melmerby

3 hours ago, WIMorrison said:

On the contrary, it is very relevant.

 

If the OP (or anyone else) doesn't have enough power connections from the bus to the track and is relying on rail joiners then that is a route to problems, and those problems can be overcome by soldering the rail joiners to the rail. I use this technique regularly and it is very effective.

But not recommended if you get large variations in temperature.

I found out the hard way when I had not allowed enough expansion gap and when it hit 35C the track buckled.

If you solder you have no expansion room at all.

On 14/03/2024 at 18:12, Michael Hodgson said:

I used to live in South Birmingham and belonged to the local MRC which met once a week in Hazelwell station on the Camp Hill line.  However that was 50 years ago, and they had no end of trouble with vandalism.  If the club is still going they will no doubt have moved by now,

Hazelwell station became a bathroom showroom a while ago and was demolished a couple of years back, it is now the site of the new Pineapple Road station on the Camp Hill line.

5 minutes ago, Holby Railway said:

how do i do that please, im trying but cannot find a way to change it ?

Go back to your original post and click EDIT, you can then edit the title (but only when editing the first post)

20 minutes ago, Mol_PMB said:

It's the future: net zero railtours. A load of colourful diesels on the front doing nothing more than provide highly-amplified DCC sound effects, and an electric loco subtly pushing from the back.

I thought they were using a pack of rechargable AA cells to provide the traction current😄

5 hours ago, 009 micro modeller said:

The issue of the wheel profiles being incompatible also doesn’t seem to apply globally - e.g. as covered elsewhere on RMWeb there are some trolley/interurban museums in the US that also operate some very heavy electric railway locomotives, all DC overhead obviously but sometimes running off a lower voltage than the one they were designed for (a bit like if Crich operated an EM1, which obviously they don’t/can’t).

There are countries where street running trams go onto proper railway tracks (ignoring Supertram) with the platforms having a low section for the tram stop

5 hours ago, pH said:

According to Wiki, Dunfermline trams ran on 3ft 6in track:

My ancient brain not recalling the correct info!

26 minutes ago, Andymsa said:

the room is temp controlled with air conditioning.

Lucky You🙂

Mine varies between 0 & 35 Celcius

On 29/04/2024 at 10:41, Nile said:

It's also worth keeping an eye on their second channel, That's TV 2 (Fv65). This week it looks like they are showing films on Irish railways at 5am.

On 30/04/2024 at 17:15, montyburns56 said:

 

I've tried to record two of them and in both cases my PVR has said that the episodes were not actually broadcast, so I'm wondering if it's a mistake on the EPG or something else.

On 30/04/2024 at 18:16, Nile said:

I've also failed to record them. It could be an error, or it could be the channel isn't on-air on freeview at that time (like their main channel).

Either way I hope they get repeated at a more watchable time.

It could be the channel not putting the required or correct info into the data stream.

The "budget" channels are notorious for get things wrong.

6 minutes ago, Derekl said:

 

It looks to me that you have feeds for each full length of track in the fiddle yard, but not for each track section. You need feeds on each individual piece of track, so that you are not relying on rail joiners for continuity. You should also be feeding point frogs through the motor switch, which isn't apparent from this diagram (but may simply not appear).

I would agree with that, rail joiners are a problem waiting to happen. They don't always cause problems but eliminating the possibility is good practice.

Providing feeds whilst building a layout saves a lot of work later, if they are needed.

Dont forget that a tram wheel is not as thick as a heavy rail wheel.

The heavy rail wheel is meant to run on the coned part of the wheel on straight track as well, the flanges ideally not touching the rail,  whilst the tram wheel always is held by the flangeway on street track.

These days modern trams and railway wheels seem to use the same track profile

Sheffield Supertram Tram/Trains run on both street track & railway track.

(I think Dunfermline(?) also have 4' 7 ¾" gauge)

On 04/05/2024 at 08:51, RAF96 said:

 

 

@melmerby do you have a link file for use with your USB scope to translate the binary commands into text. I wrote one initially but never got it finished.

Apologies for the fuzzy screen grab.

 

 

Sorry. No I don't

The odd occasion when I've had the scope on the layout I was just looking for a good signal that the Picoscope would resolve properly.

The main concern was ringing (following comments elsewhere on RMWeb) which "Bus Terminators" are supposed to cure, but I didn't get any on my 20' x12' layout with 100s of feet of track and numerous sidings.

The only thing I found was that a Digikeijs DR5000 had a less clean waveform than either a Lenz 100 system or a Roco Z21

58 minutes ago, GrumpyPenguin said:

This discussion is a perfect example of "a little knowledge can be dangerous".

That comment is a perfect example of arrogance,

"I'm a professional and I know best"☹️

On 03/05/2024 at 19:30, Steamport Southport said:

And why do they always ask for Guinness at the end?!  😡

Its to prove that somebody actually drinks the stuff!😄

18 minutes ago, 88D said:

How many of these retained their wartime non-window cab? Is there a directory of numbers?

I've looked in RCTS and including the later updates "one at least - 2239" was still unfitted at the time of publication in 1956.

Need someone with a book on the 2251s

Anyone spotted the bees at Crowcombe Heathfield?

Buzzing all around the camera.

2 hours ago, Crosland said:

Cable sold for mains wiring has a current rating, but it's rated such that the voltage drop will be within allowable limits for mains

It also is dependent on installation.

e.g. open wiring, clipped to wall, buried in plaster, bunched in conduit etc. All are different ratings for the same cable.

I'm bemused by all the talk of even minimal voltage drops needing to be eliminated for a booster to work correctly and cut the power on an overload

Every piece of track on my layout is feed through 2 diodes* which drop the voltage in the range 1.2 - 1.4 volts, yet the booster cuts on the slightest hint of a short circuit, it is set to 4.5A trip and is fed from a 110W DC power supply.

* for occupancy detection.

49 minutes ago, Crosland said:

Current ratings are meaningless unless you know the voltage drop per unit length at a given current.

So 60 ohms per km and current rating at a given temperature isn't a good enough description?

All I could find was this (from BRM):

https://www.everand.com/article/724910357/The-W-R-Re-Signalling-Scheme-Concrete-Train

1 hour ago, GrumpyPenguin said:

As an electrical engineer I would never attempt to fault find using a dead short, not good electrical practice.

But you are not a DCC engineer.

1 hour ago, RFS said:

 

Suggest you have a read of this article to get a better understanding of the purpose of doing the coin test for DCC systems.

IIRC Digitrax actually recommend this.

The McKinley Railway used this as it was being built to verify the wiring.

10 hours ago, corneliuslundie said:

Here is a view which makes most of us seem very moderate in our views:

https://countrysquire.co.uk/2019/10/26/end-hs2-the-countryside-vandal/

It came up in a discussion on graffiti on GWR 800 class units. which includes several times the letters CSV

Jonathan

I notice it's 5 years old.

It also rolls out the same old discredited twaddle, especially the

Quote

HS2 is a nature-destroying, cash-burning monument to a bygone age of transport.

I suppose the twit that wrote that goes everywhere in a "modern technology" gas guzzling Range Rover.

2 hours ago, jamesed said:

DCC is a complex signal running at a much higher frequency than normal ac power.

It's just a square wave with a varying duty cycle, hardly complex.

This is mine using a 'scope with DCC capability

It's also very low in the frequency range (app 8kHz) where the effects of Inductance and capacitance do not have a huge effect

The biggest effect is resistance which will affect the speed of the loco if the voltage is dropping by any measurable amount

13/0.2 typically has a resistance of about 60 ohms per kilometer, that's 60 milli ohms per meter.

22 minutes ago, jamesed said:

32/0.2mm wire is what we in Europe know as 1mm sq. and that is very small for using as bus wiring

Europe includes the UK where 32/0.2 & 1mm are both used to describe the cable

The RS Pro cable has 17A rating, several other brands show 10A or more

Most DCC suppliers sell it for bus wiring and IMHO 10A is perfectly adequate.

What's the point of buffers if you don't use them occasionally?😄

1 hour ago, KeithMacdonald said:

 

Do tell, what would you consider to be credible sources that do not attract cynical scorn?

Don't do funnies then?

I assumed it was a bit of self deprecation.