Is there anything available to see if a particular transistor can be replaced with a different one .
There are books galore on this but surely someone knows of a site that has them listed and searchable
My query is a simple one
I have no 2N5551 transistors on hand and I want to see if one in my box will do the job.
You can compare data sheets.
You can get one of the universal replacement part catalogs and see if your two candidates cross to the same universal replacement.
2N5551 is a NPN 160 volt 600mA part. With out knowing what and ware your are using it, you should choose a similar part.
NPN: Must be!
160 volt: Maybe a 100 volt part will work. I don't know.
600mA: There are many parts in the 500mA to 1A range.
The physical size is TO-92. (little black "D" shaped) Might be important.
2N5550, KSC2316, KSC2383 (I found these three)
It is a high voltage part so it will be hard to find a replacement.