"Jeff Liebermann" wrote in message
...
On Sun, 17 Apr 2011 21:04:28 -0400, "Barry" wrote:
Welcome back. You were missed.
Thanks, Jeff
To someone who understands these specs, and knows which ones are
critical
to the application, this is all that is needed. To someone who wants
to
buy a NTE "drop-in" part, I suggest you go to one of the Asian parts
suppliers who advertise that they can get the original part.
NTE does not list a substitute. I've dealt with some of the "obsolete
parts" vendors. Figure on about a $200 minimum, whether you want 1
part or 100 parts. When I once absolutely had to buy from one of
these vendors, the negotiation to delivery ordeal took about 4 weeks.
I found a part rated at 1000 BVces, 450 BVceo, 30 amps, and 250 watts.
It has a f(sub)T of 10 MHz and a Vce(sat) of 2 volts at 20 amps.
Now YOU tell me if this will work or not... Both Mouser and Digi-Key
found this part.
Barry WA4VZQ
To begin, it is really a conventional NPN, not an IGBT. You have to
learn
that Digi-Key and Mouser are not perfect in their searches. I had to
relax
the specs to find the part - like using 20 amps rather than 30. However
when I checked the datasheet, the part was really rated at 30 amps. Go
figure...
I thought this was going to be easy. I was wrong.
From the original data sheet at:
http://www.datasheets.org.uk/T30G40*-datasheet.html
With a saturation voltage of 2V at 30A, it's certainly an IGBT.
Look at the very high base current. This is how the low Vce(sat) is
obtained. Also note the Vbe(sat).
Lots to chose from on Digikey, but not in the package shown. I'll guess
the package is a TO-264 or TO-3PL
It's a TO-247 case. Actually starting the search with the package style,
in my opinion, is a poor place to start. You need to match the critical
specs first. In this case, high breakdown voltage, high current, and low
saturation voltage were the critical specs to match first.
www.fairchildsemi.com/products/discrete/pdf/to264.pdf
I couldn't find a close match with the correct package on Digikey or
Mouser. All the TO-264 package devices are higher power, with higher
saturation voltages. Some compromises will need to be made here.
To avoid all the suspense, look at an OnSemi MJW18020. OnSemi even
has Spice2, PSpice, and Spice3 models as well as a Saber model for it.
While Digi-Key does not stock them, Mouser has them at less than $6 a
pop.
For those that have never used the Digikey parts search, it's best to
explain how to use it by example. Start here for discrete IGBT's.
http://search.digikey.com/scripts/DkSearch/dksus.dll?Cat=1376382&k=igbt
Under "Package", highlight "TO-264".
Hit the "Apply Filters" and notice how the choices are reduced.
Notice that under "Ic Max", there's no choice for "30A". Pick "40A"
and again hit "Apply Filters". You should see 2 devices listed,
neither of which is suitable. Try some of the other TO-264 package
variations for more trial and error. Eventually, it finds:
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=IXSK40N60BD1-ND
in a TO-264AA package, which is not an exact substitute, but might
work. Someone please check my guesswork. If you look at the data
sheet, it shows a gate instead of a base lead, but if you read the
fine print, it's really an IGBT, and not a FET.
--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
I know we are dating ourselves here, Jeff, but bipolar transistors are
much like vacuum tubes in that triodes are triodes and with some
changes in circuit values (and rewiring, of course) just about any triode
can be made to work in a pinch. Actually bipolar transistors generally
are even easier to substitute than vacuum tubes.
Do you have an NTE replacement book handy? Notice how many
transistors can be replaced by the NTE123AP. Look up the specs on
a 2N3904. The 2N3904 is far cheaper ($0.07) than the NTE part and can
probably be used anywhere the NTE123AP ($1.25) can be used.
73, Barry WA4VZQ
One other thing when using the Digi-Key or Mouser search engines...
If you need a part with, say, a BVceo of 100 volts or more, you can
highlight 100, 150, 200, and 250 volts at the same time. ?This will
usually speed up the search. I do like Mouser's engine in that it
immediately tells you that no part is available with that specification,
while Digi-Key waits until you do the filtering - not knowing which
spec cannot be met.