Advice required please on dual controllers and isolating sections

Hello Russell,
Happy New Year and welcome to the forum!

Totally agree with HRF above, Hornby points are insulfrog which makes life 100% simpler! I have been modelling 40 years now and still use insulfrog points, like you I don't understand electrics, but this hasn't detracted from my enjoyment of the hobby.

From your post the layout you are building is for your children, my advice therefore is to keep it simple so that trains will run and that will keep their interest. If you go off into the realms of sectioned track, and that means soldering contacts onto the rails, the likelihood is that thing will go wrong, trains will stop, and the children will find playstation more interesting (ahhhhhhh).

I describe myself as a well "below average modeller", and having the electrical, and mechanical, aptitude of a dead frog, the adage of "keep it simple stupid" works for me. No detriment to anybody else, indeed I am in awe of the excellent sectioned layouts that appear in the MR press, and on this forum, not to mention the excellent capabilities of DCC, but I honestly don't think I could master the complexities.

From your trackplan, the two feeds indicated will make the layout function fine, indeed a third controller on the very inside track could make 3 trains run at the same time, that's just what I would have wanted as a little lad! HRF's advice is good with the points switched either controller could feed a section of either loop, so be careful, but your plan is sound and will get 3 or possibly 4 more people interested in an excellent hobby, due entirely to the purchase of a train set at Christmas. Well done!

Happy modelling (and that is what it's all about!)

regards,
Clive

Happy New Year to everyone as well. Thanks for the prompt advice so far - much appreciated. My main concern was if I had the middle loop set with the points to send a train out to the outer loop (in clockwise direction on 1st controller) and I also had a train running on outer loop (via 2nd controller) in the same clockwise direction that the outer track would have 2 controllers feeding into it. It wasnt that well drawn in diagram but I was planning to have first controller on inside loop having a power clip joining it across to middle loop so I could potentially use the same controller to run 2 trains, one on each loop - this power clip seems to be a standard feature of the track extension packs you can get to extend the standard small packs currently available. My big difference is a third loop and 2 controllers! I'm worried it might be even more dangerous if I had a train on outer loop running in anti-clockwise direction so power was been sent into the inner loop in different direction to the power flowing out of it from 1st controller with trtain trying to leave middle loop in clockwise direction. I too believe in 'Keep it Simple Stupid' so the simplest, but interesting, layout without risk of short circuiting the equipment and blowing up engines or controllers/transformers!

Regards

Russell

QUOTE (Brian Considine @ 2 Jan 2009, 08:09) <{POST_SNAPBACK}>Hi Russell,

If they are transformers then my remarks still hold, however, if they are switch mode type they should be OK from the mains side - i would ask Hornby for advice in this case.

*** I don't mean to offend but are you really sure about that Brian - Given the conventional method of DC transformer / controller construction I have never seen that possibility: Use of a direct mains path to the layout wiring never exists and in the case of Hornbys trainset controllers they are usually a 12V black box and a "wall wart" that is by its very design, double insulated.

The only common DC wiring controller problem I see is when people try to use two controllers off a single transformer, and thats at potential conflict at the secondary side, not the primary.

regards

Richard

Hi All

I think Brian has quoted what is in the Fleischmann Instructions which does make sense with conventional transformers

Connecting the controlled outputs to the same bit of track if the second transformer is not plugged into the mains - mains voltage is induced from its secondary windings to its primary windings then to the plug

but remember its not the volts but the amps that kill but the more volts the less amps required to be lethal

With my old Analog layout I had two main parallel tracks(up line and down line) each wired to a different controller and used Isolated joiners on both rails if tracks went from one to the other. and a third controller for a marshalling yard.

Much easier with DCC - Up and down line connected to the bus with the same polarity , loco's can go from one to the other if need be with out any fancy wiring ( just have to watch out for the head on collision )

Regards

Zmil

** Wow - New information like that is interesting but surprising. Are you serious? and that gets safety approval???

Mind you if the design rating of the system is 1 amp we are talking .05 of an amp but even so it is simply silly for it to exist as an issue at all... it doesn't need to.

In any sanely designed controller is simply shouldn't be possible! Proper rectification and input circuit design is enough to prevent it 100%... It certainly doesn't apply to any other controller I have seen or worked on and wouldn't pass any safety regulation here, UK or EU for the past 20+ years surely?

Richard

RichardQUOTE (zmil @ 2 Jan 2009, 12:56) <{POST_SNAPBACK}>Hi All

I think Brian has quoted what is in the Fleischmann Instructions which does make sense with conventional transformers

Connecting the controlled outputs to the same bit of track if the second transformer is not plugged into the mains - mains voltage is induced from its secondary windings to its primary windings then to the plug

but remember its not the volts but the amps that kill but the more volts the less amps required to be lethal

With my old Analog layout I had two main parallel tracks(up line and down line) each wired to a different controller and used Isolated joiners on both rails if tracks went from one to the other. and a third controller for a marshalling yard.

Much easier with DCC - Up and down line connected to the bus with the same polarity , loco's can go from one to the other if need be with out any fancy wiring ( just have to watch out for the head on collision )

Regards

Zmil

QUOTE (russell vale @ 1 Jan 2009, 20:52) <{POST_SNAPBACK}>....My main concern was if I had the middle loop set with the points to send a train out to the outer loop (in clockwise direction on 1st controller) and I also had a train running on outer loop (via 2nd controller) in the same clockwise direction that the outer track would have 2 controllers feeding into it....

This should be fine, but remember that both trains will travel according to the highest power setting, (which doesn't mean the trains will go at the same speed!).

QUOTE (russell vale @ 1 Jan 2009, 20:52) <{POST_SNAPBACK}>....I'm worried it might be even more dangerous if I had a train on outer loop running in anti-clockwise direction so power was been sent into the inner loop in different direction to the power flowing out of it from 1st controller with train trying to leave middle loop in clockwise direction.....

If you applied the power in opposite directions with the points set to cross between loops, both trains should stop or be reduced to a slow crawl (electronics is not my strong point, but going from experience this is what will happen), a drastic reduction in speed could see derailments though (through momentum).

QUOTE I did come across a case some years ago with two conventional controllers where both had faulty rectification & the mains fuse was blowing - this is the senario that I am talking about.
This is the only circumstance by which this extremely unlikely scenario could arise.
It is unfortunate that so many people still tend to use the term 'transformer' when they really mean 'DC controller'.
Certainly if two actual transformers were to be connected together by their secondaries the 'free plug' effect could arise.
However, the controller devices we are talking about here generate a DC output, therefore in principle cannot cause AC to be reproduced in a second unplugged unit. The rectification prevents such a situation arising - unless both sets are faulty.
Having said that, I suppose that two 'variable transformer' type unsmoothed DC controllers (H&M Safety Minor or Powermaster, for example) might just have enough residual AC waveform at their interface to cause some secondary induction to take place, possibly giving a low level distorted waveform at 100Hz at the free plug. Must give it a try!

Hi All,

Update for all of you and also if new members in future are looking for similair answers they can see the history and conclusion of this topic to help them out - like other previous posts have done to help me get this far!

Thanks for all of your answers. Looks like I started quite a debate! Anyway I went into my local railway model centre and asked them to validate my design with dual controllers. I wouldn't say they spent a long time looking at the design and following the logic through but they recommended the 2 isolation sections I had mentioned in my diagram. They recommended a cheaper Peco part number - ST205 - that is same length as standard Hornby R600 straight but has a built in isolator switch that you move to open or closed. Only costs about £2.80 as opposed to probably about £6 to get official Hornby R618 isolator straight and then need to buy extra £4 switch to go with it. Downside to Peco isolator straight is you can't wire it into a motorised switch like you can do with Hornby one. For my young kids having a manual solution that is kiddy proof is perfect!

Anyway I brought 2 of these Peco isolating straights and built my track as per the diagram (with a few minor mods to the directions of some of the sidings/points) and am happy to say it works very well with the capability of moving the train between the different loops/controllers with keeping the power going in the same direction (i.e. have trains going in clockwise direction on both inner and middle loops and then changing points so that outer train joins middle loop and it moves across seemlessly and keeps going OK, along with original train on middle loop. This is with isolator switch set to off. This also works in reverse direction by changing power direction and moving trains from middle loop to outer loop /controller. If I want to though I can stop supplying power to other loop and then open the isolator manual switch and the train can move to other loop and remain powered by same controller (like it would do on a standard single controller system).

I wasn't brave enough to have a train move between loops and have the power going in opposite directions (clockwise and anti-clockwise) to see what damage that did to train with it keeping to want reversing direction as it moved over isolation straight and trying to go back to track loop it has just left!

Anyway the upshot is after all this testing my house electrics havent blown, both controllers/transformers still work and the engines I'm using still work so thats a good start! Hopefully this is by (electrical) design and I'm validating this properly and haven't got lucky (or shortening the life of my equipment with it gradually destroying something because I have go t the power feeds wrong!)

Now to build the track onto plywood and commit to the design by wacking in the track pins and painting the board/underlay areas accordingly. This is the difficult and time consuming step!

Many thanks for all your responses. It defintely gave me the confidence to carry on with my design and do some (potentially destructive) testing!

Regards

Russell

QUOTE (Brian Considine @ 2 Jan 2009, 18:39) <{POST_SNAPBACK}>Also the same with Gaugemaster controllers as well !

I did come across a case some years ago with two conventional controllers where both had faulty rectification & the mains fuse was blowing - this is the senario that I am talking about.

The Other scenario is if an inexperience user connected the uncontrolled output of both Transformers to the same track
and left one unplugged in the Mains -No rectification in the circuit.That would be lethal at the unplugged mains plug

Some of the labeling of controllers is not the best

Regards

Zmil

QUOTE (zmil @ 6 Jan 2009, 12:52) <{POST_SNAPBACK}>The Other scenario is if an inexperience user connected the uncontrolled output of both Transformers to the same track
and left one unplugged in the Mains -No rectification in the circuit.That would be lethal at the unplugged mains plug

Some of the labeling of controllers is not the best

Regards

Zmil

Now are we talking about uncontrolled AC or DC output from transformers? I would not think that anyone would connect the output from a transformer direct to track twice if using 2 transformers without testing the that the loco ran when the controller was operated. Surely if the loco did not work using the one controller, one would look at instructions first before even considering attaching another set of wires to the same track! Note I am differentiating between transformer & controller here - 2 different beasts. Normally all outputs on commercial controllers are protected internally & I would hope they worked if 2 straight power souces - uncontrolled was connected to the same track if the wires got reversed. Certainly controllers if DC got connected between each other, you would have to have both sets of rectification fail to allow the secondary AC from transformer #1 to get into the other controller transformer #2 to generate a voltage on the primary side of the un-plugged #2 unit. If using modern transistorised controllers, I think that would preclude that happening even more so.