What are 0 ohm resistors for?

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Ok, so I know I am new at the hardware side of things but this one makes NO sense to me.

A buddy of mine at work insisted that they make 0 ohm resistors. I said "Of course they do. It is called wire and in comes in many sizes and colors." Then he pulls out the digikey catalog and shows me! He didn't know why and I can see why someone would spend almost a dollar on a 50mm length of wire when you can buy a 30m spool of 22 gauge for $15.

http://dkc3.digikey.com/PDF/T073/P1678.pdf

There has to be a reason someone would go the the expense of manufacturing these things. What am I missing?

I don't mind loosing beer bets (as I did on this) but there is NO WAY an entire industry is conspiring against me.

You can have my mac when you pry my cold dead fingers off of it.

Kevin McEnhill -- mcenhillk@gmail.com

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Since 0 Ohm resistors look the same as its resistive brothers, it can be treated the same way in f.i. automatic insertion machines for PCB-manufacturing.

In SMT they are commonly used to let tracks on one side of the PCB cross: the second track goes between the 2 pads of the smd-resistor of 0 Ohm

Third reason is to use them as configuration resistors. (Have a look at the schematic of the Butterfly: you'll find several of these 0 Ohm resistors)

So yes, you'll have to buy him a beer. Cheers !

Nard

Dragon broken ? Or problems with the Parallel Port Programmer ? Scroll down on my projects-page http://www.aplomb.nl/TechStuff/TechStuff.html for tips

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This reminds me on a tube I once saw in a tube-museum.
They had lots of diodes,triodes, tetrodes,pentodes and
so on, but the exhibition also showed a Nullode, a
tube with NULL (=zero) electrodes. I think I was
disturbed the same way you have been about 0-Ohm
resistors.

But there is an explanation. As often, Google knows
the answer also !

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Well, consider that you have a PCB with options. Say you remove or add options. The "Zero Ohm " may be used to enable an input that would otherwise be inhibited, with out the "Zero Ohm " resistor to pull that input to VCC or GND.

In my serial backpack, I use "Zero Ohm " resistors s jumpers to set the BAUD rate to 115.2K BAUD as the default when it is shipped. If the end user wants one of the other three available BAUD rate, one or both of the "Zero Ohm " jumpers are removed. The internal pull up resistors take care of the reset.

It so happens that I primarily make single sided PCBs for most of my projects. "Zero Ohm " resistors are great for use as jumpers, eliminating the need to drill holes and insert "Thru-Hole " jumpers.

Handy devices, they are - "Zero Ohm " resistors...

Also, several months ago, there was a thread where, the exact same question about "Zero Ohm " resistors was asked. You might do a forum search or Google search and see what turns up.

Carl W. Livingston, KC5OTL
microcarl@roadrunner.com

"There are only two ways to sleep well at night... be ignorant or be prepared."

The original Dragon Slayer !

Long live the AVR!!!

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microcarl wrote:
In my serial backpack, I use "Zero Ohm " resistors s jumpers to set the BAUD rate to 115.2K BAUD as the default when it is shipped. If the end user wants one of the other three available BAUD rate, one or both of the "Zero Ohm " jumpers are removed. The internal pull up resistors take care of the reset.
That works very well in your serial backpack. I've been greatly enjoying the serial backpacks I got from you and am preparing to soon post a review of your fine project.

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We use lots of 0 Ohm resistors in our prototype cel phone designs at work. Since things are in the early prototype phase, there's often several possible configurations. Since it's very expensive to set up and run a PCB build, 0 Ohms are often placed around to allow for multiple configurations. Connect something one way and if you want to test the other way, populate a few and remove a few and you have the other configuration.

Don't worry, though, caught me by surprise a bit when I first saw them, too =)

Clancy
_________________
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Yeah, it seems to me that they would just be used in cases where it's impracticable or undesirable to solder a jumper wire when you can cross a PCB route with an SMD device (that can be used by an auto-pickup and batch soldered.)

If there's 0-ohm thru-hole versions though, that would not make much sense to me...

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Quote:
If there's 0-ohm thru-hole versions though, that would not make much sense to me...
See my first post in this thread :)

Dragon broken ? Or problems with the Parallel Port Programmer ? Scroll down on my projects-page http://www.aplomb.nl/TechStuff/TechStuff.html for tips

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Yep. :)
And clpalmer beat me to the other thing I was going to say too, so yeah, I got to this thread way too late.

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Psychlow wrote:
If there's 0-ohm thru-hole versions though, that would not make much sense to me...

Then you haven't done much PCB layout using thru-hole components. If making single sided PCBs, thru-hole "Zero Onm " resistors are essential - especially when the PCB is stuffed via "Auto Insertion " equipment.

Carl W. Livingston, KC5OTL
microcarl@roadrunner.com

"There are only two ways to sleep well at night... be ignorant or be prepared."

The original Dragon Slayer !

Long live the AVR!!!

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Incidentally, zero-ohm resistors are anything but. I remembera buddy of mine used one in a pinch to create a low current ammeter. I must say it worked rather well too.

Jim

I would rather attempt something great and fail, than to attempt nothing and succeed. - Fortune cookie

 

Don't hang your hat on expectations because this often leads to disappointment.

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