Short Circuits = Short Fuses

Digital Command Control - or DCC as we have all come to call it - is a wonderful thing, but let's not pretend it doesn't have a lot a downsides.

Many might regard the cost of the chips as the biggest drawback, which is especially the case when you're going for sound as well, because it can sometimes double the price of a new locomotive.

Then there's the complexity of the control handsets themselves.  

A couple of times during the Glasgow show I looked across at some of my fellow operators and saw only furious button pressing and furrowed brows, and no trains moving.....

And at exhibitions I would argue that perhaps the biggest issue is the way that everything on the layout comes to a stop as soon as anything creates a short circuit.

Mostly this is because of simple human error - a failure to check the route has been set before moving off and the loco runs towards point which are set against it.

The problem is affects everything on the system, not just the single train involved.

But as the weekend in Glasgow wore on we began noticing an increasing number of mysterious occasions where a train made up of our set of 'Barn' carriages would come to a stop in the middle of plain track for no apparent reason.

The instinctive reaction each time would be to assume a short had occurred somewhere else on the narrow gauge side of the layout.

(Minffordd is divided into two separate circuits for 009 and 00)

The fiddle yard operators, and the person on shunting duty on the remote controller at the front, would face increasingly irritable accusations and interrogation.  "Was that you, again??!"

By the Sunday afternoon it had happened so often - and there had been so many false accusations bandied about - that the finger of blame started to be pointed at the train itself.

But how?

It was Himself who did the detective work and found the culprit.

It was carriage 14 what did it!

Here's the explanation.

The wheelsets we're using on these carriages are insulated on one side only, which means that on a bogie you need to have both orientated the same way if you are not going to risk creating a short circuit,

This is especially the case when the bogie frames are brass, and the axles fit into brass bearings, because the whole bogie becomes live.

We'd taken care to ensure each bogie on the set had the wheelsets matching.   

What we hadn't done was check that every bogie on every carriage matched.

On carriage 14 we had the wheelsets in the bogies the opposite way round to the rest of the rake.

With us also using brass couplings soldered to a brass bogie, the last line of insulation defence is the paint on the couplings.

As that begins to wear and chip after 3 days of intense running at a show, snaking over crossings and into fiddle yard sidings hundreds of times, it opens up the potential for the different polarities of bogies on adjoining carriages to briefly come into contact with each other, creating the short circuit.

It's simple fix to rotate the wheelsets on the bogies on 14 to they all match now, but it shows how careful you have to be.

Tunnel Technology

"Tunnel collision is the worst to be feared, Sir".

So explained the title character in Charles Dickens' famous short ghost story 'The Signalman',  and everyone with a model railway knows that's just as true in miniature form!

The real Minffordd doesn't have a tunnel, of course, but we had to bend reality - in all senses - to make the Cambrian section of our layout into a complete circuit.

In the Porthmadog direction the line goes under a bridge, which is thereabouts in real life, but our train doesn't emerge on the other side.

Instead it sneaks beneath the narrow gauge ramp down into the exchange yard.

What adds to the complication is that while they are under cover the trains pass over the first of the points where the storage loops begin, indicated by the arrow on the photo below.

Now, modern RTR rolling stock runs pretty reliably and these days you don't get trains derailing routinely on turnouts.  

Except, of course, where there's human error and one of the operators changes a point while a train is going over it..........and then you're in a whole world of pain and embarrassment while you attempt to retrieve it in public.

So Himself has included a neat little piece of technology to try to prevent this as much as we can.

In the tunnel, opposite the point blades, is a light beam sensor which detects when a train is passing over the point, wired to an indicator on the control panel.

When there is a train passing in front of the sensor it breaks the beam and a corresponding LED on the control panel warns the operator not to move the switch.

I suppose it would be possible to also lash up a fail-safe so that when a train is detected power to the point motor is cut, but we haven't taken it that far.

Should all that fail, and we still somehow end up with a derailment under there, Himself has built-in an emergency access flap.

We've never had to use it.   

Yet.........

Widget

To adapt a phrase, necessity is the father of invention....

A wire on an electrical connecting socket broke the other day on my son's OO layout at my house, but the only one of us with a pin removal tool is Himself.

A Covid-compliant trip was organised to collect the said device to enable me to effect a repair (which didn't take more than a couple of minutes with the soldering iron).

No sooner did I message Himself to make arrangements to return the gizmo to him, the next time I was passing his house, he informed me that in the meantime he'd been channelling his 'inner Stefco' and come up with a homemade version, so I should keep hold of the original gear.

Now, I happen to think that's rather impressive, and worthy of a wee blog post.

Finding Faults

Himself is plugging away at the snagging list prior to taking Bron Hebog to Bressingham for Narrow Gauge East this summer.

The problem is that in trying to sort one issue you discover others.

So it was when he set up one half of the fiddle yards to try and sort an electrical niggle on the 'cab control' wiring and found that a number of the indicator LEDs on the Rhyd Ddu end panel had failed.

So he's had to open all that up to replace them.

Quite why they've failed is a mystery.

The ones in the control panel on Dduallt have lasted for more than 20 years, but after just two years in the west of Scotland climate these have gone pop!

Is there a connection?

Anyway, I thought you might also like to see a snap of the loco he's been using for testing duties.

Our original Dundas Linda, which had major surgery to its Ibertren chassis to fit it with cranks and outside frames (and a heart transplant with a Mashima motor) is still going strong.

All Under Control

Both ends, or perhaps I should say, both levels of the fiddle yard have now had the track laid and the temporary control unit for shunting in the yard, which I mentioned in a previous post, has been installed.

To me it all seems very prototypically FR.

During the push back to Blaenau - and to a lesser extend through the WHR project - the railway had a series of short term infrastructure solutions that ended up becoming very much long-term, and for all I know our fiddle yard could end up being just the same.

You can see that Himself has laid out the lower half with the same pattern of sidings as the Caernarfon end.

Eventually we plan to have the control panel for all the point work and electrical sections mounted here at the rear of the layout with the 'drivers' plugging in hand held controllers at the front of the layout where they can combine train operation with public relations duties, ie. Gassing to the punters. (I foresee collisions and derailments)

The only question mark with this temporary set up is that Himself has not been able to test that all the wiring will talk to the rest of the layout because, short of hiring the village hall, we're not able to erect the whole thing to test it.

Set up time at Woking in three weeks could be very interesting....

Splendid Isolation

There are a few tweaks needed to make the fiddle yards user-friendly for the operators at an exhibition.

If your layout is old-fashioned DC controlled, as ours is, then its handy to have some isolating sections to allow you to have two locomotives standing on the same road.

This gives you the option of either running round the train and putting same same loco back on the other end or bringing a fresh engine into the front to take the train for the return journey around the layout.

Himself has also installed the function to have a separate controller for the fiddle yard so someone can be shunting in there while someone else is taking care of the mainline.

Yes, yes, I know you could do all this and more with DCC but you're wasting your breath.

Electric String

For some people wiring their layout is the task they fear - not so on Bron Hebog.

It's not awfully complicated, as you can see....

,

If you've been reading this blog for a while it probably won't surprise you to learn that we are stubbornly DC. None of this fancy fly-by-chip DCC stuff here!

With such a simple track plan - just long single track sections, a passing loop and a siding - there are only two wires strung between each of most of the boards as you can see in the picture.

The tricky electronic spaghetti will be found in the fiddle yard if Himself decides to go down the path of automatic route setting again as we did on the yards at Dduallt, where a large bank of diodes meant a twist of a rotary switch and the pushing of a single button was all that was required to send a train in or out of a choice of 8 roads.

I seem to recall it involved a small amount of head-scratching and he hasn't said if we're doing something similar this time...

Bonding Session

I got a bit ahead of myself last week when posting pictures of the new section of track being ballasted.

I forgot to mention that before the stones are spread onto the track there's the small job of soldering the feed wires in place.

Just in case you were wondering, this layout is being built according to the quaint old-fashioned concept that the operators actually control the trains themselves rather that leaving it to digital micro chips buried deep in the locomotives which probably have more computing power than the rocket that sent Man to the Moon.

As you can see Himself is doing a very neat job, which is not surprising since he is now fully training in wiring track of all sizes as you can see in this picture of him in action on the real FR.

I did briefly consider posting this snap on 1st April and seeing if anyone would believe me if I described it as a World Exclusive revelation that the FR is not a steam railway at all but a giant electric train set.

He is, in fact, drilling and bonding new track circuit wires into position, one of the many tasks that distract him in North Wales when he's supposed to be at home building the bloomin' layout!