Where next?

[EddieK]

Please forgive me for going off on a tangent....

My planned layout project is to be set in the first half of the 1970s, portraying British Rail. In those days, locos would display headcodes (where fitted) for the train being hauled. On my layout, I intend to have headcodes on the locos but I also intend to swap locos between trains, so most of the time the headcode displayed will be wrong for the train being hauled.

How about a loco headcode display that can be changed while the loco is on the rails? Preferably the characters will change as if they are on a bling being wound up or down.

Also, I note that my SLW Class 25s will have illuminated speedometers in the cabs - how about speedometers with moving needles...?

 

In the above discussions, the term NFC is used a lot. A few years ago my wife and I stopped at a well known fried chicken "restaurant" near Ellesmere Port for dinner, only to find that they had none of their staple product available for sale at that time. Nowadays, "NFC" means "No F(rude word withheld) Chicken".

[The Johnster]

I reckon working rollerblind headcodes could be done in DCC with existing technology, but it would be fiddly and expensive; the real ones jammed fairly often!  The simplest answer is a compromise, in which the operating session is given 'time out' for displays to be slid into the panels by hand.  Even this would be challenging on locos/multiple units with headcode panels above the cab windows; perhaps a removable clip-on or magnetic headcode box.  But the look of a rolling blind being set by the crew would be wonderful, especially backlit! 

 

The WR hydaulics, except the Hymeks, had rollerblinds operated from outside the loco by means of a square hole drive on the headcode box/boxes.  This could be turned with a carriage key.  It means that the visual aspect of working rollerblinds is compromised on these locos.  On locos with noses, the secondman (or guard acting as secondman) entered the nose through the door in the cab and did the biz, while on locos with flatter cab fronts like 47s or Hymeks you looked down through a sort of periscope on the control desk to see what you were doing.  Cab top headcode boxes IIRC had a drop-down panel in the cab roof: all were operated manually by handle.      

[woodenhead]

@The Johnster You'd simply have LED blinds that can be animated to give the appearance of being rolled if changed.

 

Would be a lot less work than actual working blinds in 4mm scale or larger, for 2mm it wouldn't be impossible to create working blinds but in a space constrained box of DCC goodies an LED would be a much more viable and simple solution.

 

And an LED panel can display domino markers too....

Edited July 24 by woodenhead

[The Johnster]

But could it replicate the appearance of a rollerblind, a cloth material backlit by low-wattage filament bulbs?  RTR's use of leds has hardly been covered in glory, covered in something. certainly, but not  glory; lights way too bright, not diffused, or wrong colour cast are par for the course.  For 1970s headcode panel lighting, the lights should not be visible under the layout's 'daylight' ambient light, nor should cab lights.  An LCD-based display might be more effective, though I realise that this is very much yesterday's technology.  Only the red tail lamps and the white marker lights were discernable in ambient daylight, and you had to make an effort to be certain on bright days.  Same thing with filament coach lighting and oil lamps for semaphore signals and tail lamps.

 

The difficulty of picking out marker lights in daylight is why early pre-headcode box locos carried headcode discs as well as marker lights.  The discs were visible in daylight and the markers at night, but problems arose over the late 50s and the 60s as background lights became more prevalent and covered greater areas as new housing and industrial development ate into green space.  For some reason the WR hydraulics used a single white marker and a red tail light at each end, no discs, but the white markers were only used for low-speed shunting movements.  Similarly, shunting locos had marker lights but no discs.

[billbedford]

On 02/07/2024 at 23:45, Dave John said:

Why would you need to have lower voltage batteries given the ability of modern electronics to build buck/ boost converters of excellent efficiency and small size ? 

 

My last RC loco has 18 V batteries and the electronics has been tested to 27 V. Realistically that could be pushed towards 50 V. Opens up the potential for a lot of energy storage in a small volume. 

 

Because if 5 V is standardised there are lots of cheap peripherals produced for computers. This would be preferable to having to develop components specifically for model railways. 

[billbedford]

On 27/06/2024 at 20:27, The Johnster said:

 Every wheelset on a train powered by an axle motor?

 

Only if someone invents some new physics, electric motors develop their torque at speed and the smaller the motor the higher the speed needed to produce useful torque. That's before you start thinking about how to get all the motors in separate vehicles to run at the same speed. 

[scottystitch]

21 minutes ago, billbedford said:

 

...electric motors develop their torque at speed... 

Do they? (Genuine question) 

 

My understanding is that (DC) motors develop their maximum torque at low rpm due to the back emf in the winding increasing with speed which opposes the supply voltage, reducing the current...

 

It's entirely possible that I am misunderstanding.

 

Best

Scott.

 

EDIT:  

 

https://www.exro.com/industry-insights/torque-and-speed-relationship-the-fundamental-challenge-of-e-mobility#:~:text=As output speed increases%2C the,top speed in less time.

 

https://www.quora.com/Why-do-electric-motors-lose-torque-at-a-high-RPM

 

Edited July 25 by scottystitch

[Dave John]

Good points Bill, but battery voltage becomes more about energy density if you can change the voltage to whatever is needed easily.

 

Axle mounted motors with full torque at low speed?  I have played about with micro stepper motors. Not that difficult to drive and a version with a through shaft would be possible. 

 

They are fairly small and can be made at reasonable cost. 

 

https://www.ebay.co.uk/itm/254604767522?campid=5338947460&mkevt=1&mkcid=1&toolid=10050&customid=&mkrid=710-53481-19255-0&_trkparms=ispr%3D1&amdata=enc%3A1TrAntxqxSceLFYOILw9LlQ29&campid=5338947460&mkevt=1&mkcid=1&toolid=10050&customid=a7b229aff8701b4423fa4f0de0b3de28&mkrid=710-53481-19255-0&msclkid=a7b229aff8701b4423fa4f0de0b3de28

[billbedford]

There are two problems with these motors. They are 2-phase steppers, which while they are OK for actuators, they won't stand up to continuous running for very long. Also, they are cheap because they are over production from other commodities. I'm not sure what the minimum batch size for motors built around 26 x 2 mm pin-point axles would be, but I would think it would last the whole of the UK model railway community a few generations. 

[Dave John]

Well, true as it stands Bill. In the meantime I will continue to mess about with the idea. Not sure that they have issues with continuous running, I have test run for a fair time with no issues. 

 

Generating a 2 phase variable frequency is a bit messy, but look at how much goes into a modern dcc sound decoder. It is well within the capabilities of modern chip design 

 

A long while back I started to use magnets to hold roofs on rolling stock. Kinda pontless a few folk told me.. Look at modern rtr .... 

[billbedford]

I presume you have seen these:

 

http://www.clag.org.uk/axle-hung.html

http://www.clag.org.uk/hickson.html

http://www.clag.org.uk/class31-axlehung.html

[wagonbasher]

58 minutes ago, billbedford said:

I presume you have seen these:

 

http://www.clag.org.uk/axle-hung.html

http://www.clag.org.uk/hickson.html

http://www.clag.org.uk/class31-axlehung.html

Incredible stuff.  I’ll have a go after tea.  
 

Andy

[Dave John]

I have read through most of the clag articles, some very good innovations in there. 

[Bittern]

On 25/07/2024 at 04:11, The Johnster said:

But could [LED blinds] replicate the appearance of a rollerblind, a cloth material backlit by low-wattage filament bulbs? 

E-ink would look better but I haven't managed to find a small enough screen with a remotely decent pixel density (though it's been several months since I last looked). 

 

I have seen pictures of an 0-gauge 195 with a working dot matrix destination display, which looked plausible though I didn't check how accurate it was.

On 28/06/2024 at 05:26, franciswilliamwebb said:

This old chestnut crops up repeatedly.  If there's something beyond "dated" digital then the commercial world's keeping damned quiet about it.  My phone: digital.  My 'pooter: digital.  My TV: digital.  My trainset: digital. DJI drone: digital.

"On-board power supply with NFC contol recharged through the rails": Digital. Command. Control.

DCC is an incredibly primitive protocol, and if it had taken another 10 years or so for a commercially-successful system to appear it would probably have native bidirectional comms (and maybe location awareness) instead of the bodges currently used. Without bidirectional communications DCC is in some ways worse than DC, especially for automation or large layouts (though it also had plenty of advantages even at the beginning). Some of the other flaws, such as only having 2-value accessory commands, have been fixed in updates but aren't widely supported yet. 

 

I think it is unlikely that there would be an incompatible replacement but there's definitely room for improvement, especially since the falling cost of electronic mean that it would be feasible to fit decoders to every vehicle to operate couplings and lights except that would really exacerbate the "which loco is that" problem.

 

In the more distant future, the really cool feature that struck me as a kid seeing the ZTC 511 was that you could use motor feedback to sense the load on a train and, by abusing  CVs for the reverser and brake positions you could simulate steam driving more realistically than the 511 did. 

Edited August 7 by Bittern
clarifying my opinion

[Michael Hodgson]

On 24/07/2024 at 15:36, woodenhead said:

@The Johnster You'd simply have LED blinds that can be animated to give the appearance of being rolled if changed.

 

Would be a lot less work than actual working blinds in 4mm scale or larger, for 2mm it wouldn't be impossible to create working blinds but in a space constrained box of DCC goodies an LED would be a much more viable and simple solution.

 

And an LED panel can display domino markers too....

Yeah, but it wouldn't be as unreliable as a real roller blind!