I found that picture trying to search what you were describing.
I didn't see the C E O note in the earlier post.
Thanks for the explanation and the test idea. I'll give it a try.
I didn't see the C E O note in the earlier post.
Thanks for the explanation and the test idea. I'll give it a try.
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Some comments - alternative transistors might be 2N4033 (the NPN complement is 2N3019) (80V) or 2N5680(PNP) (complement 2N5682) at 120V which may still be available from Farnells, but you will need to add a heatsink as these are plain TO5 cans.
Indiana - I would recommend BD139/BD140 for these drivers but test the fT. Over here ST sold BD139/BD140's without an ft spec, and I didn't trust that either until I'd measured a few. Can be done at 1MHz - gain should still be around 100 (at least over 50) rather than <10.
Also isn't the 40411 a selected 2N3772 - actually worse than a (selected) 3055 as its ft is only 200kHz. Things like 40363/40636 were selected 3055's AFAIK.
Indiana - I would recommend BD139/BD140 for these drivers but test the fT. Over here ST sold BD139/BD140's without an ft spec, and I didn't trust that either until I'd measured a few. Can be done at 1MHz - gain should still be around 100 (at least over 50) rather than <10.
Also isn't the 40411 a selected 2N3772 - actually worse than a (selected) 3055 as its ft is only 200kHz. Things like 40363/40636 were selected 3055's AFAIK.
A lot of old 4xxxx devices were selected 3055’s. The reason the 40411 fT is only 200kHz instead of 800 is because higher vceo capability often comes at the expense of speed. A device may be good enough to be called a 40411 (vceo of 90) but fail an 800 kHz fT spec for the 3055. What to do with them? Bin them as another type - Prseto! You’ve got 40411s to sell.
777, you said on another thread you are working on a bass amp. These amps do not need 7000-20000 hz response. a 3 mhz Ft transistor like TIP31c/32c would be adequate for bass instrument drivers. those are still BCE, unlike the TO5 EBC transistors I quoted previously.