DCC 009 track droppers

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EMee
Posts: 3
Joined: Wed May 29, 2024 11:45 am

DCC 009 track droppers

Post by EMee »

Hi, basic advice please. I've read a huge range of views as to how many droppers you need on a layout. My layout is a simple oval with one passing place. It's DCC using a horse shoe shape bus wire. I'm using PECO 009 track and some pieces are very short. If I wired every piece of track it would be every 10cm or so in places (good practice for soldering I suppose!). Could I stretch to every .5m? The whole track flat worked on test using the one prewired dropper. I have an incline so thought I should probably have them a bit closer together for that.

Thank you.
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Mountain
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Location: UK.

Re: DCC 009 track droppers

Post by Mountain »

First, may I say that some simple layouts do not need that many droppers at all but natrually the more one adds, the less likely one will have dead spot issues.

Now for a simple basic oval or circle of track as supplied in trainsets, one can get away with just the two wires from the controller to the track, be it DC or DCC. But with DC, any small distractions in current will be less noticable as the momentum of the motor will over-ride the dead spots as long as one has sufficient speed to carry the train over any slight dead areas.
But with DCC we not only have DCC signals carried through the rails as well as the locos operating current, but also we have things like inertia (Along with back EMF) which if they sense a moments brake in the current will throw the decoder into thinking it has to start its inertia all over again as if the loco is stationary. It is why a temporary solution would be to turn the inertia (And back EMF) settings to "Off" (Or zero or whatever is the lowest setting) on the locos decoder.

Now the real solution is to try and eliminate all potential dead spots on our track which is why with DC we provide additional dropper wires to give ourselves the maximum means to eliminate every potential dead spot we can find, and do our best to provide additional pick-ups on any loco we have that may be lacking.
The issue is we need to be practical as well as one can take things to end up with every single piece of track having a dropper and every single wheel having a pick-up to the point that there is so much resistance on our wheels with all those pickups that we ovefstrain our motors and so much additional weight in wires that we could in extremes warp our boards! (Obviously I am taking things to extremes, but in an ideal world, a very simple oval only really needs two wires if our railjoiners are making the electrical connections that they should).

So how far we go is up to us... DC'ers can get away without so many droppers so may chuckle at times and think DCC'ers are taking things to the extreme, but at the end of the day, we just want our trains to run, so clean track, wheels and extra droppers to aid running can't be a bad thing.
Just how many droppers? Every other metre, or every metre, or every 25cm? If we use yard lengths (Yard is about 90cm) of flexi-track then we may decide to solder droppers on every second or third piece of track. If we have sectional track with shorter pieces then we may go for a few more BUT generally, sectional track should in theory need less droppers because it is less likely to move. Flexi-track can have a little extra movement at the rail joints... Though all track expands and contracts which is more noticable around the rail joints, but there again, if we glue ballast down then the track is held more rigidly which can in theory prevent some issues but create others if taken to the extremes...
Peterm
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Joined: Fri Nov 09, 2007 1:26 pm
Location: Bribie Island. Australia

Re: DCC 009 track droppers

Post by Peterm »

Don't worry about how small or big a layout is. A pair of droppers for every piece of track including points and crossings is needed if you want fault free running. Rail joiners aren't reliable conductors.
Pete.
Bigmet
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Joined: Tue Aug 14, 2007 2:19 pm

Re: DCC 009 track droppers

Post by Bigmet »

EMee wrote: Fri Jun 07, 2024 4:11 pm ...I'm using PECO 009 track and some pieces are very short. If I wired every piece of track it would be every 10cm or so in places (good practice for soldering I suppose!)...
Pragmatist approach.

Does the layout work to your satisfaction as it stands? If so leave as is, but be aware that you may have to revise arrangements in future. If your intent is to replace or significantly alter the layout then you can improve the wiring as you go.

Learning point.

There's a reason why both kit built track and commercial flexible track, both with rail in yard lengths, is so popular among keen layout builders. This was the case long before DCC came on the scene! In particular, layouts that were intended for exhibition had soldered on electrical connections to every rail length in order to secure reliable current supply. (Also, a yard length is - by happy chance of the expansion characteristic of nickel-silver - 'just right' to compensate for temperature variation if laid with a 1mm gap!) All my own layouts have been built this way since learning this useful information in my teens.
EMee
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Joined: Wed May 29, 2024 11:45 am

Re: DCC 009 track droppers

Post by EMee »

Thank you for your replies. As I've read, there are certainly different opinions. I will probably go for quite a few droppers but not every piece of track.
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