Testing keys without connecting to a computer

[reidpr]

Suppose I'm tinkering with a keyboard. How can I test keyswitches (installed or not) without soldering them in and connecting the unit to a computer? In particular, I'd like to distinguish between working 100% of the time and 99% of the time. (I currently have some keys that intermittently give duplicate key events.) Is this a job for an oscilloscope?

Thanks,

Reid

[Dox]

It's a job for a multimeter.


edit: This should get you started.

[The Solutor]

It's a job for a multimeter.

 

Not exactly a job for a multimeter

Well, if you are talking about whether a switch is chattering it would be a LOT easier to solder it in. Spam the key 100 times. And then count if you got 100 characters out.

He can use an old mouse with one of the original switches removed, an two crocodile* clips to quickly test the switch.

(*)I hope they are called crocodiles also in the US.

[alaricljs]

(*)I hope they are called crocodiles also in the US.

Oddly enough we call them alligator clips...

[The Solutor]

Oddly enough we call them alligator clips...

Hahah

I presume that every continent chose the nearest reticle...

[The Solutor]

That was the my forbidden dream for almost a decade, then I got one a "cheap" 20Mhz dual trace one.

It is still alive, but is in the hands of my ex coworker, which later bought some more expensive models (something like 6/7K$)

[dr/owned]

Yep you'd need an oscilloscope.  The analog ones you can find for cheap nowadays are just junk but would probably work fine for you.  You just need visual inspection more than actual accuracy of measurement.  If you happen to be an EE now would be a good excuse for buying a $3000 Tektronix digital

Edit: I also get the feeling you could do something clever with an LED and semi-high speed camera at 60 fps.  Won't show you microsecond voltage hysteresis but would give you a general idea.

[Keylamity]

Not exactly a job for a multimeter

He can use an old mouse with one of the original switches removed, an two crocodile* clips to quickly test the switch.

(*)I hope they are called crocodiles also in the US.

Actually the American term for them is "roach clips".

[The Solutor]

Wikipedia seem differentiate between crocodile and alligator clips

http://en.wikipedia.org/wiki/Crocodile_clip

that's the american stoner term.

Yes wikipedia says also you are right...

http://en.wikipedia.org/wiki/Roach_clip

[Keylamity]

that's the american stoner term.

Used to be, but it's worked it's way into regular parlance...see for example American ebayers selling electrical-use crocodile clips:

here

and   :smokin:

here.

We used to occasionally call them roach clips in our electronics class but our (Canadian) instructor would, ahem, correct us.

[dr/owned]

Proper term I've ever heard used as an EE is alligator clip.  Mouser seems to follow the Wiki standard where croc denotes large car jumper stuff.

[The Solutor]

Hahaha

In Spanish is caiman clips

http://www.proz.com/kudoz/spanish_to_english/chemistry%3B_chem_sci_eng/892860-pinzas_caiman.html

[What is X?]

in australia we have crocodiles but still call them alligator clips :/

[Soarer]

Is this a job for an oscilloscope?

Yes. Either the switch bounces for too long (most likely), or contact is not maintained consistently while it is depressed. Cherry switches are specified to have less than 5mS bounce time, and typically it only lasts a couple of mS.

Wikipedia seem differentiate between crocodile and alligator clips

http://en.wikipedia.org/wiki/Crocodile_clip

That page needs more pedantry! 'Standard clip' indeed.

[The Solutor]

That page needs more pedantry!

 
Italian wikipedia seem a good example.

It provides three variations in Italian and two in English.:happy:

http://it.wikipedia.org/wiki/Connettore_a_coccodrillo