# Model：D2118



## amon13 (Feb 20, 2011)

help me with this -Model：D2118
Category：Transistor - ROHM

what is in there ............
how to deal with this


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## dtectr (Feb 20, 2011)

go to www.alldatasheet.com input ALL the letters/numbers on the chip & follow the breadcrumbs from there.

BTW - bookmark that site - you'll use it a lot.


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## macfixer01 (Feb 22, 2011)

dtectr said:


> go to http://www.alldatasheet.com input ALL the letters/numbers on the chip & follow the breadcrumbs from there.
> 
> BTW - bookmark that site - you'll use it a lot.




Amon13,
It's been my experience that that type of transistor number (beginning with a letter) is a Japanese part number and is often truncated when it's printed on the part. More than likely the full part number is 2SD2118. Similarly other Japanese transistors may begin with 2SBxxxx or 2SCxxxx but would be printed on the part itself as Bxxxx or Cxxxx.

USA transistor part numbers generally always begin with 2N (which I always assumed was because of the two P/N junctions) and diode part numbers generally begin with 1N (which I again assume is because they have a single P/N junction). My assumptions are just that though. For example though some commonly used components are 2N3904 transistors and 1N3148 Diodes. Of course generic replacement product lines like NTE have their own numbering scheme for marketing purposes. Then they publish cross-references to match their generic parts up to the original manufacturer part numbers that they'll replace.

macfixer01


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## amon13 (Feb 22, 2011)

macfixer01 said:


> dtectr said:
> 
> 
> > go to http://www.alldatasheet.com input ALL the letters/numbers on the chip & follow the breadcrumbs from there.
> ...



macfixer01 
thank you very much for this information 
realy full part number is 2SD2118
2SD2118 TRANSISTOR (NPN)
FEATURES
Power dissipation
PCM: 1 W (Tamb=25℃)
Collector current
ICM: 5 A
Collector-base voltage
V(BR)CBO: 50 V
Operating and storage junction temperature range
TJ, Tstg: -55℃ to +150℃
but i wonder is it some Precious Metals
in those transistors 
:roll:


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## patnor1011 (Feb 22, 2011)

Answer is easy. You have them at hand so why not to test them? When you will do that let us know. Use stannous and DMG, that will answer your question.
There are many manufacturers and types to give you answer based on picture. They contain mainly copper but you will never know until you test them. If you do not have means for testing some member might do that for you if you send him sample. I would be looking for possible gold, silver maybe Pd but that is just a guess.


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## amon13 (Feb 25, 2011)

patnor1011 said:


> Answer is easy. You have them at hand so why not to test them? When you will do that let us know. Use stannous and DMG, that will answer your question.
> There are many manufacturers and types to give you answer based on picture. They contain mainly copper but you will never know until you test them. If you do not have means for testing some member might do that for you if you send him sample. I would be looking for possible gold, silver maybe Pd but that is just a guess.




ok im newby i know that i can test wih stannous an DMG but i dont know from where to buy DMG


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## johnny309 (Feb 25, 2011)

If you have one single piece of that....don't bother.
On the other hand...if you have more than 20 pcs.(working )...you can sell those ....the only value in this is cooper....and that piece is soo small.
Take your time and study this forum,search for information....You would find (on this forum......free information by the way....to assay electronic componets).....

P.S.
An old song (UB40...the name of the band) says:

Wise men say - Only fools rush in!


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## macfixer01 (Mar 1, 2011)

Amon13,
Most often I've found that if transistors contain any gold internally you'll see evidence externally. The small metal can type transistors have a tiny tab on one side at the bottom edge, if the tab is gold plated the inside will be also. If the leads or the package bottom surface (between the leads) are gold plated the inside likely will be also. Note that inside only the bottom surface would be plated, the metal cap is normally just copper or steel colored inside. Plastic packaged power transistors like yours won't have gold inside unless you see it externally on the leads or collector/heatsink tab. Large power transistors in the TO3 packages again will have gold plated leads or gold on the bottom and/or top of the metal package if there is gold inside. The small molded plastic transistors (with no external collector tab) are hit or miss. Even if they don't have gold plated leads they may have gold plated structures inside. It's best to just crack one of each type open and check. Then you will know whether or not to save like-numbered parts from the same board.

Here are some samples. Sorry for the fuzzy photo but I got a new camera for Christmas and have yet to find time to read the manual about taking close ups. Strictly speaking the packages with more than 3 leads are actually integrated circuits but can be found in transistor type packaging sometimes. You can see some of the tin can type transistors at the lower left, some intact and some with the can torn off and only the bottom disc saved. The two discs with grey bottoms showing have gold plating on the other (interior) side but they also had the tiny gold plated tab showing outside as an indicator. There are a few molded plastic transistors at the bottom right that have already been split in half, but haven't had the internal gold plated leads peeled off the plastic yet. At the right is a small pile of some of the gold plated leads. There is also a plastic packaged power transistor near the bottom center and a couple of the gold plated collector/heatsink pieces removed from that type of transistor.

So you can see there is gold content in many transistors but whether it's worth it to extract depends how much time you waste on it. It's just a hobby to me. But if you were just incinerating a bunch of plastic transistors or putting a batch of metal packaged transistors in a crock pot with HCl to break them down, then what have you got to lose? 

macfixer01


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## parrothead (Mar 3, 2011)

Off topic for a second. In taking good close ups with a digital camera, have the camera back a few feet from what you are trying to capture. Zoom in as far as possible. Load the picture to your computer and crop to the item you want to look at. Basically, you can not get a good close up when you are close up to the item.

I can stand with the camera 3 feet away or so, zoom in, let focus and crop the picture down to be able to read the karat markings inside a ring.

/back on topic. Hope this helps.


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## Barren Realms 007 (Mar 3, 2011)

parrothead said:


> Off topic for a second. In taking good close ups with a digital camera, have the camera back a few feet from what you are trying to capture. Zoom in as far as possible. Load the picture to your computer and crop to the item you want to look at. Basically, you can not get a good close up when you are close up to the item.
> 
> I can stand with the camera 3 feet away or so, zoom in, let focus and crop the picture down to be able to read the karat markings inside a ring.
> 
> /back on topic. Hope this helps.



This one was taken at about 4"-6" distance from the camera.


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## parrothead (Mar 4, 2011)

Barren Realms 007 said:


> parrothead said:
> 
> 
> > Off topic for a second. In taking good close ups with a digital camera, have the camera back a few feet from what you are trying to capture. Zoom in as far as possible. Load the picture to your computer and crop to the item you want to look at. Basically, you can not get a good close up when you are close up to the item.
> ...


Wow. Nice close up. My camera can not do that. Very very nice.


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## jimdoc (Mar 4, 2011)

See if your cameras have a macro switch.

Jim


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