Author Topic: Voltage drop  (Read 1506 times)

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kgreen

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Voltage drop
« on: April 08, 2018, 12:10:09 PM »
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Greetings from Newbrunswick Canada.  Is it possible to have a voltage drop in a small door layout.  There is a spot where trains slow.  Track is ballasted in this area so Im thinking its not a track gauge issue.  Layout sat idle for over a year.  Thanks in advance.  Kirk

Dave V

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Re: Voltage drop
« Reply #1 on: April 08, 2018, 12:17:26 PM »
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Greetings from Newbrunswick Canada.  Is it possible to have a voltage drop in a small door layout.  There is a spot where trains slow.  Track is ballasted in this area so Im thinking its not a track gauge issue.  Layout sat idle for over a year.  Thanks in advance.  Kirk

Very much so.  The way around that is to have feeder wires in multiple places.  On my PRR door layout I had 13 pairs of feeder drops and on my little 2.5 x 5 foot Colorado Midland layout I have 15 pairs of drops.  If you're running straight DC versus DCC you can look to see if the headlight dims a little too in that area...if it does, it's a power issue.

But before you do any electrical modification I recommend a thorough cleaning of the railhead, and look in the area that the train is slowing to see if any of the ballast stuck to the inside of the rail.  It's always possible that some ballast is in the wrong place and lifting the flanges of the loco such that you're losing electrical contact between the wheel tread and the railhead.
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peteski

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Re: Voltage drop
« Reply #2 on: April 08, 2018, 02:06:59 PM »
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Sure, it is possible.  In  how many places is the power feed to the track?  Are there blocks or is it all feed from a single throttle?  Are the rail joiners soldered?  Have you thoroughly cleaned the tops of the rail after the layout sat unused?
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kgreen

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Re: Voltage drop
« Reply #3 on: April 08, 2018, 04:39:56 PM »
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track has been ballasted in the area for quite some time.  I have cleaned track and loco wheels super good so I know for sure its not the issue.  Joiners are not soldered and am relying on said joiners for good electrical contact.  Block control with feeders in two blocks so far.  Headlights do not flicker.  Thanks for your interest.  Kirk

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Re: Voltage drop
« Reply #4 on: April 08, 2018, 04:50:51 PM »
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track has been ballasted in the area for quite some time.  I have cleaned track and loco wheels super good so I know for sure its not the issue.  Joiners are not soldered and am relying on said joiners for good electrical contact.  Block control with feeders in two blocks so far.  Headlights do not flicker.  Thanks for your interest.  Kirk

Headlight flicker would indicate momentary power loss (not just a voltage drop). If the drop is not severe then the LED headlight will not even appear to dim.

Relying simply on (not-soldered) rail joiners for good electrical contact is not a best practice.  Those will be the likely suspect contributing to the voltage drop (unless the slowdown occurs on a piece of track which has a wire feeder soldered to it).  You should be able to narrow the affected area to a specific piece of track.

How severe is the slowdown?  Do you have more than one locomotive to try?
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narrowminded

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Re: Voltage drop
« Reply #5 on: April 08, 2018, 05:16:54 PM »
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I'm assuming you've got a real performance problem to be noticeable like that.  If cleaning didn't help start eliminating possibilities.  A quick probe at the rail joints with a metal tool, jumping them, would be an adequate way to quick test the rail joiners.  Jumper wires to the faulty area might help, too.  Or use your multitester and get real numbers.  Once the problem is defined the solution will likely become obvious.  Good luck. 8)
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Re: Voltage drop
« Reply #6 on: April 08, 2018, 06:40:22 PM »
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Greetings from Newbrunswick Canada.  Is it possible to have a voltage drop in a small door layout.  There is a spot where trains slow.  Track is ballasted in this area so Im thinking its not a track gauge issue.  Layout sat idle for over a year.  Thanks in advance.  Kirk
You might want to try applying a drop of contact cleaner, such as DeoxIT, to each rail joiner in the affected area.
http://store.caig.com/s.nl/it.A/id.1703/.f
http://www.partsconnexion.com/product943.html

fire5506

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Re: Voltage drop
« Reply #7 on: April 08, 2018, 09:17:35 PM »
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Rail is actually a pretty poor conductor of electricity. Copper wire is a much better conductor. Make sure you plenty of drops in. Don't go too small on the buss wires under the table either.


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robert3985

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Re: Voltage drop
« Reply #8 on: April 09, 2018, 07:53:08 AM »
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I'm not sure why nobody here mentions it, but BEST PRACTICE in model railroading is to run a feeder from near the center of every...that's EVERY piece of rail...long or short.  NS rail is notorious for being a poor conductor.  Model railroading involves pieces of rail usually a maximum length of 3' if you're using flextrack instead of sectional track and so it's easy to establish 36" as the maximum rail length per feeder.  Also, trusting electrical continuity to little bits of NS sheet metal (rail joiners) between much larger rails is just asking for problems.

Don't ask me how I know this.   :D

Because your slowing is occurring where the track has been ballasted, that's a pretty clear indicator your ballast glue has caused some lessening of the already poor conductive qualities of some (or all) of the unsoldered rail joiners in that area. 

If you plan on ballasting the rest of the layout, then you need to take care of both the present problem and ensure it won't occur on the rest of your layout when you get around to ballasting it.

When I finally decided to go DCC about eight years ago, I also decided to get rid of my voltage-dropping long runs of track and my periodical dead zones from soldered rail joiners cracking caused by the stresses of transporting my modular layout to shows several times a year in various types of weather and rough roads.

This meant soldering 6" long 22AWG copper feeder wires to each piece of rail...hundreds of 'em, and running robust power busses to every power district, in my case 12AWG high-purity, fine-stranded, red/black copper speaker zip wire...which is probably overkill, but I'd rather overkill it than it not be sufficient.

Photo (1) - New outboard red feeders being installed on my Echo LDE:


Note that in the photo, only half of the feeders are shown.  Black inboard feeders and green frog feeders have yet to be installed.

I am going to go out on a limb and say that you have about a 95% chance that your engine slowing is due to not enough feeders and relying on unsoldered rail joiners for electrical continuity.  Dirty rail, debris on the insides of the rails cause stoppages, not slowing. 

As you can see from my photo, a lot of my existing trackage was ballasted when I decided to do the feeders to every piece of rail.  I soldered mine to the underside of the rails after flattening the wire ends and bending them sharply at 90 deg. then trimming them and tinning them. However, they could have been much more easily soldered to the rail web, which is normal practice. I didn't want mine to be seen.

This solved all of my electrical problems and periodically appearing dead zones.  In the eight or nine years since I did this, I have never had any of those problems again, which occurred several times a year before I did it.

Another benefit from this was when I went to DCC, I got rid of the rat's nest of wiring underneath and all the toggle switches I needed to throw just to move trains from one block to another using DC.

Since you have a HCD layout, it isn't going to be difficult for you to tip it up on its side to get at your new feeders underneath your layout if you choose to do this to solve your electrical problems.  I broke my layout down into its 6' sections and tipped them up one at a time, onto a heavy duty folding table to connect the new feeders to newly installed 14 AWG sub-busses using genuine 3M IDC (suitcase) connectors, which in my experience are more reliable than soldered wire joints, not to mention much quicker. My 14 AWG sub-busses were then connected to the 12 AWG main power busses running the length of each 6' layout section.

Photo (2) - In-progress photo of re-wiring one of my eleven layout sections to DCC after ripping out the old DC wiring:


Although I believe what I did was optimal for trouble-free and reliable electrical model railroad wiring, you will probably experience problems feeding your feeders through the holes you drill because of the hollowness of the door your layout is built on, meaning you'll have to fish the feeders through two holes at the same time.  If you don't want to supply a feeder to every rail on your layout, you need to seriously consider the minimal solution of soldering every rail joiner to both rails it's joining.  A better solution would be to solder a 22 AWG solid copper wire across every two pieces of rail which are joined by a rail joiner.  It's also more difficult, but much more reliable than mere soldered rail joiners.

In any case, it appears you definitely need some new feeders from your track to your main power busses...if you have main power busses.  If you don't, it's time to install them.  For your size layout a main power buss consisting of good quality fine multi-strand copper speaker wire would be the easiest to get, and red/black zip cord makes it easier to keep your wiring organized.  I'd suggest 16 AWG wire since you don't have a long run.

Since I was soldering to the underside of already glued-down track much of which was also ballasted, I used my resistance soldering station to do it, and I had to make a special melter-cutter  from a wood burning iron to get rid of the plastic tie-spacer under the rail at my chosen feeder attachment points.  I don't recommend spending nearly 300 bucks for a resistance soldering station just to attach wires to track, but if you already have a resistance soldering station, here are a couple of photos of the melter/cutter I made from an X-acto #11 blade which fits in a Harbor Freight Tools wood burning kit iron.

Photo (3) - Cutter/melter blade for removing between-tie plastic spacers under the rail:


Photo (4) - Cutter/melter in use on RailCraft C55 flextrack already glued down and in use:


Photo (5) - 22AWG rail feeders soldered to the bottom of the rail foot between ties on unpainted Micro Engineering C55 flex:



It looks like you need to do quite a bit of soldering no matter what.  You might have problems in the already-ballasted area because of hardened ballast glue fouling the joints between rail joiners and rails.  A generous alcohol wash and scrub on potential solder spot with a small, stiff brush will get rid of most of the hardened ballast cement (usually either matte-medium or white glue) where you need to solder.  You must use an excellent and self-neutralizing flux to both make your solder joints strong and to prevent any future oxidation due to acid remaining on the joint.  I highly recommend Superior Super Safe #30 gel available at H&N Electronics here: https://www.hnflux.com/   For rail joiners, simple lead/tin electrical solder is inferior since this is a mechanical joint, and I recommend a 96/4 tin/silver solid-core .8mm solder, which is about 7 times stronger than lead/tin solder.  It's available at H&N Electronics too here: https://www.hnflux.com/page25.html

Although the above combination of silver-bearing solder and self-neutralizing flux is much superior to lead solders for mechanical solder joints, when you solder new feeders to your rails, you can use normal multi-core lead/tin electrical solder since this joint isn't mechanical.  However, if you're having problems getting the solder to flow properly at the joint, make sure your iron tip is clean and tinned, that your iron is at least 35 watts and use your Superior #30 Supersafe flux...which will immediately solve your soldering problems...really.

I always pre-tin the tips of my feeder wires too, which greatly speeds things up and encourages a good solder joint between the wire and the rail.  If you're getting too much solder on your joints, try flattening about 1/4" to 1/2" of your solder with flat-nose pliers, which allows it to heat up faster and makes it easier to apply less.

Soldering all of your rail joiners to your rails and adding more feeders will cure your present and potential future electrical continuity problems, with Superior #30 Supersafe flux making the job exponentially easier.

Have fun!

Cheerio!
Bob Gilmore


nickelplate759

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Re: Voltage drop
« Reply #9 on: April 09, 2018, 09:38:25 AM »
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Bob G.,
Your tutorial is great and your cutting tool is nifty.  One thing puzzles me.  How do you tin the underside of the rail without lifting the track?
« Last Edit: April 09, 2018, 01:23:37 PM by nickelplate759 »
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I'm sorry Dave, I'm afraid I can't do that.

trainforfun

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Re: Voltage drop
« Reply #10 on: April 09, 2018, 12:04:05 PM »
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Greetings from Newbrunswick Canada.  Is it possible to have a voltage drop in a small door layout.  There is a spot where trains slow.  Track is ballasted in this area so Im thinking its not a track gauge issue.  Layout sat idle for over a year.  Thanks in advance.  Kirk

Kirk ,
before you rip something try to connect some wires on top using alligator clips .
If you see a difference then add more feeders this is the problem .
Thanks ,
Louis



Point353

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Re: Voltage drop
« Reply #11 on: April 09, 2018, 02:58:49 PM »
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Photo (2) - In-progress photo of re-wiring one of my eleven layout sections to DCC after ripping out the old DC wiring:

Do you use the AC wiring/outlets on your modules during public shows?

peteski

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Re: Voltage drop
« Reply #12 on: April 09, 2018, 03:16:33 PM »
+1
I'm not sure why nobody here mentions it, but BEST PRACTICE in model railroading is to run a feeder from near the center of every...that's EVERY piece of rail...long or short.  NS rail is notorious for being a poor conductor. 

Why Bob?  Because you are our resident track and track wiring expert and we were all just waiting for you to chime in.  :)  You explain things so much better than the rest of us. You are also very serious about it (after all, the reason for your recent hiatus was a write-up about track). And no, I'm not being cheeky.

I suspect that the other reason was because the person who posted the question didn't ask - they just wanted some troubleshooting advice for their problem. But at this point they have the whole kit and caboodle -  now they can lay the track with the best of them.
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kgreen

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Re: Voltage drop
« Reply #13 on: April 09, 2018, 07:34:09 PM »
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Wow  Thanks for your replies.  Most informative indeed.  I will add more feeders as time allows.  I know that relying on joiners is not ideal but I guess up until now, ten years or more its never been a problem
Kirk

robert3985

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Re: Voltage drop
« Reply #14 on: April 16, 2018, 08:34:24 AM »
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Bob G.,
Your tutorial is great and your cutting tool is nifty.  One thing puzzles me.  How do you tin the underside of the rail without lifting the track?

I don't tin the underside of the rails...just the flattened and bent feeder tips.  With my resistance soldering tweezers, I can feel the solder melt and also see it melt (using my trusty OptiVisors).  The Superior #30 Supersafe gel flux makes the joint good every time, and with the resistance tweezers, I can hold the joint in place after I step off the power switch to hold the feeder in place while the solder solidifies.  I apply almost a "blob" of solder when I tin the feeders tips, so I rarely have to add much extra solder when soldering them to the undersides of the rails.

If I didn't have my resistance soldering station, I'd bend the flattened tips of the feeders just enough for the bent tip to lay on the top surface of the rail foot between the edge of the foot and the rail web.  I think that would be pretty unobtrusive and easy to do with an iron and a dental pick to hold it in place while the solder cools.

Cheerio!
Bob Gilmore
« Last Edit: April 16, 2018, 09:44:37 AM by robert3985 »