"Gareth Magennis"


With regards me testing these TIP's with my dodgy tester, I may well be
wrong about them being dodgy, I understand fully what Phil has been
saying, and it is entirely possible he has been correct all along. Thing
is I reacted to the way he was reacting, maybe that wasn't the smartest
thing to do, I can normally tolerate him a lot better.
I apologise for that, Phil, it shouldn't really have gone that way.


** OK.

I stated from the very outset that I knew a Hfe reading from this tester
on a Power Transistor was "meaningless", but this seems to have been
largely ignored.

** As I explained repeatedly, the Peak meter uses Hfe readings to determine
C and E.

So if it *cannot read Hfe reliably* for a particular BJT - then it CANNOT
always get C and E right.

There is no magic way to determine C and E with certainty other than break
down voltage tests ( the CE junction should go at about 12V while the CB
one ought to be higher) - with only an internal 5V supply, the Peak tester
cannot do this test.



In fact the reason I knew of this was because of previous posts by Phil
probably a couple of years ago now on this thread.

Thing is though, all 4 replacements read OK at a healthy Hfe of 60 - 70,
where all 4 of the other batch read pretty much zero, most probably
because of a confused pinout diagnosis from the tester, or maybe because
they really are dodgy at the lower extremities of operation, where they
would not be operated anyway.

I did later construct a quick test rig on 2 of these old "dodgy" TIP35C's
which showed, at around 0.5A collector current, an Hfe of around 49, and
the correct pinout.


** Halleluiah.


..... Phil