11/45 is alive (I'm singing "who's johnny")

Tony Duell ard at p850ug1.demon.co.uk
Wed Jul 13 17:52:51 CDT 2005


> I used to joke about why there's no tolerance band on 'zero ohm jumpers'
> (short-circuit shunts built with the same package outline as a resistor,

There a plenty of jokles about 20% 0-ohm jumoers being cheaper than 10% 
ones :-).

I believe the actual spec for a zero ohm jumper does give a maximum 
resistance if it's installed with a particular lead length. Which makes 
sense.

> often used in instances where a board-stuffing machine needs to put
> *something* in a hole where a resistor might have gone.  Usually they
> have one black band in place of the regular 'resistance value' bands).  

Zero ohm jumpers are a relatively modern idea. I've seen boards in 
classic computers (some old HP stuff, for example) where options were 
selected by soldered-in low-value resistors (10 ohm, 22 ohm, etc). A 
shorting link would have been fine, I guess they used the resistors for 
the same reason that zero-ohm jumpers are now used -- automatic 
board-stuffing machines can insert them. Zero ohm jumpers didn't exist 
back then.

-tony



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