Musing on live frog turnout wiring

[dpgibbons]

Just musing here.

 

With a live frog setup, the likelihood of shorts would be greatly reduced if the rail sections adjacent to the frog were never at the opposite polarity.

 

This would require feeds to the point blades and the two rail sections adjacent to the frog on the exit tracks to be switched along with that of the frog, such that the disengaged blade and exit rail feed would always be disconnected rather than at opposite polarity to the frog. That could be accomplished with a double-pole triple-throw switch.

 

I've not seen this done, so am I missing something or is the extra complexity not justified by the benefits?   

[Izzy]

You don’t really want the blades to be of opposite polarity to their adjacent stock rails, shorts would be just as likely there, unless the gaps are ridiculously large, which some can be. But the exit rails after the crossing, yes, this is the prime issue I keep reading about with RTL pointwork - which I haven’t used it must be said in over 50 years!

 

Bob

[Jeremy Cumberland]

What shorts are you thinking of? Are you trying to trail through points set the wrong way? Are you using conventional live frogs or Peco Unifrogs? How are you making the insulated joints?

 

6 hours ago, dpgibbons said:

That could be accomplished with a double-pole triple-throw switch.

Triple pole double throw (3PDT), not double-pole triple-throw. However, if you can't trust the  insulated joint between the open switch blade and the frog then you risk getting a short anyway, as soon as a wheel bridges the gap between the stock rail and the open switch.

[5BarVT]

On 17/07/2023 at 10:01, dpgibbons said:

Just musing here.

 

With a live frog setup, the likelihood of shorts would be greatly reduced if the rail sections adjacent to the frog were never at the opposite polarity.

 

This would require feeds to the point blades and the two rail sections adjacent to the frog on the exit tracks to be switched along with that of the frog, such that the disengaged blade and exit rail feed would always be disconnected rather than at opposite polarity to the frog. That could be accomplished with a double-pole triple-throw switch.

 

I've not seen this done, so am I missing something or is the extra complexity not justified by the benefits?   

Two separate ideas here: point blade polarity and ‘beyond the V’.

Isolating the point blades requires a gap or insulation between each of them and the frog.  Having done that, it seems easier just to bond each blade to its adjacent stock rail rather than to the appropriate ‘beyond the V’ rail.

Isolating ‘beyond the V’ is an interesting idea - the loco just stops rather than shorting out.  Relevant factors are the max length of pick ups on the longest loco/unit (a problem if coach lighting is present?) and length of run on with stay alive.  I suspect that the necessary length of over run may make operation of the layout too constrained if it has to cope with unspecified stock e.g. a club layout.

Paul.

[DCB]

On 17/07/2023 at 10:01, dpgibbons said:

Just musing here.

 

With a live frog setup, the likelihood of shorts would be greatly reduced if the rail sections adjacent to the frog were never at the opposite polarity.

 

This would require feeds to the point blades and the two rail sections adjacent to the frog on the exit tracks to be switched along with that of the frog, such that the disengaged blade and exit rail feed would always be disconnected rather than at opposite polarity to the frog. That could be accomplished with a double-pole triple-throw switch.

 

I've not seen this done, so am I missing something or is the extra complexity not justified by the benefits?   

 

Shorts are usually at the frog where Dead frog points are wired as non isolating for DCC or between the back of the blade and the adjacent rail on Live Frog.  The dead section beyond the frog is a great idea for stopping shorts when approaching a wrongly set point as these  shorts destroy plunger pick ups and don't do loco wiring any favours either  Doesn't need anything more than two SPDT microswitches, one for the frog and one for the rails beyond the frog.

Early 00 points were live frog with the whole frog and point blade assembly pivoted to change the road.

 

 

[Happy Hippo]

In one of his many books, the late Iain Rice advocated a cascade system of wiring.  It was only once the road was set and the appropriate signal had been pulled off that the track could be energized.

 

As someone who uses DCC with stay a live capacitors, I'm afraid a short dead section doesn't really help.

 

Although I now use Cobalt motors and use the built in switch to switch crossing nose polarity, my older system used a microswitch which was connected to the operating rod of the turnout.

 

It's a system that has been in use for at least half a century, and has the advantage that it is simple, easy to install and cheap.

 

Sometimes we try to look for an overly complex solution to a simple problem.

 

 

[Nigelcliffe]

36 minutes ago, Happy Hippo said:

In one of his many books, the late Iain Rice advocated a cascade system of wiring.  It was only once the road was set and the appropriate signal had been pulled off that the track could be energized.

 

It works fine for analogue layouts.   Poor with DCC if locos have lights (they come on/off as signals are pulled).    Awful if you have sound locos on DCC - pull the signals and the loco does its start-up routine,  drop the signals and it dies from lack of power.    

 

Solutions need to reflect the needs of the entire layout. 

[DCB]

On 19/07/2023 at 09:36, Nigelcliffe said:

It works fine for analogue layouts.   Poor with DCC if locos have lights (they come on/off as signals are pulled).    Awful if you have sound locos on DCC - pull the signals and the loco does its start-up routine,  drop the signals and it dies from lack of power.   

Solutions need to reflect the needs of the entire layout. 

You just have to prioritise, and most people don't.  The dead section is a great idea to stop over running of wrongly set points.   If you need to park locos or stock with DCC sound and lights adjacent to wrongly set points it  isn't appropriate.   Running a loco into a wrongly set point is not a good idea, but with with 48VA of some DCC set ups it damages the points, pivots and blade tags unless there is polarity switching and even then my switches are only rated at 1 amp,  Do it a few times and you end up with dead blades as well as dead frogs which is where stay alives and additional pick ups are needed.  I run  12 volt 2 amp 24VA DC on my floor layout.  t which damage my fishplates and point blades.    I don't see the point of DCC point control, I haven;t see anything as sophisticated and user friendly as my route setting Diode Matrix system I use for hidden sidings.  It just works and has done for 30 odd years.     The sound  reference is interesting,  I  have yet to come across a satisfactory sound system,  I think if I can get a two decoder system one for sound and one for traction I might be on to something  for diesels  and if I can  work out how to synchronise the chuff to the wheel speed  (I have not found a system which works yet)  I can set the steam sound up using Musescore,  Mainly using the percussion Pallette  I did a pretty convincing Pannier tank track a while ago.

[Graham108]

On 19/07/2023 at 09:36, Nigelcliffe said:

Poor with DCC if locos have lights (they come on/off as signals are pulled).    

Surely with DCC this concept is irrelevant

[Nigelcliffe]

2 hours ago, Graham108 said:

Surely with DCC this concept is irrelevant

You've misquoted or misunderstood what I wrote...     If you have a DCC loco on some track with its lights on (under DCC instruction), but the track power only appears when the route is set (because it is power-routed through the turnouts), then the lights on the loco will go on/off when the turnouts are changed (because the track power goes on/off).  

 

 

[Nigelcliffe]

3 hours ago, DCB said:

You just have to prioritise, and most people don't.  The dead section is a great idea to stop over running of wrongly set points.   If you need to park locos or stock with DCC sound and lights adjacent to wrongly set points it  isn't appropriate.   Running a loco into a wrongly set point is not a good idea, but with with 48VA of some DCC set ups it damages the points, pivots and blade tags unless there is polarity switching and even then my switches are only rated at 1 amp,  Do it a few times and you end up with dead blades as well as dead frogs which is where stay alives and additional pick ups are needed.  I run  12 volt 2 amp 24VA DC on my floor layout.  t which damage my fishplates and point blades.    I don't see the point of DCC point control, I haven;t see anything as sophisticated and user friendly as my route setting Diode Matrix system I use for hidden sidings.  It just works and has done for 30 odd years.     The sound  reference is interesting,  I  have yet to come across a satisfactory sound system,  I think if I can get a two decoder system one for sound and one for traction I might be on to something  for diesels  and if I can  work out how to synchronise the chuff to the wheel speed  (I have not found a system which works yet)  I can set the steam sound up using Musescore,  Mainly using the percussion Pallette  I did a pretty convincing Pannier tank track a while ago.

 

Various topics arise,  mostly agreement, but come from different perspective. 

 

48VA through track, yes for OO and smaller this is too much, but its what a 3A and above system delivers (5A is nearer 70-80VA).   Solution is district cutout breakers set to lower trip currents, which protects switches, blades, wiring, pickups on locos, etc...   

 

DCC point control,  I agree typing numbers into handsets is not nice.  But there are ways of having button panels or software screens every bit as nice as a diode matrix, and can have the same items duplicated on multiple panels with very little additional effort (which in some cases is very useful).   The issue is really wiring complexity vs. system setup.   A bus-based turnout control system uses fewer long wires from panel to layout, but has effort of learning how to setup the panel devices to work.

Sounds,  decent DCC sound decoders will synchronise wheel chuff.  That many don't is poor setup (or cheap decoders which can't).    But, with "in loco" sounds there is always the limit of the small speaker and small amplifier.   
Under baseboard is a possibility with enough effort put into sound positioning (various systems to do this available), but then wheel-synch becomes the problem.  I'm not aware of anyone selling a device which transmits the wheel sync reliably back from a loco (I'm sure its possible to do, and not difficult, there's just no market for such a device). 

[Graham108]

7 hours ago, Nigelcliffe said:

You've misquoted or misunderstood what I wrote...     If you have a DCC loco on some track with its lights on (under DCC instruction), but the track power only appears when the route is set (because it is power-routed through the turnouts), then the lights on the loco will go on/off when the turnouts are changed (because the track power goes on/off).  

 

 

What you say is entirely correct - no power to the track nothing on a loco would work. But if you operate using DCC why would you have sections of track without power?

[Nigelcliffe]

2 hours ago, Graham108 said:

What you say is entirely correct - no power to the track nothing on a loco would work. But if you operate using DCC why would you have sections of track without power?

 

I was responding to the approach Happy Hippo raised in the thread, pointing out what would happen.