Electronics > Projects, Designs, and Technical Stuff

Looking for transistor data: ETD41-035

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torch:
Comparing the datasheets, the ST901T seems a little less robust than the MJE5740 in terms of maximum voltages and currents (although with a higher power dissipation). However, since I don't have a datasheet for the original ETD41-035, it may well be just fine. I guess the only way to find out is to try them, so I ordered some.

And just for $!+$-and-giggles, I ordered some of the supposed original from that Chinese vendor. Maybe they really are surplus NOS genuine Fujitsu transistors.

If one or the other seems to work well in the TCI I'm repairing, then maybe I'll risk desoldering one of the originals from the known-good TCI and try comparing the three in some sort of test circuit. (In which case, I'll probably be back asking for advise in designing the test circuit  ;D).

torch:
UPDATE:

The ST901T "works a treat" as Dave would say. In fact, it works better than the original. I forgot to save a screenshot from the scope, but the pulse is much broader and the spark produced is much stronger. The known-good unit craps out at about 1/4" (this is a waste-spark system, so that is in addition to the spark under compression in the opposite cylinder). With the MJE5740 installed, the spark barely jumped a 1/8" gap (in free air, so that would be less under compression. No wonder ran so poorly.) But equipped with the ST901T I had it up to 1/2"! (It was still strong, but I did not want to open the gap further for fear of stressing the coils and wires with the excessive voltage).

Thanks to all who chimed in, especially mikerj and MagicSmoker.

(If anyone ever does come across a datasheet for the ETD41-035, I'd still be curious to see it and compare to the ST901T one.)

MagicSmoker:
Heh, I'm glad I was of some help here, but I demur to mikerj for providing a specific solution!



torch:
Don't sell yourself short -- you told me why the other one didn't work and helped me learn something.

There are many forums on the net where people asking questions are met with derision. I appreciate that people here took the time to help me out. This forum is great that way.

Seekonk:
Thanks for pointing to the ST901T, a good data sheet to save.  I had a Toyota Supra a long while back and the ignition module failed.  Went to the dealer and without even looking it up quoted like $200.  I thought to myself....... Hey, who won the war.  Tore it apart and everything was buried under some sticky silicone goop.  Noted my three points of interest and brought wires out.  That was touchy soldering under that goop.
Had a bunch of 700V small power NPNs.  I think the first effort used four in a darlington.  That ran for about 2 minutes before smoke.  Next used six and that ran for over 40K miles till I sold the car.  I know the next guy ran it another two years.

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