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solder conductivity

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  • Member since
    February 2005
  • From: Southwest US
  • 12,914 posts
Posted by tomikawaTT on Thursday, February 5, 2009 10:45 AM

Rangerover, "Good," is relative.  Lead is less conductive than copper, which is less conductive than silver.  Lead is more conductive than silicon, and infinitely more conductive than bakelite.  For our electrical purposes, lead solder is conductive, period.  (Incidentally, with a background in disaster control, I have learned to be VERY careful around ANYTHING that might explode!)

With sectional track, even in my extreme conditions, I would solder the joiners on 4-6 sections and power them all with a single pair of drops.  I solder jumpers around flex track joints, but one length of flex is equivalent to 4 pieces of sectional track.  Also, I admit that my methods are influenced by a desire to have at least 30 years of trouble-free service from every track circuit.  This is my 'last in this lifetime' layout, and I think I have that much lifetime left...

Chuck (Modeling Central Japan in September, 1964)

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Posted by Rangerover on Wednesday, February 4, 2009 8:43 PM

WOW I didn't know all that about lead solder not being a good "conductor". I worked in maufacturing explosives. If there is any place you want to make sure you are grounded is when you go into a powder magazine and BE GROUNDED OUT. All the powders I worked with are static sensitive, lead azide, lead styphnate,rdx, various lead salts, and the static from your body when you touch it "kaboom" and they won't find you. All the floors in those magazines were pure lead grounded to the outside of the magazine with a cable and we wore conductive sole safety shoes.

I think the lead in our solder works fine, otherwise, I wouldn't be running my trains, DCC, without interruption or dead spots!

I could easilty be soldering feeder wires all this year.  Is that really necessary.  bwchaney

I wouldn't worry about it unless you have or get a dead spot. I soldered most of my joints and always have, some guys use a piece of wire, I never have, heck you got the joiner and that gets soldered too!

However I do leave expansion joints every 6-8'

  • Member since
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  • From: Marblehead, Ohio by the shores of Lake Erie
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Posted by bwchaney on Wednesday, February 4, 2009 8:17 PM

So as I gather so far;  my soldering of joints keeps the track aligned but for better conductivity I should solder feeders directly to the track sections.  Unfortunate I used a lots of sectionall track in my layout.  I could easilty be soldering feeder wires all this year.  Is that really necessary.  bwchaney

  • Member since
    February 2005
  • From: Southwest US
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Posted by tomikawaTT on Wednesday, February 4, 2009 7:51 PM

Solder does not conduct electricity as well as pure copper - true.

BUT!  The cross-section of a #22 feeder wire is miniscule.  Even a minimum solder joint between that #22 wire and a rail (of much greater cross-sectional area) has a cross-sectional area that is gigantic in comparison.  It would take a VERY sensitive ohmmeter to detect the added resistance of the joint - and the 'added resistance' could easily prove to be a negative number.

Conclusion:  For our simple purposes, the resistance of a solder joint can be disregarded.

Chuck (Modeling Central Japan in September, 1964 - with lots of soldered joints between wire and rail)

  • Member since
    July 2006
  • 3,312 posts
Posted by locoi1sa on Wednesday, February 4, 2009 7:49 PM

 BW

 Radio Shack has whats called silver bearing solder. It come as thin as .015. Great electrical conductivity. The only bad thing about soldering the joiners is the loss of movement due to expansion and contraction. It would probably be better to drop another feeder or solder a thin jumper wire across the joiner. When I built my portable modules I soldered either a feeder or jumper wire to every piece of rail. My oldest module is six years old and never had an issue with wireing.

   Pete

 I pray every day I break even, Cause I can really use the money!

 I started with nothing and still have most of it left!

  • Member since
    October 2004
  • From: Colorful Colorado
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Posted by Texas Zepher on Wednesday, February 4, 2009 7:17 PM

bwchaney
Is it true that electrical current dose not move thru a soldered joint.

Solder does carry electricity just not nearly as good as copper or even steel for that matter.  How well it carries it depends upon the exact chemical composition solder 60/40 vs the new stuff whatever it is made of. 

I thought one of the purposes of soldering rail joints was to make sure that track was electrifed by the use of solder.

No, The track is electrified by connecting a good conducting copper wire to the track.  The purpose of the solder is to hold the wire in place.  On a really good solder joint the power is going straight from the copper wire onto the brass or nickel-silver track, all the solder does is hold that connection tight.    If one is passing the current through the lead or other poorly conducting metal the solder is made out of it is like adding a small resistor to the circuit.

Now someone will point out that there is silver solder that conducts better than copper.  True, but I doubt many people are willing to pay the price to use silver solder. 

  • Member since
    September 2008
  • From: Marblehead, Ohio by the shores of Lake Erie
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solder conductivity
Posted by bwchaney on Wednesday, February 4, 2009 6:17 PM

In my all notknowing knowledge of electronics; I guess I really don't know my butt from a hole in the ground.  I thought one of the purposes of soldering rail joints was to make sure that track was electrifed by the use of solder.  I only have feeders on an average of every 12 feet and seem not to lose motion in my dcc layout anywhere.  Any time I do lose a little power or an engine slows down in a certain spot I just solder the rail joint before and after the loss of power.  Is it true that electrical current dose not move thru a soldered joint.  Will I have to put power feeds to this area instead.,  Please help me understand this whole mess.  You folks have helped clear up all the other messes I have gotten into.  Thanks in advance  bw chaney

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