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Old 20th September 2002, 08:35 PM   #1
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Default Need Help ID'ing Transistor

I'm trying to properly identify a Transistor. The transistor I need to replace is marked: BD140.

I cross-referenced it at NTE, and it comes up with 2 NTE replacements(NTE185 & NTE374) both PNP.

The search matched BD140 to NTE374 and matched BD140-10 and BD140-6 to NTE185.

So, I'm assuming the correct one is the NTE374 since the transistor did not have a -10 or -6 next to it. I just want to be sure to get the right one.

Thanks for any help.

Tom
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Old 20th September 2002, 09:15 PM   #2
haldor is offline haldor  United States
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Hi Tom,

Be aware that NTE substitutions are often marginal, performance wise. If the paramaters of this part are critical to the circuits operation I would try and find the real part.

Got burned by some NTE FETs once, never again.

Phil
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Old 20th September 2002, 09:28 PM   #3
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Does that mean that NTE transistors are unreliable or are they just not the same quality as the originals? I'm asking this because I was just about to order some bd139,bd140, bd546 and a few others from Mouser and all they have is NTE.
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Old 20th September 2002, 09:30 PM   #4
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Another question that I just thought of. Are the bd140's at MCM Sankens', if so are they any better? They are more than half the price of mousers' NTE brand.
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Old 20th September 2002, 10:55 PM   #5
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Quote:
Originally posted by KenP
Does that mean that NTE transistors are unreliable or are they just not the same quality as the originals? I'm asking this because I was just about to order some bd139,bd140, bd546 and a few others from Mouser and all they have is NTE.

No; I'm not assuming the NTE's are unreliable or poor quality. I just want to know if the right replacement is the NTE374 or NTE185 as described in my original post.
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Old 20th September 2002, 10:59 PM   #6
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Also, I can't seem to find a transistor that is actually marked BD140, only possible equivalents such as the NTE's.

It dosen't seem like this is a very common or popular transistor type.
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Old 20th September 2002, 11:07 PM   #7
haldor is offline haldor  United States
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Quote:
Originally posted by KenP
Does that mean that NTE transistors are unreliable or are they just not the same quality as the originals? I'm asking this because I was just about to order some bd139,bd140, bd546 and a few others from Mouser and all they have is NTE.
HI Ken,

My experiance is that what NTE claims is a substitute does not always have the same characteristics as the part in question. I got some NTE fets for a low noise applications (that's all the local part supplier had in stock) and their noise performance was much worse than the real parts.

Used judiciously NTE are ok, just be sure what you are buying is actually a replacement for what you need.

Phil
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Old 20th September 2002, 11:12 PM   #8
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Tom D,

Fairchild have full production of BD140, and maybe other
manufacturers as well. You can find the datasheet at
http://www.fairchildsemi.com/ds/BD/BD140.pdf

There are three versions, BD140-6, BD140-10 and BD140-16,
which are simply classifications of the hFE range of the device.
If your devices are only labelled BD140, it probably means the
manufacturer has not bothered to test the hFE and classify
the devices, so it has a wider spread of hFE values. I suggest
you compare this datasheet to the datasheets for the suggested
NTE devices and try to figure out which one might be the most
appropriate in your case.
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Old 20th September 2002, 11:15 PM   #9
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BD 139 and BD140 are european transistors. Quite common types.
BD546 I do not know. Could it be you mean BC546?

They are/were produced by Philips, Siemens, Telefunken and probably some other manufacters.

How many would you need. I might be able to spare some.

Regards
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Old 20th September 2002, 11:30 PM   #10
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Quote:
Originally posted by Christer
Tom D,

Fairchild have full production of BD140, and maybe other
manufacturers as well. You can find the datasheet at
http://www.fairchildsemi.com/ds/BD/BD140.pdf

There are three versions, BD140-6, BD140-10 and BD140-16,
which are simply classifications of the hFE range of the device.
If your devices are only labelled BD140, it probably means the
manufacturer has not bothered to test the hFE and classify
the devices, so it has a wider spread of hFE values. I suggest
you compare this datasheet to the datasheets for the suggested
NTE devices and try to figure out which one might be the most
appropriate in your case.
Thanks!! I just checked Fairchild also and found the BD140. I found a BD140 at ST Microelectronics also at www.st.com

I'm printing out all the datasheets, as well as the NTE ones, so I should be able to come up with the right one. Thanks again everyone!!
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