Newbie question: Identifying Transistors

[James Howe]

I recently purchased a 'grab bag' of components which included a bunch
of transistors. Most of the transistors are what I think of as a
typical transistor, black case, flat on one side. Many of these
transistors have no markings on them at all. Others say things like
"NTCMP S3706" or "NTC P N4916". Is there a reasonable way to learn
more information about the specifications for these transistors?

Thanks.

James Howe
http://public.xdi.org/=James.Howe

 

[Gareth]

I recently purchased a 'grab bag' of components which included a bunch
of transistors. Most of the transistors are what I think of as a
typical transistor, black case, flat on one side. Many of these
transistors have no markings on them at all. Others say things like
"NTCMP S3706" or "NTC P N4916".

The first thing I would try is typing the numbers on the marked devices
into Google. If that doesn't work try truncating the part number as the
last few characters could just be a batch code, date code of package
options. If you recognise the manufacturer you could go to their
website and see if you can find the part there.

Here are the websites of some transistor manufacturers:

http://www.onsemi.com

http://www.fairchildsemi.com/

http://www.zetex.com/

http://www.infineon.com


For the unmarked devices it could be very difficult. There are many
electronic devices which have three legs so these parts may not even be
transistors.

Good luck.

Gareth.

--

 

[BobGardner]

Many of these

transistors have no markings on them at all. Others say things like
"NTCMP S3706" or "NTC P N4916".

=============================
You can tell if its pnp or npn with an ohmmeter.... if you know the pinout....
red on base, black on emitter showing some lo ohms... its npn

For the ones with numbers, type em into google... mps3706 sounds like a
motorola (or On semiconductor) number, 2N4916 might be a vaild number...

 

[Rich Webb]

I recently purchased a 'grab bag' of components which included a bunch
of transistors. Most of the transistors are what I think of as a
typical transistor, black case, flat on one side. Many of these
transistors have no markings on them at all. Others say things like
"NTCMP S3706" or "NTC P N4916". Is there a reasonable way to learn
more information about the specifications for these transistors?

Radio Shack has a handly little (and inexpensive) tester that will
classify common small signal transisters by type (NPN, PNP) and flag the
base and collector leads. Part # 22-330. Not sure that this is in their
current catalog but you might be able to find a store with one.

Also, many general-purpose multimeters have a socket that accepts a
transistor and that then reads out hfe (more or less). It helps to know
the type and CBE order, though, so even with one of these the little RS
gadget is helpful.

 

[Squidster]

"NTCMP S3706" or "NTC P N4916". Is there a reasonable way to learn

NTC is a Taiwanese semiconductor manufacturer; Nanya Technology
(http://www.nanya.com), and probably OEMs for Motorola/ONSemi for the
MPS3706, which is Motorola's original implementation of the generic
2N3706. Datasheet is here:
http://www.datasheetarchive.com/search.php?search=mps3706&mfg=ALL

PN4916 is originally from Fairchild, in your case is probably OEM-sourced
implementation from NTC too.
Datasheet is here:
http://www.datasheetarchive.com/search.php?search=pn4916&mfg=ALL

It all boils down to exposure and experience. Just like everybody knows
what brands of PC exist in the market. You'll soon learn what are the
dominant seminconductor manufacturers are there...

 

[Active8]

I recently purchased a 'grab bag' of components which included a bunch
of transistors. Most of the transistors are what I think of as a
typical transistor, black case, flat on one side. Many of these
transistors have no markings on them at all. Others say things like
"NTCMP S3706" or "NTC P N4916".

In a male or female voice? That's a big clue.

Is there a reasonable way to learn
more information about the specifications for these transistors?

Besides those other good suggestions, electronics parts stores (real
ones) have cross-reference guides. They gave me one (the NTE book) a
long time ago. Note, the specs of the original and replacement might
not be an exact match, but hey, it's a grab bag

Maybe Bainsville Electronics in b'more (or someone like that) has a
cross-ref search on their web-site.