Another Possible Cause for Sound Dropouts: Too Few Track Feeders?

[tehachapifan]

I don't recall this being discussed before regarding sound dropouts, so forgive me if it has or if this is incredibly obvious. Anyway, I've noticed a bit of a pattern regarding sound dropouts with some of my sound-decoder-equipped locos that I can't come up with another explanation for. My layout is a bowl-of-spaghetti-type table layout with what is essentially a continuous, but very long, double-track loop (about a 7 minute run at realistic speeds, IIRC). Although it's been years, I've never improved the track wiring beyond the temporary hookup stage...meaning VERY few track feeders and LONG stretches of track between feeders . While it never created much of a problem when it was all still just DC, I've noticed that some of my DCC sound equipped locos will experience sound dropouts in certain locations, apparently regardless of track or wheel cleanliness. If I try to lash-up 3 sound-equipped locos, these sound dropouts will be severe in these spots but not near as bad with just 2 locos. I've also noticed that one particular loco, acting as a trailing unit, will have severe dropouts when lashed to a certain lead loco but almost none when lashed to a different lead loco...as if the former lead loco draws more power than the latter. My theory is that the power at some of these remote areas of track drops to a point below what these sound decoders require for uninterrupted operation, sometimes even causing a complete shutdown and restart but mostly causing a brief studder or two with a headlight flicker. While I'm sure the track on many layouts is probably far better than mine, perhaps this is still a possible cause of the occasional sound dropout. Thoughts?

...yes, I do plan on adding WAY more feeders.

[peteski]

I think that it is unlikely. As I see it, if there was enough of a voltage drop (due to the resistance in the track/feeders combined with the current draw of the consist), it should visibly affect all the locos in the consist.   Headlight flickers to me seem to be pretty good indication of power interruptions (not just "brownouts").

Or if what you say is true, then you have some really severe resistance  in your track/feeders.

What if you run the suspect (sound) loco through the same area alone?  What if you run a single non-sound loco through that area alone?
I would say, as general rule, a sound equipped N scale loco draws about a double the current of a non-sound loco.

[jagged ben]

I think that it is unlikely. As I see it, if there was enough of a voltage drop (due to the resistance in the track/feeders combined with the current draw of the consist), it should visibly affect all the locos in the consist.   

There could be varying voltage drop within each locomotive depending on the quality of internal electrical connections as well as the load.  The motor current draw in particular could vary.  I guess the sound current draw could also vary depending on decoder design and volume levels.

Headlight flickers to me seem to be pretty good indication of power interruptions (not just "brownouts").

But that could be at the decoder level, not the track level.  If the decoder ceases operating because voltage drops too low, then a brownout looks like a power interruption.  I'm not sure if decoders behave that way, but I don't know that they don't, either.   Particularly sound decoders.

To summarize, while I'm not sure Russ's theory is correct, I don't think I would call it unlikely either.  One way to find out more... add more track feeders!   

[peteski]

To summarize, while I'm not sure Russ's theory is correct, I don't think I would call it unlikely either.  One way to find out more... add more track feeders!   

It would be interesting to try to monitor the voltage at the affected areas (even with just a standard multimeter set for AC voltage measurement, and compare that voltage to a voltage readings taken at the unaffected areas (while the train is passing through of course, so the reading is taken under an electric load).

[tehachapifan]

Thanks for the feedback, guys!

I don't, yet, own a multi-meter but intend to get one. I would also be interested in what the readings would be at these remote/distant areas of track. While I mentioned never having problem with this when the layout was only DC, there always was some definite speeding up of the trains when near a track feeder and significant slowing when far away. I actually sort of made this work in my favor when running straight DC and with the right-hand running setup of my layout, as I could sort of create automatic speed-ups and slow-downs depending on where I placed feeders. This was kind of nice as I could just let the trains run on their own without having to do anything, say, when the train began heading down a rather steep grade, into a helix where I currently have no (downgrade) feeders. With feeders in there, the train would absolutely fly down the grade (especially my Katos and my older Atlas locos with the "fast" motor). This is probably not a recommended way of achieving this but it sort of worked pretty cool at the time. Anyway, I think this showed that there was a relatively significant voltage drop in these remote/distant areas. If this can cause the sound decoder behavior I described currently remains unknown, until I can do more tests or add feeders as mentioned.

[peteski]

Thanks for the feedback, guys!

I don't, yet, own a multi-meter but intend to get one.

A multimeter should be one of those indispensable tools that a model railroader (especially one who owns a layout) should have.  You can find small digital multimeters for as low as $5!  And those are good enough for 99% of tasks related to model RR.  That is about a cost of a Duracell 9V battery ( which is another indispensable test tool in my tool arsenal)!  A multimeter for a fraction of what a boxcar costs.  No brainer.

Since we are on the subject, a 6" digital caliper is another one of those indispensable tools.  Especially when doing any modeling more advanced than out-of-the-box kit assembly. Hey, it comes in handy even with those simple kits.  And now you can sometimes find them for as low as $10, or more readily at around $20. I owned one of those calipers (I have 3 now) for over 20 years and I would be lost without it.  There are so many used for it!  I've heard grumblings that those calipers are no accurate. I had no such problems. The are probably uding the same elctronics used on the $200 versions.

Where to find both items?  Try eBay, Amazon, of Freight Harbor stores.   I got my calipers from Harbor Freight, and my $5 multimeter from Electronic Goldmine (online surplus store) when they were on sale.  I've been involved with electronics (both professionally and as a hobby) since my teenage years, so to put this in perspective, I own several multimeters (including old-fashion analog one), capacitance meter, DCC packet analyzer, and couple of oscilloscopes. But I still use that $5 multimeter most often (since I most often do basic checks). 

[MK]

Find a coupon on Harbor Freight for the $10 digital caliper.  Then find a coupon for a free multimeter with any purchase.  Basically $10 would get you both.  And I agree with Peteski, both are indispensable in our hobby.

[Lemosteam]

I would add only a third thing.

In my case I also had to learn how to use the multimeter, right @peteski ??      Still learning that darn thing.

So far my most useful choice on that meter is continuity, LOL.

[peteski]

I would add only a third thing.

In my case I also had to learn how to use the multimeter, right @peteski ??      Still learning that darn thing.

So far my most useful choice on that meter is continuity, LOL.

LOL, but if you don't own one, learning is even harder.  Still learning?  We never really stop learning (at least that is how I feel).

[lashedup]

We were talking to the Digitrax guys about our modular layout and when you need to consider more boosters. Their first recommendation was to use larger gauge wire on feeders (we were using 24g on feeder drops) and they recommended going as big as we could get away with in n scale.  I suspect that *if* you have some spots with voltage drops it should be easy to correct with a few more feeders. My new ESU system actually shows overall voltage use which is nice. 

[tehachapifan]

LOL, but if you don't own one, learning is even harder.  Still learning?  We never really stop learning (at least that is how I feel).

This is actually what has kept me from pulling the trigger on getting one. I look at all the markings, settings, etc., on them and have absolutely no idea what any of it means.

We were talking to the Digitrax guys about our modular layout and when you need to consider more boosters. Their first recommendation was to use larger gauge wire on feeders (we were using 24g on feeder drops) and they recommended going as big as we could get away with in n scale.  I suspect that *if* you have some spots with voltage drops it should be easy to correct with a few more feeders. My new ESU system actually shows overall voltage use which is nice.

Good info. I'll go with big wire.

...So, as with many things, it looks like there was another factor in play with this one extra-problematic loco and that was excessive gunk collected in the axle cups. I swapped-out the trucks with a cleaner set and this loco is behaving much better. Ran it for 3 or 4 laps trailing in a 2 unit lashup without a single dropout. Still, I have a hunch that my feeder theory may still have merit and I won't try to run a 3 (sound-equipped) loco lashup again until I add more feeders. What happened to a couple of these locos in certain spots when in a 3 unit lashup was more dramatic. Definitely more dropouts with headlight flickering in general but, in one particular (remote) spot, I saw a sort of rhythmic sputtering and flickering that looked like something that too low of voltage might cause, which I figure is probably not too good for the decoder.

[nickelplate759]

Big wire only helps up to the point where the resistance of your track isn't a major part of the problem.
For example, if you have a straight 50' run of code 55 track, a 2 amp max load, and one pair of #6 AWG feeders at one end, you'll have significant voltage drop no matter what.  You'd be better off with a bus (maybe AWG 14?) under the entire track, and lots of feeders.  If you have enough feeders to a given electrical block, AND they are short (like  a foot or so) they can be small (AWG 22 or even 24).

[tehachapifan]

Big wire only helps up to the point where the resistance of your track isn't a major part of the problem.
For example, if you have a straight 50' run of code 55 track, a 2 amp max load, and one pair of #6 AWG feeders at one end, you'll have significant voltage drop no matter what.  You'd be better off with a bus (maybe AWG 14?) under the entire track, and lots of feeders.  If you have enough feeders to a given electrical block, AND they are short (like  a foot or so) they can be small (AWG 22 or even 24).

Thanks for the info! All good suggestions I'm sure but running a bus wire system under the entire run of the track is just not something I'm going to attempt to undertake, with the crazy bowl-of-spaghetti-type layout I have with its multiple levels and all. Best I'll probably be able to do is run feeders straight out from the power source to various points along the track every X number of feet yet-to-be determined. It won't be anywhere close to having a feeder per every length of flex-track, like I know some folks recommend or do. I'd be under the layout for weeks! I'm thinking of adding feeders maybe every 8-12' or so.

[peteski]

This is actually what has kept me from pulling the trigger on getting one. I look at all the markings, settings, etc., on them and have absolutely no idea what any of it means.

How do you think I felt the first time I held a multimeter in my hand? Sorry, if you decided to jump in and start doing your own custom decoder and lighting installs, you really have to learn some basic electric and electronic theories and lingo. Really.  It will make your hobby so much easier (even if the meter looks complicated). You usually use only few of all those multiple settings..
And as far as learning how to use a multimeter, the help is as close as Google. Just look for "how to use multimeter" and you'll see lots of tutorials. Here is one: https://learn.sparkfun.com/tutorials/how-to-use-a-multimeter

Of course, if you get stuck, there are several electronically-literate members here who I'm sure are willing to help out.

And get that digital caliper too. Once you have those tools and get acquainted with them, you will wonder how you ever got along without them. 
Come on, these tools cost less than N scale boxcars. 

[peteski]

We were talking to the Digitrax guys about our modular layout and when you need to consider more boosters. Their first recommendation was to use larger gauge wire on feeders (we were using 24g on feeder drops) and they recommended going as big as we could get away with in n scale.  I suspect that *if* you have some spots with voltage drops it should be easy to correct with a few more feeders. My new ESU system actually shows overall voltage use which is nice.

Jamie, sometimes overkill is not needed or desired. Especially in N scale. I got tired of hearing the "always your as heavy wire as you can" advice, so I did some research. I recommend reading https://www.therailwire.net/forum/index.php?topic=39373.msg480748#msg480748

24AWG wire is IMO more than adequate. Unless you are running 6-sound-equipped-loco lash-ups and the feeders are several feet long.  It is the bus wire that you need to make sure uses heave gauge wire.  My NTRAK club runs DCC using standard NTRAK wiring on roughly 20'X30' (or larger) layouts and we don't have voltage dropouts.  Of course, by design, the track is fed at least every 4' (most often even more frequently).