As a result of the squirrel incident ........

[Martino]

....(see the post in General G Scale) I did some experiments and started some planning. The result is some questions which some kind soul(s) may be able to help with. First though, excuse the rambling but it's helping get my mind clear.

The scenario:

I have an end to end track that runs round the edge of the garden. It's about 250' from one end to the other.

I have a Digitrax DCC set up.

Up till today I have had one power feed located mid way along the 250'. 99% of my rail joints are either split-jaw or Accucraft brass rail joiners, so I virtually never have any power breaks. I've also not experienced any noticeable power loss or drop off. I do have some issues with the sound on locos fading every now and then, but this appears to have nothing to do with the distance from the power feed (as I proved this afternoon).

Anyway, I experimented with attaching the power feed at either end of the track. This seemed to have no effect on the way the locos performed or anything else. It would be easier for me to have the power feed at one end (see later).

QUESTION 1: Am I likely to have power drop off issues by having one power feed at the end of the 250' run? Is there a formula for working this out? Would any voltage drop be significant.

Next issue:

Currently I have a moveable control box that I set up on my patio (near beer, tea etc) which is about midway round the line. I have a radio control transmitter attached to the box. My radio control throttle (admittedly a cheapo Digitrax one) appears to work not perfectly, and only in line of sight. I believe that the newer throttles have better range and aren't worried by line of sight.

My thought is to put all the control gubbins in my garage at one end of the 250'. That's why I'd prefer to have the power feed at that end. Then run a CAT 5 cable round the house, with Digitrax plug in modules at strategic points (suitably weather protected) and maybe three wireless transmitters hooked in also at strategic points and suitably weather proofed.

QUESTION 2: Am I totally Mad? (rhetorical question)



QUESTION 3: Will it work?


Thanks folks, in advance
Track plan is below.

 

[minimans]

Not a DCC man myself but on an analoge 250ft run the voltage drop should be basicaly zero! if you think of the rails as wires they are some pretty stout wires as wires go..... so as you say you have no conectivity problems at the rail joints you should be just fine with a single feed at one end. my upper loop is about 300ft and has just one feed and most of it is aluminium rail.................

 

[Neil Robinson]

QUESTION 1: Am I likely to have power drop off issues by having one power feed at the end of the 250' run? Is there a formula for working this out? Would any voltage drop be significant.

Ohms Law. The voltage drop will be the electrical resistance of the rails multiplied by the current taken from the power supply.
In practise the track resistance depends on the quality of your track joints and you've already addressed this issue. The current varies a fair bit with the type and number of locos and the loads you put behind them.
IMHO a feed at one end should be fine, forget calculations just try it and see. If it works O.K. for a while and then something changes just investigate the cause (probably a rail joint has come loose) fix it and all will be well again.

 

[GrahamMills]

QUESTION 1: Am I likely to have power drop off issues by having one power feed at the end of the 250' run? Is there a formula for working this out? Would any voltage drop be significant.

As the others have written, brass rail is a very thick piece of wire so you should have no problems.

My thought is to put all the control gubbins in my garage at one end of the 250'. That's why I'd prefer to have the power feed at that end. Then run a CAT 5 cable round the house, with Digitrax plug in modules at strategic points (suitably weather protected) and maybe three wireless transmitters hooked in also at strategic points and suitably weather proofed.

Sounds like a great plan. It's what I would do in your position.

QUESTION 2: Am I totally Mad? (rhetorical question)

No more than the rest of us. (I am looking at a wind & rain swept garden as I write this)

QUESTION 3: Will it work?

Should do.

 

[Martino]

Thank you Gents, much obliged.

I see yet another project to add to the list!