Voltage drop

[RAF96]

I have used topside of board Omega links across rail joints on a small layout for reliable continuity rather than go to the effort of a full bus.

 

I also used to use the extremely lo-tech thumb test to spot high resistance across rail joiners. If there is a hi-res then your thumb will feel the heat as you move it from joint to joint.

 

Rob

[AndyID]

I have used topside of board Omega links across rail joints on a small layout for reliable continuity rather than go to the effort of a full bus.

 

I also used to use the extremely lo-tech thumb test to spot high resistance across rail joiners. If there is a hi-res then your thumb will feel the heat as you move it from joint to joint.

 

Rob

 

Nothing wrong with that for short distances although with a bus you only have to solder one wire to each rail section rather than two. The disadvantage of course is that you then have to connect the droppers to the bus wires under the baseboard.

 

For longer distances the voltage drop along the rail itself is quite significant. The voltage drop at half an amp along ten meters of Code 75 N/S rail is 1.36 volts, and that's the total (out and back) rail length. The distance from the power feed is only five meters.

[RAF96]

Nothing wrong with that for short distances although with a bus you only have to solder one wire to each rail section rather than two.

The disadvantage of course is that you then have to connect the droppers to the bus wires under the baseboard.

Exactly why I said a small layout, where rail resistance is insignificant.

 

Look again at Omega links, one to each rail, then again at the other end, ad infinitude, so no more connections than required for a linear bus in toto as each pair of rails shares its links with the next and for a closed loop the first pair are also the last.

Rob

[AndyID]

Look again at Omega links, one to each rail, then again at the other end, ad infinitude, so no more connections than required for a linear bus in toto as each pair of rails shares its links with the next and for a closed loop the first pair are also the last.

Rob

 

Quite so, but Tiger said he was was having some difficulty soldering wires on to the rails. With bridging loops he has to solder two wires to each piece of rail - one at each end. With a bus system he would only need to solder one wire to each piece of rail.

[tigerburnie]

I'm perhaps not explaining this very well, as I'm not running DCC, I cannot have all the rails fed "live" as I would have locos moving that I don't want moving. My plan was to have sections fed via a switch to isolate the areas, which I was planning to connect via wire loops to remove any reliance on the rail connectors, thus removing heat problems or poor continuity problems. Each section is to have one feed to each rail group(these are in between points at each end) with the live feed going through a switch. I have most of the components to start this work, I will take some images so you can see what I'm doing and comment if you think I am making any mistakes.

[tigerburnie]

On the up side the down fast would have a single feed with the live via an on/off switch, ditto for the other "loops. This is only for the station area, the main twin track loop will be made from metre long sections with a feed to each from a bus wire.

[AndyID]

Hi Tiger,

 

From the pics you posted it looks like you are using "insulfrog" type points. Is that correct?

 

I'm assuming you want to use the point settings to isolate the various loops so that you can hold trains in them. Is that correct?

 

I'll post a suggested wiring diagram - might take me a little time.

 

Andy

[tigerburnie]

Hi Andy, yes that is correct insulfrog points and the loops will at times have locos on them as per the prototype, so rather than just rely on the points for power supply, each line will have a switched common supply. The up line will all be fed from a terminal block fed from one side of the controlled supply and the down line on the other controlled supply(gaugemaster). This is just for the station area only, the main oval track will be insulated and fed by a seperate controlled bus line from another controller. In effect the whole idea of the switched feeds is to overcome any faulty joins between the pieces of track. Tonight I have soldered wires to the bottom of rail joiners, drilled holes in the baseboard and started to run these short cables(2 feet maximum) to terminal blocks which will be switched on the live side, so in effect if I open the points the line will be live, the direct feed to the rail joiners is a belt and braces to give a better supply. Does this make sense?

[AndyID]

Thanks Tiger,

 

I think get it, but you might possibly be making it a bit more complicated than it needs to be.

 

It's difficult to properly describe this stuff in words. I'll try to come up with a basic diagram and we can take it from there. That way other contributors will be able to identify any problems/improvements.

 

Andy

[AndyID]

Maybe something like this?

 

 

Leicester1.pdf

 

Also attached as a PDF which should be a lot clearer.

 

 

[AndyID]

We can also simplify the diagram a lot if we accept that all the rails nearest to the controllers are bonded to the common return.

 

 

And in PDF

 

Leicester2.pdf

 

 

 

 

[tigerburnie]

Made a start on wiring the station and building the work station for the controller, this slides in and out to give easy access and can disappear when not required(reducing the dust too I hope). The idea is to keep up and down lines on separate feeds(the way I've done it including the 0 volts as well) there will be 6 feeds from each terminal strip to feed the sections of track, connected with wire loops and switched positive lines so that all the lines are not live at the same time(hence not using a bus line).

 

[tigerburnie]

Track connections and feed are via soldered wire to the peco connectors, these may be soldered to the rails as I have left room so as not to melt the sleepers

 

[tigerburnie]

A rather blurry overview of the station track work, a lot of soldering and drilling to do, I am adding additional links now, that can be connected up later if required should the connectivity deteriorate over time. The large gaps will be dealt with after the soldering of the links is completed, so as not to melt the sleepers.

Edited July 17, 2017 by tigerburnie

[kevinlms]

Track connections and feed are via soldered wire to the peco connectors, these may be soldered to the rails as I have left room so as not to melt the sleepers

Sorry to say, but the top track on that photo looks like the track doesn't line up too well. A recipe for derailments, I fear.

[Free At Last]

I can see that hanging the boards vertical around the loft would give a lot more room but are you using some form of 'Magnadhesion' on the stock to stop them falling from the tracks?

Edited July 17, 2017 by Free At Last

[AndyID]

A rather blurry overview of the station track work, a lot of soldering and drilling to do, I am adding additional links now, that can be connected up later if required should the connectivity deteriorate over time. The large gaps will be dealt with after the soldering of the links is completed, so as not to melt the sleepers.

 

Kevin is right. The alignment of the track at the turnout nearest the camera in the second shot is going to lead to disappointment. When you have to add a short section of track it's best to arrange for it to be in a straight (if at all possible).

 

I don't see any section breaks. It would be much simpler to add them as you are laying the track.

 

Soldering the wires to the joiners rather than the rail is likely to lead to problems when the joiners loosen up and oxidation sets in, and if you solder the joiners to the rails you are likely to have expansion problems in the future.

Edited July 17, 2017 by AndyID

[tigerburnie]

Nothing is fixed down yet, still adding connections, too hot to work up there today. Still a bit of jig sawing to do as well, so most if not all this track may be removed and final fitted. Maybe the blurry one would be better rotated through 90 degrees.

[tigerburnie]

Slow progress at the moment, but things are moving along, north end is now stuck and wired, but not all loops across the rail joiners are completed. Feeds at both ends from the controller is showing full voltage across the whole area, with out the switched feeds connected(waiting for miniature switches to be delivered). So the belt and braces switched feed to each track is at present not required, however taking on board what people advise regarding corrosion/deterioration over time, it's comforting to know I have a cunning plan in place to sort of future proof it a bit. Had a quick test running an A3 with coaches attached in all directions and after a couple of re-fits, no de-railments which is a bonus.

[AndyID]

 Feeds at both ends from the controller is showing full voltage across the whole area

 

Were you drawing any current from the controller when you measured the voltage? If there was nothing to put a load on the controller you won't see any voltage drop at all, even with bad connections.

[tigerburnie]

No Andy, thanks for that, I should have known that, I first did a continuity test and then just put the power on and switched the tester over to voltage, I should know better really doh!.

[Junctionmad]

I have always worked on the basis that no rail joiner carries current . Hence droppers to every continuous piece of track , DC or DCC makes no difference

[tigerburnie]

I will have feeds to every section, just the station area will have locos on most of the passing loops at certain times in the timetable, so having switches to turn off the supply means locos will only move when I want them to. The switches arrived yesterday and I've mounted them on a panel ready for wiring, I'll try and take some pictures that might explain what I'm doing.

[DCB]

Made a start on wiring the station and building the work station for the controller, this slides in and out to give easy access and can disappear when not required(reducing the dust too I hope). The idea is to keep up and down lines on separate feeds(the way I've done it including the 0 volts as well) there will be 6 feeds from each terminal strip to feed the sections of track, connected with wire loops and switched positive lines so that all the lines are not live at the same time(hence not using a bus line).

Wiring looks good, your separate returns for up and down lines will pay dividends later on, I made the mistake of using common return for all of one station area of a layout and the mental gymnastics required to understand resulting weird faults was challenging. Much easier when you can put isolators and switched feeds in either polarity rail.  As a rule of thumb, The smaller each "Section" or "Power zone" the easier it is to locate a fault and the more time you spend playing trains and the less fault finding.

 

Track connections and feed are via soldered wire to the peco connectors, these may be soldered to the rails as I have left room so as not to melt the sleepers

Those wired fishplates look so ugly, how will you disguise the gap when there is no room to slide a dummy sleeper under?

 

A rather blurry overview of the station track work, a lot of soldering and drilling to do, I am adding additional links now, that can be connected up later if required should the connectivity deteriorate over time. The large gaps will be dealt with after the soldering of the links is completed, so as not to melt the sleepers.

Check photo of the real station.  Tracks are usually paired with [Edit] a "6ft" way between the tracks as in up and down lines on plain double track and a [Edit] "10ft" way between the pair of running lines and sidings loops or another pair of tracks.  I didn't realise this until the layout was too far advanced to change it and it now annoys me.   No reason you can't carve lumps off points to optimise track work. I cut off the end of tie bars and trim sleepers in addition to sawing lumps off the end of points to make the track flow and to avoid short filler pieces as far as possible. I really hate short filler tracks, they never stay flat and look horrible.

 

The voltage drop thing is interesting, I'm starting to think the people with voltage drop problems need to get a decent controller. One which controls voltage. Not wattage.

Edited July 30, 2017 by DavidCBroad

[Fat Controller]

Wiring looks good, your separate returns for up and down lines will pay dividends later on, I made the mistake of using common return for all of one station area of a layout and the mental gymnastics required to understand resulting weird faults was challenging. Much easier when you can put isolators and switched feeds in either polarity rail.  As a rule of thumb, The smaller each "Section" or "Power zone" the easier it is to locate a fault and the more time you spend playing trains and the less fault finding.

 

Those wired fishplates look so ugly, how will you disguise the gap when there is no room to slide a dummy sleeper under?

 

Check photo of the real station.  Tracks are usually paired with a "4ft" way between the tracks as in up and down lines on plain double track and a "6ft" way between the pair of running lines and sidings loops or another pair of tracks.  I didn't realise this until the layout was too far advanced to change it and it now annoys me.   No reason you can't carve lumps off points to optimise track work. I cut off the end of tie bars and trim sleepers in addition to sawing lumps off the end of points to make the track flow and to avoid short filler pieces as far as possible. I really hate short filler tracks, they never stay flat and look horrible.

 

The voltage drop thing is interesting, I'm starting to think the people with voltage drop problems need to get a decent controller. One which controls voltage. Not wattage.

I agree about making sections relatively small; easier to find faults by systematically re-feeding.

BTW, the 'Six-foot' is within pairs of running lines, 'ten-foot' for the gap 'twixt adjacent pairs, or between running lines and loops or sidings.