DCC and the geriatric modeller.

Locos getting lost when they hit dirty track is something I have occasionally experienced (usually a change in the input fixes this, speed down or up). The other faults you describe I have not really experienced, I'm running a decent sized DCC layout and using DCC has undoubtedly saved me a ton of wiring hassle. I am using Lenz, though, not Hornby.

You can certainly change the acceleration and deceleration behaviour of your locos, but a quick look at the prototype will suggest why they are set where they are. Guy

The other faults you describe I have not really

The parametre changes to locos is not a problem except that the overlong decellerations possible do not really scale into model systems unless they too are very large. The problem is the wheel width on DE outline models (the most recent are no different than those 30 years old or more). The only possible permenant remedy is to line the check rails with 10 thou material but I find it difficult to fix in some cases. This remedy also plays havoc with some of the longer 6 coupled steam outline models. The double slip mentioned would need to be double isolated on each inlet/outlet and then a relay / c.o. sw inserted to mimic the route selection. So, the only savings so far have been in isolating switches for power supply as each point isolation calls up further power wiring.

The big red "stop" button is really necessary if several locos are in action as a runaway can keep going as long as power is on the track section whereas with a well designed DC layout there will be dead sections where the block ends. I see why the MERG chaps inevitably revert to the use of a PC to watch over things.

I do this anyway as it reduces derailing on points. I use 10 thou strip, trimmed to length and superglued in place using thick superglue. I wedge the plastic tightly onto the checkrail using wedges made of matchsticks while it sets and to ensure it stays in profile.

Only on tight radii IME, but I do check the back to back of every axle. I don't have any points under the Peco medium radius.

I have insulfrog double slips that have no special wiring or switching at all. I have some electrofrog three-way points, I used electrofrog deliberately because they are in sidings so will have slow-running shunters running over them. The wiring is still pretty simple, the outer track is always one polarity, checking continuity is a doddle. My layout will have over 100 sets of points when complete, it's well over 70 now, about half and half electrofrog and insulfrog.

To be honest I would put a stop button in any layout that permits multiple locos, because you might be at the wrong controller when something unexpected happens. I don't feel a need for a PC but my layout is not that large, only about 100m of track. Guy

Disable DC operation in the decoders to stop the runaways.

These generally happen when the decoder can't see valid DCC data, due to dirty track or noise cause by the temporary shorts, and switches to DC operation. The fact that DCC always has full voltage on the track then causes the loco to run away at top speed. It's not necessarily the loco causing the short that runs away.

There's plenty on the web about insul- v. electrofrog and switching frog polarity, with equally vociferous advocates on all sides ;-)

MBQ

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That is an interesting observation! Just how does one cancel the "0" address?

So far insulating the branch outlets and thickening the check rail has been successful but the reuse of track and fittings means that I have to test and re test each installation. I also am finding that b-b settings simply have to be varied to suit some of the more complicated pointwork ( peco 3 ways etc).

Snipped

The 0 or 00 address is normally used by some DCC systems (not Gaugemaster Prodigy) to operate a loco which does not have a decoder fitted. I have never seen such a loco "running away" and cannot understand why anyone would try to address a decoder as "0"

Dave W.

That's a different thing. Selecting address 0 on the throttle is a convention to tell the command station to stretch parts of the DCC signal to give it a DC bias and drive a DC loco with no decoder. It's not recommended and not supported by all systems.

Convertion to DC operation in the decoder applies regardless of the address and is supported by most decoders. It's controlled by one of the bits inb CV29. I don't know if the select allows you to change this.

MBQ

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You are not cancelling the "0" address at all. In fact the opposite. Address 0 on a controller is used when you have a non-decoder equipped loco on your DCC system. It's not recommended.

Most decoders (I think it's an NMRA standard, so perhaps all) can be used on DC systems by simply putting the loco onto a DC or analog layout. The decoder senses that it is not a receiving DCC signal, and so allows the current from the rails straight through to the motor.

What can happen on a DCC system is that for various reasons the decoder thinks it must be receiving DC, with obvious consequences with

15v on the track. On my system (EasyDCC) this happens most often at power up, when the booster might fire up before the control unit.

The solution is to set bit 3 in CV 29 off. That bit is defined as "Analog mode conversion" - 1 means the conversion is ON, 0 means it's OFF.

Unfortunately I can't help you with instructions for setting bits in CV29 in a Select system. Is that Hornby?

John

The real solution is to fix the poor design of the booster.

ZTC recemmended an isolating switch between the booster and the track to be opened during power-up/down for a similar reason.

MBQ

Perhaps. Although if ZTC make that recommendation then it's not just the odd one or two systems which see the problem. In my case my locomotives will never run on a non-DCC system, so unsetting that bit was a no-brainer. In a a couple of minutes all locos were done, cheaper and quicker than installing an isolating switch. Which in my case now would be three switches between three boosters and the track.

John

I do so wish that I could have gleaned these gems earlier!

Careful observation shows that passing shorts (at the frogs) trip the controller through 11,30 and settling out on the default 03 as in start up. The effective process being a restart. This leaves power on to the selected decoder which cannot be reselected and controlled until the sequence has expired, the decoder selected and the speed control changed! This is sufficient time for my test loco to have run off the end of the track! Putting the controller back to zero speed does not help as the decoder has to be put in contact with the controller first and then switched down to zero speed so that demands the use of the big red stop button. As I have 5 removable sections planned it looks as if some safety interlocking to prevent attempted space launches will be necessary.

I suspect that this a problem with your system, and/or the decoders you are using. Operating on two or three different systems has not seen a short circuit result in that sort of behaviour. If your getting shorts at frogs then perhaps the frog should be isolated, and powered through a switch which operates in conjunction with the point, so that power to the frog is always at the right polarity. I have done that on all my points (although I also did that prior to switching to DCC, as running narrow gauge to locos are a little small, and stalling on the frog was a possibility.

After setting all my decoders so analog control is disabled, the only runaways on my layout were when operators unplug a throttle while a train is moving, and then try and stop the train without plugging into another socket. Now with wireless that's a thing of the past...

John

: As I have 5 removable sections planned it looks as if : some safety interlocking to prevent attempted space : launches will be necessary.

A sensible idea anyway, regardless of control system, surely?!...

Again, poor design of the controller. It sounds to me like the controller is taking too long to detect the short and the power supply is collapsing or shutting down first so that the whole Select does a power on reset.

Better systems have (internally) a current limited supply for the track and a separate supply for the control electronics. When a short occurs the track power is removed for a short while and then re- applied. The process repeats until the short is removed and the power stays on. During this time the control electronics retain the state they were in and control of locos is not lost.

Even the cheap Bachmann EZ Command works like this. My favourite trick is running a loco into point set against it. The short causes an audible ticking sound as power is alternately applied and removed. As soon as the short is fixed the loco carries on as normal, under full control.

Don't let your experiences put you off DCC in general. I would join one of the Yahoo groups, such as DCCUK.

MBQ

I took your advise regarding DCCUK and found that the frog shorting is a common problem which produces problems in both controllers (almost all types) and some of the chips. Few if any of the members admit to using such cheap kit as I chose to start with but all seem to have some axe to grind. My little select does not have any other vices except those discussed here and my mix of Hornby & bachmann chips seems to be a happy one if I discount the early chip failure. The simplest and most economic solution is indeed the control of checkrail gaps and does give the option of keeping the switch rails live to prevent relying on blade contact for power.

Peter A

I took your advise regarding DCCUK and found that the frog shorting is a common problem which produces problems in both controllers (almost all types) and some of the chips. Few if any of the members admit to using such cheap kit as I chose to start with but all seem to have some axe to grind. My little select does not have any other vices except those discussed here and my mix of Hornby & bachmann chips seems to be a happy one if I discount the early chip failure. The simplest and most economic solution is indeed the control of checkrail gaps and does give the option of keeping the switch rails live to prevent relying on blade contact for power.

Peter A

======================= Nothing wrong with the select if you accept its limitations. Very simple system, great for basic stuff - all most people want - excellent for children, and if you do get into DCC and decide to upgrade then its a backup. I use one to control points and let child try to destroy set up. Bought (unused) second hand for GBP30.

Cheers, Simon

I don't see any messages about this subject on DCCUK.

MBQ

: I took your advise regarding DCCUK and found that : the frog shorting is a common problem which produces : problems in both controllers

I guess that must a common problem on garden railways, frogs sitting on the track and causing a short circuit...

I had to go back a few months but it was this years postings. The principle thread was of chips resetting to 03 and I just followed the various side shoots!

Peter A