Component identification & spec sheet

[KILLSWITCH]

I have been pulling parts from old equipment and running into components with no hits on a search engine.
It seems to me there is no standard (or I don't understand the standard) for part numbers.
Some parts have multiple lines of letters and/or numbers.
Some have no manufacturer markings leaving me guessing where to find the spec sheet. Do some parts simply have no spec sheet available?
Is there some part number standard I should know?

Examples:

[KILLSWITCH]

Example 2:

[KILLSWITCH]

Example 3:

[RomDump]

Some have no manufacturer markings leaving me guessing where to find the spec sheet. Do some parts simply have no spec sheet available?

https://www.mouser.com/ds/2/149/SS8050-117753.pdf

[RomDump]

Example 3:

http://store.alhekma4u.com/content/Diodes/uPC574_u574.pdf

[Jwillis]

Can't see what kind of package the second picture is.

[GerryBags]

Example 1 is a 2N8050, 2 Amps, 800 Volts N-CHANNEL POWER MOSFET http://www.alldatasheet.com/view_datasheet.jsp?Searchword=2N8050

The 2N stands for 2 p-n junctions, you'll notice diodes are 1Nxxxx, and as it's obviously a three terminal device many manufacturers leave off that part and just have the rest of the number. You'll find the same thing with 2SC prefixed transistors, like the 2SC741, which will just have the 741 on it.

[KILLSWITCH]

The 2N stands for 2 p-n junctions, you'll notice diodes are 1Nxxxx, and as it's obviously a three terminal device many manufacturers leave off that part and just have the rest of the number. You'll find the same thing with 2SC prefixed transistors, like the 2SC741, which will just have the 741 on it.

Very useful information, thank you.

*you may have mistakenly linked to the 2n80*

https://www.mouser.com/ds/2/149/SS8050-117753.pdf

This illustrates the point I was trying to get at. How do you know what you have with so little information?
I have several of these and know two things about them.
1. The base is on pin 3
2. The gain is about 30-33 with Ib from <40uA-80uA and began to fall off above 80uA

No spec sheet I could find matches what I know about this transistor.
I also noticed there are A, B, C and D variants. Is that what the C in the lower left corner means? Does the C mean collector?

[Jwillis]

Google is the compendium of electronic knowledge.. Search 8050 transistor and you'll get lots of information to browse.
Generally the suffix letter is a variation of tolerance for the same type of  transistor.  For example the 2n2222 and  2n2222A      very common transistor https://www.electroschematics.com/wp-content/uploads/2009/04/2n2222-datasheet.pdf.

[RomDump]

https://www.mouser.com/ds/2/149/SS8050-117753.pdf

This illustrates the point I was trying to get at. How do you know what you have with so little information?
I have several of these and know two things about them.
1. The base is on pin 3
2. The gain is about 30-33 with Ib from <40uA-80uA and began to fall off above 80uA

No spec sheet I could find matches what I know about this transistor.

I don't know if the datasheet was a match for your device. I used the Package type and the base number you gave me to narrow it down.

Most of my knowledge comes from searching for part information when I was fixing something.  I looked where it was in the circuit and what it did.

I also noticed there are A, B, C and D variants. Is that what the C in the lower left corner means? Does the C mean collector?

Not necessarily. 

Some hints:
Look for manufacture logos.

Transistors  are broken into three Market regions, Americas, Europe, and Japan.  So they usually abbreviate just the base number. 

BTW: I wouldn't use random salvage parts for any of my projects. I would just buy a bunch of jelly bean components and buy special components when required.

For repairs I would just use ECG/NTE cross-reference components, (grab a NTE Cross Reference Book as a reference guide).

As you look at more components you will get the hang of it.