A TT120 interpretation of track plan R7277

[Skelton Junction]

Works ok on DC having completed the 3rd loop, will that mean It’s ok for DCC too?

Need a few straights to extend elevated loop fully, hence nothing fixed in place.

Used peco flexi in straight lines only for ease and commensurate with my skill level.

Sidings, engine sheds, Llanberis back scene may move.

[RDS]

The main difference between DC and DCC is that with DCC the whole layout is Live all the time. If you have Points anywhere they will need the Hornby Point clips to ensure that the turnoff from the Point is live all the time as well.

I only use DCC and I have never really used DC but I understand that DCC needs to have cleaner track and picks up on the wheels for your Loco's to work consistently.

[Rallymatt]

It would be wise to bypass the point clips and wire droppers to a powerbus for a robust set up. Particularly where it’s more than a basic oval with a couple of sidings and running multiple locos.

An advantage often claimed for DCC was that the constant 15/16v AC helped keep the rails cleaner, how true that is I don’t know.

[ntpntpntp]

If the layout is properly wired for DC then it'll work on DCC too, there's no magic to it you simply connect all the section feeds to the same DCC track supply and switch on all the isolating sections. Certain trackwork formations such as reverse loops and wyes can take advantage of DCC electronics to change the rail polarity automatically, but again can still be worked in the traditional manner with changeover switches.

Having a DCC constant voltage doesn't keep the trackwork any cleaner but it does help negotiating any spots of high resistance at low speed where DC would only be a few volts. DCC can be more sensitive to dirty track and if anything needs the track to be maintained with better cleanliness than DC, due to dirt causing loss of the DCC signal to the decoder. This is something that the HM7000 bluetooth communication bypasses.

[Rallymatt]

Ha ha thanks Nick, I was somewhat dubious about the DCC cleaner track claim, I think it first surfaced in Zero 1 days.

[BritInVanCA]

From the 1980 catalogue. Open to interpretation

[Rallymatt]

BritInVanCA, thanks, I was sure I had seen it somewhere in the day!

[Skelton Junction]

Do the fishplate droppers have to be powered by the R7337 too or can I run them off the duette like the other wired accessories?

[Fishmanoz]

Definitely the 7337. This must power the entire track layout and not have any other power connected to it. And as per current recommendations, particularly not any DC controller including the Duette.

[Skelton Junction]

Ta Fishy I’ll leave the duette to power the lights etc.

How does one connect an R7337 to something other than the track please?

[Fishmanoz]

Rather than plugging the adaptor cable into a power track/clip, plug it into one side of a “choc block” connector, then run the other side into a power bus pair of heavier wires which you run around your layout under the board and to which you then connect all of your droppers.

[Skelton Junction]

Copy that Fishy, it’s either or, not both, thanks for clarifying.

[Skelton Junction]

Would some kind soul be able to provide an example/link for a connection socket unit for the R7337 (so it can remain as new and un tampered) to power the bus?

[Fishmanoz]

That’s the choc block I mentioned in my last - https://uk.hornby.com/community/forum/p9300-power-connector-plug-wire-352826

[Railbob]

Skelton,

I’m working on the same issue and I’ve decided to buy a 7324 cable and adapt it to fit my bus.

Railbob

[Steve-353799]

I take it that the P9100 UK Transformer that I bought will power my bus just as well?

I'm thinking of running 2 seperate ones, one on each side of my layout will that be ok?

Ta,

Steve

PS some good tips on this thread!

 

[96RAF]

The only limitation is the 9100 limited output of 1 amp. It won’t run many locos but will power an accessory bus nicely.

Tip ref using a choc block as an adapter (for the PSU adapter cable) - if you cannot find one with a suitable pitch to match the 2-pin plug, simply chop the block into a couple of single bits and use them.

[P-Henny]

I'm thinking of running 2 seperate ones, one on each side of my layout will that be ok?

 

 

@Steve353.....

If you are suggesting connecting two power supplies to the same track but at two different locations, then I would advise against it. This powering concept has been discussed before in forum and generally not recommended. Much better to use one higher current P9300 4 Amp PSU rather than two P9100 1 Amp supplies in parallel.

[96RAF]

Agreed about not combining power supplies. Previous discussion had noted that this degrades self protection.

[Steve-353799]

So rather than using 2 seperate power supplies for the 2 seperate bus's say one at the top and one at the bottom. It's best to use just 1 power supply Say 15v 4 amps to power the 2 seperate bus's?

[Skelton Junction]

“Tip ref using a choc block as an adapter (for the PSU adapter cable) - if you cannot find one with a suitable pitch to match the 2-pin plug, simply chop the block into a couple of single bits and use them.”

For this, thank you.

[Fishmanoz]

As I’ve said previously and further clarified by RAF above, the adaptor cable can be used without modification plugging it into choc block. Then you can use further choc block sections for multiple connections to the track, if you wish.

Using two 9100s on a single layout - such an arrangement led to a heated exchange of posts the last time it came up. It is possible but may be limited compared to theory as to total current available in practice being less than 2 Amps. Anyone contemplating this arrangement does so at their own risk.

If I were to use 2 PSUs, I would split my layout in two with IRJs and put one PSU in each section. The sections would need to be arranged such that locos are split evenly between them.

My preferred - use a single 4 Amp PSU.

Edit: I took some time to post this and Paul and Rob have posted similarly in the meantime. And then see from RM below.

PS. Each time this comes up, I’m reminded of a 3rd year Physics lab at Sydney University in 1965. We were doing electrical experiments and one group, deciding a single PSU was not producing enough volts and without reference to the supervisor tried using two in series. The PSUs in question were quite robust transformer and valve/vacuum diode designs mounted on large metal chassis (no switchmode or double insulation designs in those days) so the chassis were connected to mains earth and this was also the -ve side of the output DC volts. Not surprisingly with one of the PSUs now seeing a dead short across its output, the results were spectacular, and loud. But for clarity, this is not the situation with two 9100s as the output DC is not earthed to mains, they are floating.

[Rallymatt]

A single power supply for a layout is always the preferred choice as Rob, Paul and Fishy have also said. Put simply to ensure ideal electrical protection for you locos, 1 PSU of correct amperage and designed to work for a model railway application.

When things go wrong, there are no guarantees multiple PSUs will act simultaneously and cut power at same time, that’s when £100’s of damage can occur.

[Skelton Junction]

[Steve-353799]

Ok so I'll use a single 4 Amp PSU. Transformer. I'll connect the 2-pin lead into the connector block and run both Bus 1 and Bus 2 from the same connection. One positive and one negative. Let's say the red is positive. I've heard the saying black to back so I'll run a dropper from the black bus wire (bus 1) to the back at the top of the oval and red to the lower rail.

But here's the thing the black dropper on bus 2 is at the front lol.

So, have I got this bus thing, correct?

Best,

Steve