Video Archive         Recent Topics      
YMR logo

You are here:  Your Model Railway Club > Getting You Started. > Electrics - DC > 'Stay Alive' capacitors - Do analogue users need to miss out? To bottom of page
                 

 Moderated by: Spurno  
AuthorPost
Paul Chetter
Full Member
 

Joined: Tue Jun 5th, 2012
Location: Lincoln, United Kingdom
Posts: 172
Status: 
Offline

My photos:
view photos in Gallery
view photos as slides

I'm a DCC user and deploy 'Stay Alive' capacitors sometimes in my models. These can help to keep the model moving if there is a temporary interuption in DCC power or even keep the sound running if a sound decoder is fitted.

I would never promote the substitution of a Stay Alive for good track laying, maintainance  and cleaning, but I find the Belt and Bracers of having an on board rechargable power supply very reasuring, especially when exhibiting.

What do you DC users think about adding capacitors to your models for this purpose?

Best regards,

Paul

Ed
Full Member


Joined: Tue Jan 29th, 2013
Location: West Anglia Main Line, United Kingdom
Posts: 3901
Status: 
Offline

My photos:
view photos in Gallery
view photos as slides

Interesting Paul, but in the smaller scales (e.g. 009, N gauge) there ain't a lot of room to add anything, unless it's a 009 Bachmann Baldwin RTR which already has the space for a decoder built in.


Ed

Sol
A modelling Moderator.


Joined: Mon Nov 28th, 2011
Location: Evanston Gardens, South Aust, Australia
Posts: 4147
Status: 
Offline

My photos:
view photos in Gallery
view photos as slides

Paul, no doubt would help under DC but it would need fancy electronics like a decoder in maintaining power to the motor in the correct direction, cannot just tack an electrolytic capacitor across the motor !

peterm
Full Member
 

Joined: Thu Oct 18th, 2012
Location: Bongaree, Australia
Posts: 316
Status: 
Offline

My photos:
view photos in Gallery
view photos as slides

If I know Paul, he'll have something more than his arm up his sleeve. Watch this space.

BCDR
Moderator


Joined: Sat Oct 19th, 2013
Location: Reston, Virginia USA
Posts: 3531
Status: 
Offline

My photos:
view photos in Gallery
view photos as slides

Hi Paul,

The battery power supply (BPS) control developed by Neil Stanton for radio control dead rail running (the ultimate in dirty track) already does this. Takes 12v in (AC, DC or DCC), charges a LiPo battery, AC/DC/DCC in drops, battery cuts in. 450mAh batteries are about the same size as a decent capacitor. And enough to run an engine for minutes, not seconds. Speed control (voltage versus PWM) and real-time charging with variable input and/or PWM needs to be addressed. With a decoder not an issue of course. 

The major issue with any of this is that the current approach to engine chassis design is a big lump of metal, with no real space for additional electronics. A BPS is about the same size as a standard HO/OO decoder. Tender locomotives or older engines with space are not an issue.

I am not sure if this is addressing a market need or trying to create one, never having had a DC layout. I have the impression from bench testing that the really slow speeds that DCC control has are not there with DC unless it's a really good DC control system. I suspect that if the consensus that keeping track, wheels and pickups clean is followed, add-in electronics to overcome dead spots are usually not necessary. A modern engine with bogie drives or straight gears and fly-wheels will trundle over dead spots anyway. Most of the issues seem to be with small steam locomotives using older gearing systems and poorly designed pickups. Or poorly installed ones.

Nigel




Ed
Full Member


Joined: Tue Jan 29th, 2013
Location: West Anglia Main Line, United Kingdom
Posts: 3901
Status: 
Offline

My photos:
view photos in Gallery
view photos as slides

BCDR wrote: never having had a DC layout


Wot, never had a train set when you was a nipper Nigel?

:mutley


Ed

Paul Chetter
Full Member
 

Joined: Tue Jun 5th, 2012
Location: Lincoln, United Kingdom
Posts: 172
Status: 
Offline

My photos:
view photos in Gallery
view photos as slides

Thanks to Ed and Sol for your responses. I really appreciate that you raised practical and electronic issues rather than dismissing the idea out of hand.

Space can indeed be a problem in many locos, and not just in the smaller gauges. Choosing the optimal components can be useful in overcoming this in some cases.

I've not used tantalum capacitors myself, but Nigel Cliffe has posted many such solutions on 2mm forums, so it is possible with at least some models in smaller gauges.

It's also true that charge/discharge management of the capacitor will be required. I don't know if there is any established good practice for this using a fully analogue pathway.

I do know that most DCC decoders may operate in analogue mode, some are able to 'manage' Stay Alive capacitors though not all can do both concurrently.

Nigel

Apart from the occassional test run, I have not operated an analogue layout (of my own) since 1979 so I'm also unfamiliar with the DC 'scene'. I have, however, attended many exhibitions and witnessed the 'Hand of God' helping along some poorly performing models, analogue and digital. So I wondered if similar solutions could be applied in each case.

Most of my experience is with DCC so naturally my ideas are initiated in DCC solutions.

It seems to me that whilst radio control and rechargeable battery power certainly have merits, the physical size and or design of our models means that smaller scales are less well catered for.

I know a few analogue modellers who have fitted decoders purely for their ability to operate Stay Alive capacitors in analogue mode whilst still retaining full control of their models.

The purpose of this post is to gauge if there is a need or not and to shine a light on the possible alternative solutions.

You raise an interesting point about slow speed control on analogue v digital. If the battery powered models are running in analogue, then does that result in quality of slow speed running more, less or equal to that though the rails. If to get the best requires digital control, then that will require a decoder as well as the radio receiver, needing even more space overall.

Decoders are available with sound on board which, for some, will add to their functionality without a large trade off in terms of additional space. I don't know how this is managed in a radio controlled set up, so I can't compare, though of course any solution will require a speaker.

Best regards,

Paul


BCDR
Moderator


Joined: Sat Oct 19th, 2013
Location: Reston, Virginia USA
Posts: 3531
Status: 
Offline

My photos:
view photos in Gallery
view photos as slides

Hi Paul,

Neil Stanton has already commercialized a battery control unit that works with DC, functions as a LiPo battery charger and switches from track to battery when the rails are dead. In other words it is feasible. The switch needs to be able to remember the voltage (or pulse width) so that the motor goes at the same speed when the track goes dead. The switch needs to be wired into the decoder with DCC. Straight to the motor with DC.

Small LiPo batteries are not much bigger than a sugar cube speaker. The switcher is about the size of a decoder. No need for radio control with DC if you can get the memory in the switch.

Yes, this is aimed at the dead rail folks, but the principle is there.

Ed: Yes, about 10 years old. Christmas present.  I got to play with it in March after my dad and uncle got tired of it. Two speeds, off and full speed. Probably skidded across dead sections, carpet fibers, cat hairs, missing track. 

LiPos and capacitors are chalk and cheese when it comes to current density. The ones I use are 1Ah. At 0.5A draw that is a lot of dead track. Or dead frogs.

Nigel

Paul Chetter
Full Member
 

Joined: Tue Jun 5th, 2012
Location: Lincoln, United Kingdom
Posts: 172
Status: 
Offline

My photos:
view photos in Gallery
view photos as slides

Hi Nigel,

It looks as if the system you describe requires a separate controller for each loco, a receiver, a switch module, a decoder and a LiPo battery.

The downsides I see immediately are:

1.Cost. Starter pack including a Tsunami sound decoder $299 plus speaker at $13 plus Battery pack at $59. That's $371 in hardware for each loco.

2. How do you get all that kit, including a speaker if using a sound decoder, into a Hornby R&H48DS?


Best regards,

Paul

BCDR
Moderator


Joined: Sat Oct 19th, 2013
Location: Reston, Virginia USA
Posts: 3531
Status: 
Offline

My photos:
view photos in Gallery
view photos as slides

Hi Paul,

Note I didn't recommend it  The concept is a battery switch unit, battery and rail current.  In this case DC. Where Neil has gone is radio control, DCC decoder, switch, battery power, dead rail.

The switch also controls the uniform charging of the battery cells.

I stuffed the DCC system into the tender if a Collett Goods using a full size speaker, and also into the innards of a MainlineWarship, which is mostly empty  space.

Nigel

Paul Chetter
Full Member
 

Joined: Tue Jun 5th, 2012
Location: Lincoln, United Kingdom
Posts: 172
Status: 
Offline

My photos:
view photos in Gallery
view photos as slides

That's illuminating, thank you, but how would that work in a Hornby 00 gauge R&H 48DS?

This model has a body length of just 45mm.

Best regards,

Paul

BCDR
Moderator


Joined: Sat Oct 19th, 2013
Location: Reston, Virginia USA
Posts: 3531
Status: 
Offline

My photos:
view photos in Gallery
view photos as slides

Hi Paul, 

It won't. It goes on the flat car it tows around. Same as it won't go in most OO narrow gauge, N scale and a lot of small OO engines. Up to the electronic design people to come up with smaller units that do fit. And that applies to DC.

So.....?

Nigel


Paul Chetter
Full Member
 

Joined: Tue Jun 5th, 2012
Location: Lincoln, United Kingdom
Posts: 172
Status: 
Offline

My photos:
view photos in Gallery
view photos as slides

So.....?

Sometimes a solution, like a decoder equipped model with a Stay Alive connected using DC power, is already available.

I am interested in whether DC users feel that there is a need for it.

Best regards,

Paul

Ed
Full Member


Joined: Tue Jan 29th, 2013
Location: West Anglia Main Line, United Kingdom
Posts: 3901
Status: 
Offline

My photos:
view photos in Gallery
view photos as slides

I think it would be useful for DC, as long as it was small enough and not too expensive.

Electronics has moved on a lot, there are some people putting RC in 006.5 scale locos, so capacitors even for N gauge should be possible.


Ed


                 

Recent Topics Back to top of page

Powered by UltraBB 1.15 Copyright © 2007-2011 by Jim Hale and Data 1 Systems. Page design copyright © 2008-2013 Martin Wynne. Photo gallery copyright © 2009 David Williams.