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Resistors, need clarity.

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  • Member since
    February 2002
  • From: Reading, PA
  • 30,002 posts
Posted by rrinker on Tuesday, October 6, 2015 7:38 AM

xdford

Dave Wrote -The end of the resistor that has stripes closest to the end is the positive end and the more blank end is negative.   Sure hope I am right.  Am I ???

Not quite Dave but you are right in one respect, that the end that the color code value starts from is nearer to the end.  Given the "panic" engendered by electronic boffins to those of us less experienced about polarity it is understandable you would have concerns. In short  resistors, globes and non electrolytic capacitors are the only devices I know of commonly used by model railroaders that are not polar.

What is a good idea is if the resistor is protecting an LED, place the resistor to the positive end of the LED rather than after it. The voltage drop is the same across the LED but the protection is arguably better,

Hope this helps and lets keep some of the "silly" questions going and we will ALL learn something!!!

 

Regards from Australia

Trevor   www.xdford.digitalzones.com  for your interest and you might like the Hints and Tips and the basic electronic stuff

 

 Relays and switches are also not polarity sensitive.

It does not matter which side of the LED the dropping resistor goes on, electrically it is the same (those various pesky 'laws' like Kirchoff's and Ohm's). It DOES make good sense to be consistent whichever way you do it, not from a sense of one way being better than the other, but from being able to come back later and recognize what you did. Same with any wiring, really. Keeps it easier to understand. It's quite tempting, when you are 5 feet short of red wire on a Sunday evening, to splice in a spare piece of blue wire just to finish the project, but next year when you have a problem in that section and try to troubleshoot it, you will be confused to no end when the red wire you are tracing suddenly turns blue. Be consistent and document your work, and things will be much easier to maintain going forward.

                 --Randy


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

  • Member since
    December 2001
  • From: AU
  • 713 posts
Posted by xdford on Tuesday, October 6, 2015 5:49 AM

Thanks Dave... I had just got off the phone to a Dave (Delaney) over here so I was still in "Dave" mode... and good luck with it John!

Trevor

  • Member since
    July 2006
  • From: Bradford, Ontario
  • 15,797 posts
Posted by hon30critter on Tuesday, October 6, 2015 12:23 AM

Hi Trevor:

I believe your quote should be attributed to the OP, not me.

Dave

I'm just a dude with a bad back having a lot of fun with model trains, and finally building a layout!

  • Member since
    December 2001
  • From: AU
  • 713 posts
Posted by xdford on Monday, October 5, 2015 11:00 PM

Dave Wrote -The end of the resistor that has stripes closest to the end is the positive end and the more blank end is negative.   Sure hope I am right.  Am I ???

Not quite Dave but you are right in one respect, that the end that the color code value starts from is nearer to the end.  Given the "panic" engendered by electronic boffins to those of us less experienced about polarity it is understandable you would have concerns. In short  resistors, globes and non electrolytic capacitors are the only devices I know of commonly used by model railroaders that are not polar.

What is a good idea is if the resistor is protecting an LED, place the resistor to the positive end of the LED rather than after it. The voltage drop is the same across the LED but the protection is arguably better,

Hope this helps and lets keep some of the "silly" questions going and we will ALL learn something!!!

 

Regards from Australia

Trevor   www.xdford.digitalzones.com  for your interest and you might like the Hints and Tips and the basic electronic stuff

  • Member since
    August 2006
  • From: Saskatchewan
  • 2,201 posts
Posted by last mountain & eastern hogger on Monday, October 5, 2015 10:53 PM

Whistling

Thanks Dave, George and Trevor thats what I wanted to know.

For the record I did google it, but for that exact question I did not find an answer.  Maybe Rich did.

Johnboy out,............

from Saskatchewan, in the Great White North.. 

We have met the enemy,  and he is us............ (Pogo)

  • Member since
    July 2006
  • From: Chamberlain, ME
  • 5,084 posts
Posted by G Paine on Monday, October 5, 2015 10:47 PM

The stripes are there to indicate the resistor ohms and wattage. A Google search can find charts that give this information, or just measure the ohms with a meter

George In Midcoast Maine, 'bout halfway up the Rockland branch 

  • Member since
    July 2006
  • From: Bradford, Ontario
  • 15,797 posts
Posted by hon30critter on Monday, October 5, 2015 10:27 PM

Johnboy:

Resistors do not have polarity. It doesn't matter which way they are installed.

By the way, thanks for asking the question here. This is precisely what the forums are for, and personally I choose to encourage people to post here rather than suggesting that their question is somehow inappropriate.

All the best.

Dave

I'm just a dude with a bad back having a lot of fun with model trains, and finally building a layout!

  • Member since
    October 2006
  • From: Western, MA
  • 8,571 posts
Posted by richg1998 on Monday, October 5, 2015 10:10 PM

last mountain & eastern hogger

Whistling

Could one of you electronic whizzes clarify for me if I am correct.

The end of the resistor that has stripes closest to the end is the positive end and the more blank end is negative.   Sure hope I am right.  Am I ???

Thanks in advance,

Johnboy..........

 

Hope this is not a joke. Resistors have no polarity issues. A simple Google search would have indicated that.

Rich

If you ever fall over in public, pick yourself up and say “sorry it’s been a while since I inhabited a body.” And just walk away.

  • Member since
    August 2006
  • From: Saskatchewan
  • 2,201 posts
Resistors, need clarity.
Posted by last mountain & eastern hogger on Monday, October 5, 2015 9:53 PM

Whistling

Could one of you electronic whizzes clarify for me if I am correct.

The end of the resistor that has stripes closest to the end is the positive end and the more blank end is negative.   Sure hope I am right.  Am I ???

Thanks in advance,

Johnboy..........

from Saskatchewan, in the Great White North.. 

We have met the enemy,  and he is us............ (Pogo)

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