My Transistors, original or copy?

[Salas]

Originally Posted by jacco vermeulen

You sure your Mrs isn't a clone ?

Jacco you probably have watched Blade Runner way too many times over.

[jacco vermeulen]

Are you kidding.

Even today, i'd bang Darryl Hannah, Halle Berry (cat woman), Rebecca Romijn (x-men) and Milla Jovovich (5th element), provided they wear the outfits.
H, i'd even do the blue diva from 5th element, for free.
Without the dress, no f. way.

(Mr Hauer should wish he'd be a clone, i gathered he's jacking himself up at age 67 to make some Hollywood bucks again)

[unclejed613]

fake MOSFETS?, yes there are some out there.... just saw another post recently where somebody had a plastic TO-220 MOSFET that had been shaved and reprinted. he bought his fake MOSFETs from a vendor in hongkong (no big surprise there...)

when in doubt, a capacitance meter is your best friend. junction capacitances are usually published in the data sheet. with MOSFETs, the G-S and G-D capacitances are usually published (not sure if i've ever seen Cds published, but i could be wrong about that). same goes for bipolars, except the capacitances on the data sheet are published as Ccb and Cce or sometimes as input capacitance (Ccb) and output capacitance (Cce)

[Salas]

Originally Posted by jacco vermeulen

(Mr Hauer should wish he'd be a clone, i gathered he's jacking himself up at age 67 to make some Hollywood bucks again)

His best lines as a replica leader maybe best in his career, ''I have seen things you people wouldn't believe...all those moments will be lost in time like tears in the rain,,, time to die'' a blood tear drops on his rain drenched face and he switches off. Sci-Fi in its finest.

[Andy5112405]

Originally Posted by unclejed613

fake MOSFETS?, yes there are some out there.... just saw another post recently where somebody had a plastic TO-220 MOSFET that had been shaved and reprinted. he bought his fake MOSFETs from a vendor in hongkong (no big surprise there...)

when in doubt, a capacitance meter is your best friend. junction capacitances are usually published in the data sheet. with MOSFETs, the G-S and G-D capacitances are usually published (not sure if i've ever seen Cds published, but i could be wrong about that). same goes for bipolars, except the capacitances on the data sheet are published as Ccb and Cce or sometimes as input capacitance (Ccb) and output capacitance (Cce)

Has anyone got a KNOWN GENUINE IRFP244 to publish its COLD capacitance values. The datasheet shows the capacitances at 25V which my capacitance meter cant measure. I bought 100 of them from a guy in the UK but I've no idea where he got them from. I could break one open to have a look but has anyone got a photo of the innards of a REAL one ?

[unclejed613]

Originally Posted by Andy5112405

Has anyone got a KNOWN GENUINE IRFP244 to publish its COLD capacitance values. The datasheet shows the capacitances at 25V which my capacitance meter cant measure. I bought 100 of them from a guy in the UK but I've no idea where he got them from. I could break one open to have a look but has anyone got a photo of the innards of a REAL one ?

if you are looking for genuine devices, i recommend ordering some samples directly from IR. i got some samples from ON of some transistors i plan on using, and i have 5 of each device (PNP and NPN of course) to test. i can get capacitance readings from them and determine whether a device i buy from a supplier is a fake or not. samples are usually free, and you know they came from the manufacturer or a trusted (by the manufacturer) distributor.

it's not difficult to measure at the published voltage. apply the 25V to the junction through a 1meg resistor, and put a 1uf cap in series with the cap meter probe for isolation. the amount of capacitance error the series cap will make isn't enough to worry about. just remember it will be a couple of percent low; junction capacitances are usually within +/-10 percent or so. if the reading is 15% or more off consistently (since you have a batch of devices) i'd question their authenticity. with bipolars, i've seen not only the capacitance readings be wrong by 50% or more, but the Ccb and Cce capacitance ratio be really wrong. with good devices, if it's a 3:1 ratio, i've seen it close to 1:1 on fakes. i'd have to do a bit of testing with MOSFETS to establish a baseline, so when it comes to MOSFETS, the data sheet is where to look. but the capacitances also give a clue to the relative die size. the capacitance is roughly proportional to the surface area, but it's also inversely proportional to the thickness of the gate insulator. i've seen a relatively simple curve tracer design using a binary counter and op amp to do the gate voltage stepping.... i'm really thinking of building one (actually two, one for where i work, and one for stuff i do at home). of course it would work at a single drain voltage rather than stepping the drain voltage also, but it might be worth a try.

[Andy5112405]

Can you experts cast your eyes over these.

Are the counterfeitters getting better ?

This is an example of a batch of over 100 IRFP244s that I bought from a vendor in the UK.

This is what IR say they should look like.

This is what I have got.


Is it me or is the typeface out of line ?

[SY]

Batch codes are often printed using a different print head than the company logo, since the logo artwork stays the same from run to run. So the registration even on a real device may not be perfect, depending on whether they use a single or two head printer, or a movable batch number wheel windowed into the logo plate.

[Andy5112405]

As the label is recessed, I find it difficult to believe that these have had their part numbers ground off to make way for re-badging.

I could really do with a circuit to put them to test and compare them against their SOAR.

[poynton]

.....it's just as easy to post pictures using the attachment facility provided by the forum ......

...... Photobucket images disappear after a time, attachments don't !! .....


.