What interesting/funny/engineering-specific Key-chain do you have?

[cat87]

  I know, it's a dumb question, but might turn out to be interesting what the people around here ACTUALLY HAVE ON their key-chain. I'm talking about interesting, nerdy, custom or just funny stuff that you guys use to keep your house keys on.

OK, I'll go first:
I've got two actual, real-life Xilinx Virtex FPGAs, glued back to back. They kinda look nerdy... to me at least. I made this when I used to work for a company, a few years back. They were found to have a few faulty pins and were replaced with other working chips. These were tossed away.

Seemed like a shame really, so I took them and turned them into what could be a potentially expensive keychain. I searched for similar part numbers on digikey a few years ago and and these puppies went for quite some cash.
And yes, they look beat up, but that again, they've been in pockets, bags,  had sweat on them, so it's to be expected they'd loose their shine along the years. 

So, show us what nice stuff you have 

[bd139]

A colleague once had a big RF transistor as a keychain. Until someone informed him it was of beryllium oxide encapsulation. Fortunately he'd only drilled the terminal strip on it.

[Zbig]

Not strictly engineering-specific, but anyway:

[tszaboo]

Mine is Digi-key. Digi-key. Get it? OK, I'll get my coat.

[RoGeorge]

Posting high definition pictures of own keys, wondering what could go wrong.

[joeqsmith]

After reballing this part a couple of times for prototype work, I retired it.  This was a 1513 pin Xilinx V4 LX100.  Cost on these back then was a fair amount.  Maybe $5000 ea. in singles.  Just cut the brass with a ban saw and soldered the BGA to it.  Has not held up over the years..   

[schmitt trigger]

Back in the early 1970s, a local university got rid of its Control Data CDC3300 mainframe computer.

It used a lot of transistorized plug-in boards. They were throwing some spares away, and actually used one on my key chain.

Unfortunately, I lost it many years ago....

[tszaboo]

Posting high definition pictures of own keys, wondering what could go wrong.

That's OK, I have pathetic weak locks. You can break in probably with a screwdriver.

[steve30]

My keyring is a laser cut piece of plastic with my name on it. I made it at school, back in 2005, on our then-quite-new Versa Laser laser cutter. Its lasted well.

The bright colour makes it easy to find. It also glows a nice colour under UV light.

[schmitt trigger]

Also back then in the early 70s, I had one LM3909 led flasher with an AAA battery, all assembled on a key chain.

At the time, it was quite a novelty, and very useful to find keys in the dark.

[TiN]

FB180SA10P MOSFET killed by running outside of SOA in my DIY ATE project for ATX PSU testing rig
It's with me since 2009, so quite beat up mascot already 

[alexanderbrevig]

My key-chain uses one tiny loop in order to bre as tiny as possible. This way it fits in my wallet. Kind of engineering too? :p

[bd139]

FB180SA10P MOSFET killed by running outside of SOA in my DIY ATE project for ATX PSU testing rig
It's with me since 2009, so quite beat up mascot already 

I do believe that's a WASFET 

[SeanB]

I used a old Pentium die as a phone ornament for a while, until the phone died and was not repairable. Current keyring is a length of morris minor accelerator inner cable, and has an embossed leather strip as identifier. I used to keep a genuine Swiss Army knife on there as well, but it eventually wore out, but still have the small multipurpose flat screwdriver from a RS promotional credit card shaped tool set on there, very useful small screwdriver set.

Probably could do the processor keychain, have enough of them around to make an entire keychain from them as well.

[chicken]

For the last 18 years or so, I use a key chain that a friend of mine made from old SIMM modules. It originally still had the RAM chips, but they all fell off after a few years.

I like how the traces start to appear as I wear down the soldermask.

[floobydust]

This is from the 1970's, LM309K that I bought surplus from PolyPaks and it didn't work, lost regulation past 10V in, no label. But gold plate.
So I made it into a keyfob.