Hello Everyone,
5 or 6 years ago I bought a bunch of these transistors and they were eating the dust ever since. Recently a project came up where they would come handy but when I took them out of their original packaging I was shocked. All of them has ST logos but they look weird. Some of the labels have a significant tilt or off the middle and no clearance left from the edge and the TIP41 has 3 entirely different looking variants as if they have come from different places.
Could you please have a look and tell me if any of these could be genuine or alternatively I would appreciate if any of you could send me photo of a genuine one.
Unfortunately I can't do measurements as my oscilloscope's dead and the replacement is coming on the next week or after.
Many thanks in advance for your replies.
5 or 6 years ago I bought a bunch of these transistors and they were eating the dust ever since. Recently a project came up where they would come handy but when I took them out of their original packaging I was shocked. All of them has ST logos but they look weird. Some of the labels have a significant tilt or off the middle and no clearance left from the edge and the TIP41 has 3 entirely different looking variants as if they have come from different places.
Could you please have a look and tell me if any of these could be genuine or alternatively I would appreciate if any of you could send me photo of a genuine one.
Unfortunately I can't do measurements as my oscilloscope's dead and the replacement is coming on the next week or after.
Many thanks in advance for your replies.
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I would never risk using fake devices and would bin them.
I always buy from reputable dealers like Farnell and RS Components.
I always buy from reputable dealers like Farnell and RS Components.
ST has multiple fabs and assembly houses, and each one has its own unique packaging and marking protocols. It's documented in their literature. All of those devices look like they fall within the normal range. Measure Vbe (on diode check on your DMM) and base-emitter capacitance if you can. If they measure close to each other you are probably good to go.
And faking a TIP41 is sort of like launching an ICBM horizontally. You could, but why would you want to? If a counterfeiter would take the trouble to put something together that looks like a TO-220 transistor, he may as well mark it with a type number that can be sold for more than a TIP41.
And faking a TIP41 is sort of like launching an ICBM horizontally. You could, but why would you want to? If a counterfeiter would take the trouble to put something together that looks like a TO-220 transistor, he may as well mark it with a type number that can be sold for more than a TIP41.
The Morocco ones are fine. The China ones are not as good. It is difficult nowadays to judge if a product is genuine or not, because every manufacturers tried to lower production cost by moving the production to countries where there are problems with not only skill and technology but....
I think TIP41/42 is not a good device for high-end. For mid-end application I think it is sufficient to know if the Safe Operating Area (SOA) is good enough for your application. If you use it as a driver of normal amplifier (Vce), I doubt you will have a problem. But if you push it near the boundary of it's SOA (power, class-A amps) according to datasheet, I doubt you will have NO problem 😀
Thanks wg_ski. I just checked the hFE and C->E capacitances on the 3 different TIP41C.
I would list them by their unique IDs/dates:
Morocco --> hFE 77, 119.4pF
Mar 712 --> hFE 62, counting up from 60pF
CHN 933 --> hFE 68, counting up from 60pF, stops at 104pF after 5 mins
What do you think?
While you were writing your comment I was browsing Mousers list for replacement transistors. I think I put an order on 10x each and we'll see.
Thanks again.
I would list them by their unique IDs/dates:
Morocco --> hFE 77, 119.4pF
Mar 712 --> hFE 62, counting up from 60pF
CHN 933 --> hFE 68, counting up from 60pF, stops at 104pF after 5 mins
What do you think?
While you were writing your comment I was browsing Mousers list for replacement transistors. I think I put an order on 10x each and we'll see.
Thanks again.
Jay, I think I'll be within the SOA with my design. Just in case, what transistor would you replace them to? (class A + class AB amp) Thanks.
As far as I remember, there is no similar transistor to TIP41. For output device, of course you don't need to replace with similar device. If this is in driver stage, and if 3A device (instead of 6A) is sufficient, I prefer the younger brother TIP31.
BD241 is equal to TIP31. BD249 is 25A so is much "stronger" than TIP41. I don't know if between BD241 and BD249 there is one that is an equivalent of TIP41.
But I think the point is how to make use what you have already on hand, right? I myself have lots of BD911/BD912 TO-220 pairs but I have no idea how to make use of them because they just don't sound good.
Thanks for the advice, Jay. Yeah, I do prefer use up the ones I already have first, but then I'll certainly give a try to the BD249. 25A is really magnitudes above that but I don't mind, as long as it serves the purpose: amplifies. At this point I build amplifiers only for myself (no high quantities) so even if I don't need all that performance it still fits the project box... 😉
Musically correctness is a function of transistor linearity. Those transistors are indeed linear, but with 3MHz, it is hard to compete with faster transistors.
My favorite transistor, Sanken 2SC4466 is not only musically correct, but it is also fast (I think 20 or 25MHz).
Like the guy in Africa, I'd test for Iceo before throwing out transistors.
Put medium voltage on collector , short b & e, put dvm ma scale in series with 47k resistor, and DC supply. I use 36 v myself since I have some printer/fax/copier power supplies at that. If it leaks too much , pitch them. If not they might be real. A rated voltage supply of course would be better, but 60v & 80v supplies are hard to come by. The amp on my bench has 80v rail, I think I used that for Iceo test once.
Put medium voltage on collector , short b & e, put dvm ma scale in series with 47k resistor, and DC supply. I use 36 v myself since I have some printer/fax/copier power supplies at that. If it leaks too much , pitch them. If not they might be real. A rated voltage supply of course would be better, but 60v & 80v supplies are hard to come by. The amp on my bench has 80v rail, I think I used that for Iceo test once.
Hehe... from looking at the schematic (visually), I think it is very low bias, so not going to be good enough for me. And not many people will be sold on the idea of musical correctness 😀
Thanks wg_ski. I just checked the hFE and C->E capacitances on the 3 different TIP41C.
I would list them by their unique IDs/dates:
Morocco --> hFE 77, 119.4pF
Mar 712 --> hFE 62, counting up from 60pF
CHN 933 --> hFE 68, counting up from 60pF, stops at 104pF after 5 mins
What do you think?
While you were writing your comment I was browsing Mousers list for replacement transistors. I think I put an order on 10x each and we'll see.
Thanks again.
None of them seem out of family. But B-E capacitance is more telling, because it is the most consistent on any given device type. That's the one I compare to known good.
What is the end application - driver or output? As outputs on rails of less than +/-25V they work fine -and in that service I wouldn't spend money on something "better". They are not the best drivers in an EF2, but in an EF3 you mat want a slower part rather than some 50-100 MHz device in the 2nd stage.
wg_ski, thanks for the thorough reply mate.
Morocco --> 255pF
Mar 712 --> 924pF
CHN 933 --> 886.7pF
What do you think?
2xClassA driving a ClassAB, so both.
The rails for this project are +/-10V so I guess it should be fine.
Morocco --> 255pF
Mar 712 --> 924pF
CHN 933 --> 886.7pF
What do you think?
2xClassA driving a ClassAB, so both.
The rails for this project are +/-10V so I guess it should be fine.
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With +/-10V rails, you could probably get away with just about anything and have it not blow up. Including "fake" 2SC5200's if you ever get burned with some of those.
I've checked my stash of TIP41/42's, and I get a range of 200-ish pF for ON Semi, 200-ish for ST (no fab house marking - they are old pulls), 600-ish pF for RCA which were NOS from the 80's, and almost 700 pF for new Fairchild. Very consistent within each batch but it is clearly just a generic spec transistor.
I've checked my stash of TIP41/42's, and I get a range of 200-ish pF for ON Semi, 200-ish for ST (no fab house marking - they are old pulls), 600-ish pF for RCA which were NOS from the 80's, and almost 700 pF for new Fairchild. Very consistent within each batch but it is clearly just a generic spec transistor.
wg_ski, thanks for the tips and for looking into it, I'll probably use them all up in my current project. 🙂
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