maintain a high hfe (20-30) up to high currents. That test is not portable because you'd need to carry around with you the ability to drive 10 or 20 A into the part.
The cap test has its pitfalls though. For my MJ15003's fake parts had between 1500 and 2100 pf, while good parts were between 3400 and 4200pf.
I think instead of setting screening rules based on absolute capacitance, you'd be safer to bring a KNOWN good part along and compare relative cap. The fake should have about half the cap or so of the good one.
And you need to make sure youconnect the + of cap meter to Emitter for an NPN part and vice versa, so as not to forward bias the transistor. If your cap meter doesn't indicate its + lead you have to determine with a voltmeter.
PS. you cannot conclusively condemn the merchant who has Toshiba 2n3055's, since it's not unusual for semiconductors to float around in the market for 5 years, 10 years, or more.
And what exactly are you trying to accomplish by confronting the merchant with an accusation?
I would think that if you take your cap meter in there and get a bad reading, you'd say " I'm sorry, this part doesn't match my requirements, do you have any other batch?" He might then bring out some good ones. It's probably more useful than banning yourself from that store (and many others) forever.
Andy
The capacitance test is probably the simplest and most portable you can do.
When we discussed hfe, it was the ability of a genuine transistor to maintain a high hfe (20-30) up to high currents. That test is not portable because you'd need to carry around with you the ability to drive 10 or 20 A into the part.
The cap test has its pitfalls though. For my MJ15003's fake parts had between 1500 and 2100 pf, while good parts were between 3400 and 4200pf.
I think instead of setting screening rules based on absolute capacitance, you'd be safer to bring a KNOWN good part along and compare relative cap. The fake should have about half the cap or so of the good one.
And you need to make sure youconnect the + of cap meter to Emitter for an NPN part and vice versa, so as not to forward bias the transistor. If your cap meter doesn't indicate its + lead you have to determine with a voltmeter.
PS. you cannot conclusively condemn the merchant who has Toshiba 2n3055's, since it's not unusual for semiconductors to float around in the market for 5 years, 10 years, or more.
And what exactly are you trying to accomplish by confronting the merchant with an accusation?
I would think that if you take your cap meter in there and get a bad reading, you'd say " I'm sorry, this part doesn't match my requirements, do you have any other batch?" He might then bring out some good ones. It's probably more useful than banning yourself from that store (and many others) forever.
Andy
General package appearance will be your first clue, and the manufacturer.
Yes, but just to add some irony to the situation -- for some transistors the fakes have a nicer looking package and more legible markings than the real ones.
For those who need a reference range for Cbe values, here's what I tested on a few transistors ( in nF, 5 devices of each ).
MJL4281
11.45
11.03
11.81
11.07
12.08
MJL4302
10.94
10.95
10.94
10.99
10.92
MJ15004
3.67
3.62
3.66
3.68
3.66
MJ15003
3.82
3.65
3.98
3.87
3.84
MJ21193
8.40
8.39
8.40
8.43
8.29
MJ21194
6.42
6.03
5.91
6.40
6.05
MJ21294
13.18
11.73
12.14
12.55
12.62
Looks like every audio power transistor that came out after the 15003, has grossly greater capacitance. Must be the newer technology, higher hfe, and better SOA that's doing this to the Cbe, by imposing a larger die size. Eva did say at one time that Motorola devices have obscenely high cap.
Andy
MJL4281
11.45
11.03
11.81
11.07
12.08
MJL4302
10.94
10.95
10.94
10.99
10.92
MJ15004
3.67
3.62
3.66
3.68
3.66
MJ15003
3.82
3.65
3.98
3.87
3.84
MJ21193
8.40
8.39
8.40
8.43
8.29
MJ21194
6.42
6.03
5.91
6.40
6.05
MJ21294
13.18
11.73
12.14
12.55
12.62
Looks like every audio power transistor that came out after the 15003, has grossly greater capacitance. Must be the newer technology, higher hfe, and better SOA that's doing this to the Cbe, by imposing a larger die size. Eva did say at one time that Motorola devices have obscenely high cap.
Differences in package "look" can and often do occur as a result of devices being made in different periods or different mfr. plants by the same manufacturer. IMHO, not very wise to use that for screening.General package appearance will be your first clue, and the manufacturer.
Andy
Ok, ...I'm getting e-mail from people asking for specific part number Cbe values...
1.
What I posted is what I had on hand. I may be able to find others at work, but I can't promise anything.
If anyone else has common audio power transistors available, then maybe they can post Cbe on what they have.
Perhaps we can make a Wiki with this info.
2.
No, there is no complementary to the MJ21294 (although ONsemi has keenly reserved the MJ21293 part number).
The MJ21294 is a dual-die device, two 21194 dies slapped together in parallel. It's in there just for comparison, and it indeed shows exactly twice the cap of the 21194. Complementary symmetry is not the only way to build amps. This device is for quasi-comp designs.
Andy
1.
What I posted is what I had on hand. I may be able to find others at work, but I can't promise anything.
If anyone else has common audio power transistors available, then maybe they can post Cbe on what they have.
Perhaps we can make a Wiki with this info.
2.
No, there is no complementary to the MJ21294 (although ONsemi has keenly reserved the MJ21293 part number).
The MJ21294 is a dual-die device, two 21194 dies slapped together in parallel. It's in there just for comparison, and it indeed shows exactly twice the cap of the 21194. Complementary symmetry is not the only way to build amps. This device is for quasi-comp designs.
Andy
Buy them from an ON distributor like Newark/Farnell. ON ships directly to the recomended distributors. It is highly likely the least amount of shipping/recieving and other interaction will yield genuine product... Or get samples directly off the www.onsemi.com ...
ECS21 said:pic of fakes motorola transistors
These devices seem very strange, because the manufacturing seems almost genuine On-Semi, including the shape and size of copper base and the bonding wires, but die size does not match MJ15024. Might they be rebranded lower power On-Semi deivces?
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
- Home
- Design & Build
- Parts
- Fake *******ING "MOTOROLA" Transistors