Cursitor Doom wrote:
Hi all,

Is there any reliable method for testing parts for authenticity? I just
bought a bunch of LM317T variable voltage regs off Ebay (from a dealer
with a solid rep, admittedly - but they could themselves have been
fooled) and would like to know if they're genuine or not, as a quick
search on the net showed there *are* fake LM317s around.

in my experience with fake parts, they usually have nothing to share
with the real one.
Usually they bother to fake expensive parts (like out of production mosfets
or BJT for example that cost many $$ a piece).
I have fake mosfets that really are inexpensive switching high voltage
parts, even the pinout is different, so it's easy to spot.
BJT are usually much different dies, a quick curve tracer inspection
shows them.
I guess that nobody would really bother to fake an LM317, it's
inexpensive and still in production, so why even think about that?
The only gain would come from marking as LM317 some empty TO-220 parts,
and that would be easy to spot :-)


Would one be safe to assume that any fake part would not be capable of
performing at the maximum levels claimed by genuine manufacturers in
their datasheets? For example, the 317 is claimed to be good for 1.5A,
but if mine burn up at say 1.3A, is that a clear indication that they're
fake?

read the datasheet, most of the values are "typical".

Best regards
Frank IZ8DWF