Date   

Re: component electrical specifications?

Robert Hughes
 

Blair. I am considering a drop down bridge across a door way to access more room for future expansion of my lay out. It would be of great interest to me to see what, how you have built yours. I have seen several posted in different groups and YouTube, but most are not conclusive on how to do the gate and to power it in it's dropped position. This blog is interesting to me, but I am afraid I need more detail (pictures). 
Thanks in advance for your response.

Robert 

On Thursday, August 19, 2021, 09:24:40 AM CDT, Blair <smithbr@...> wrote:


To me, it's of little use to de-energize the bridge track itself, as if
you actually drop the bridge when a train is on it, "you ain't paying
much attention!".  YMMV, though, as perhaps your bridge is remotely
operated, where the person causing the opening isn't standing at the
bridge waiting to go through the opening?

Blair

On 2021-08-19 9:58, Dave Emery via groups.io wrote:
> What I want is for both the track on the drop-gate itself and the leads in either direction to be controlled by the position of the drop-gate. (i.e. when the gate is down, the leads have no power.) To do that, it seems I will need two switches, one on either end, or use a contact switch (e.g. a ‘pogo peg’) that passes power across the closed gate’s gap.
>
>     dave
>
>
>
>
>
>






Re: component electrical specifications?

 

I would use a 1 Ampere "Microswitch" or sometimes called a lever or roller switch.  Note that a magnetic reed switch is not a "Microswitch".   This rating will only be exceeded under a rare condition where there is a short circuit and the lift gate switch activates at precisely the same moment as the short.  All DCC systems will remove power milliseconds after the short occurs.

If you use a higher rated switch the contact material will be silver or similar metal and constitutes what is called a wet contact.  The reliability of this contact depends on enough current being present to wet or partially melt the contact material on making the contact.   Most of the time you will have little or no current flowing when the contact is made.  A high current contact will fail over time by oxidizing the surfaces.  There are exceptions but in general you want a gold or dry contact and gold contacts are rarely rated for more than 1 Ampere.  Exceptions are switches that are designed to rub off oxidization each time they are made, or combination contacts that are silver with a gold over plating.  Combination contacts will remain dry contacts  if the current is always low.  In a high current situation the gold layer of the combination contact is burnt by the current leaving a silver contact.

There are a lot of engineers out there that do not know this information.  It is rarely taught in school and in my case was learned in the field.

Best Regards,
Ken Harstine


Re: magnet wire

 

34 AWG magnet wire is rated for 300mA and therefore should be usable for most applications in a locomotive.

I recently discovered TEMCO brand magnet wire.  They have an insulator that is designed to be removed by soldering.

34 AWG Copper Magnet Wire MW0085 - 2 oz Magnetic Coil Red Soderon 155

The price is reasonable, and shipping is free.

Best,
Ken Harstine
Holyoke, mA


Re: DCC Bus reversing question

Blair
 

I am about to leave for 2 days; I have become aware that postings are appearing here on groups.io that I am not seeing on email; not sure why, as since some are coming through, it shouldn't be a spam filter.  Since I cannot log onto groups.io for the next two days, I will cease responding until I return to this forum, in order to not add a layer of confusion by not responding to posts I'm actually not seeing.
Thanks, everyone, for hanging in with me as I work through this.
Blair


Re: DCC Bus reversing question

Blair
 

See below

On 2021-08-19 10:06, Jim Betz wrote:
Blair,
  I understand more now (fully?).  Since you are committed to this track plan
here is what I suggest as a "solution that will make things possible/easy
enough that it works".
  Figure out a way that you isolate the 4 foot section with the double
cross-over so that - it is strictly "one train at a time" whenever any
train is crossing over.

How so?  When the four turnouts are aligned such that there are two
|| running tracks, there is no electrical problem whatsoever.  Agreed, when
the turnouts are set "X", two trains can't progress at the same time.  That's
just a physics thing; two objects cannot occupy the same space.

If you have a second train entering that 4' section
while another train is crossing over you are going to have a short that
will be unresolvable ... without dragging one or both trains forward or
backward by hand.

Don't see your point; however, I did not indicate each and every electrical
gap on that drawing - I can do so, if you think it will change your concerns.
The passing siding and main are still powered, and
nothing prevents trains from running on them.  As for the turnouts and
crossing, I will assemble it again and power it, but I've checked this all
out electrically previously.

  My solution would be to make the approach tracks on the "other routes"
(other than the acitve cross-over route) completely DEAD for at least as
long a distance as an ABBA set of your longest locomotive - even if you
don't ever intend (now) to run such an ABBA set.  Don't forget that an

ABBA set, with keep alives, can run all the way until the last locomotive
is in the dead track before it stops.  I would wire it up/control it so that
the act of throwing either cross-over route kills the approaches on the
other route.
There are only two settings, as I've repeatedly set.  All turnouts set for X,
or all turnouts set for ||.  As such, in one setting, the depicted section
resembles a big 'O', and in the other setting it resembles a big '8'.

Perhaps I'm just thick, but I'm not seeing your concerns.  Please explain
the added complexity of the crossover that I'm not seeing.

                                                                                            - Jim


Re: component electrical specifications?

Blair
 

To me, it's of little use to de-energize the bridge track itself, as if you actually drop the bridge when a train is on it, "you ain't paying much attention!".  YMMV, though, as perhaps your bridge is remotely operated, where the person causing the opening isn't standing at the bridge waiting to go through the opening?

Blair

On 2021-08-19 9:58, Dave Emery via groups.io wrote:
What I want is for both the track on the drop-gate itself and the leads in either direction to be controlled by the position of the drop-gate. (i.e. when the gate is down, the leads have no power.) To do that, it seems I will need two switches, one on either end, or use a contact switch (e.g. a ‘pogo peg’) that passes power across the closed gate’s gap.

dave





Re: component electrical specifications?

Blair
 

Dave

That's up to you.  I'd rather use contacts in the bridge area to simply energize relay(s) that are placed where it is best to interrupt the DCC bus.  But, as usual, Rule number 1 applies - it's your railroad!

Blair

On 2021-08-19 9:58, Dave Emery via groups.io wrote:
What I want is for both the track on the drop-gate itself and the leads in either direction to be controlled by the position of the drop-gate. (i.e. when the gate is down, the leads have no power.) To do that, it seems I will need two switches, one on either end, or use a contact switch (e.g. a ‘pogo peg’) that passes power across the closed gate’s gap.

dave





Re: DCC Bus reversing question

Jim Betz
 

Blair,
  I understand more now (fully?).  Since you are committed to this track plan
here is what I suggest as a "solution that will make things possible/easy
enough that it works".
  Figure out a way that you isolate the 4 foot section with the double
cross-over so that - it is strictly "one train at a time" whenever any
train is crossing over.  If you have a second train entering that 4' section
while another train is crossing over you are going to have a short that
will be unresolvable ... without dragging one or both trains forward or
backward by hand.  
  My solution would be to make the approach tracks on the "other routes"
(other than the acitve cross-over route) completely DEAD for at least as
long a distance as an ABBA set of your longest locomotive - even if you
don't ever intend (now) to run such an ABBA set.  Don't forget that an
ABBA set, with keep alives, can run all the way until the last locomotive
is in the dead track before it stops.  I would wire it up/control it so that
the act of throwing either cross-over route kills the approaches on the
other route.
                                                                                            - Jim


Re: component electrical specifications?

Dave Emery
 

What I want is for both the track on the drop-gate itself and the leads in either direction to be controlled by the position of the drop-gate. (i.e. when the gate is down, the leads have no power.) To do that, it seems I will need two switches, one on either end, or use a contact switch (e.g. a ‘pogo peg’) that passes power across the closed gate’s gap.

dave


Re: component electrical specifications?

Blair
 

Swanny, it sounds like all you've done is depowered the track on the bridge - but I hope that's just a misreading.  What should be done is removing power from the approaches to the bridge, which can get very complicated in the case of multiple routes approaching the bridge.
Blair


Re: component electrical specifications?

Blair
 

I suspect over-currenting the alarm switch will only result in it's premature failure, not a fire or other calamity.  In a protective situation like this, switch failure is fail-safe.  Still, it might be better if the alarm switch simply dropped power to a SPST cutout relay.  Or, as the OP asked, use a switch capable of dropping the DCC bus by itself.
Part of this discussion should revolve around topology - you want to drop the DCC power for 'some distance' either side of the bridge, to prevent running into the abyss, but also to prevent backing into the abyss.  So it's not about dropping power to a 12" section of rail, but rather a significant length of power bus.  As such, it may be more convenient to locate relays on opposite sides of the bridge to drop their respective sections of bus.  IF that's the case, then use the alarm switch to drop the control voltage to those relays, thereby reducing it's current requirements as well as increasing your protection.
No one can tell you the right approach without more information than has been given.
  
By the way, I do this on my 'guillotine' wall gate, which has tracks on both sides, and rises 24" to make life easier when working, not running trains - if the gate is down in position, it powers a relay that allows DCC power to that whole section of the layout; if the gate is lifted, that whole section of the layout dies.  Since the gate never opens in regular operation, that works for me.  My lower level drops and liftouts (4 of them) will need to be more "subtle", as one or more may need to move during operation (as I get older and less limber), but for now, all-or-nothing is acceptable, as only the upper level is constructed and operable.
Blair


Re: DCC Bus reversing question

Blair
 

Steve

Interspersed comments below.

Regards

Blair

On 2021-08-18 23:14, Steve Haas wrote:

"In the photos area, under my name, as we now can't load JPG files to the files area."

Blair,

I've downloaded and reviewed your JPG.

In my opinion you're making this more complex than it needs to be.
Believe me, I wish it were so.  Read on.
I'll get to that, but first answer a couple of questions:

1) These are the only paths that a train uses to reverse - Yes/No?
Yes, as far as trains on this portion of the layout.
2) How much of this trackage has already been built?
Almost all, the area around the crossover will go in last, probably at the end of the month.
3) How much of this trackage that has been built has already been wired?
In progress; yard wired, sidings mostly so
Back to the track plan:

1) If you remove (for discussion purposes) the double crossover at "Y", all you have are three loops around the layout, never needing to reverse electrical phasing:
A) Loop "C',
B) Loop "C-B-A-B-C", and
C) Loop "C-B-A-D-C".

Wire "Rail A" to the outer rail & "Rail "B" to the inner rail (or vice versa) and you are done with this stage of electrical design - no reversing sections, just straight DCS> Booster>PSX and PSX-AR in parallel (not series) as you have currently noted in the Jpg.
Sure, I get all that, but not where I'm going.
2) Now let's reintroduce that double cross-over - this creates the possibility to reverse trains:

A) Is this track already laid? If not, there's no physical rework needed - just rethinking and re-drawing the wiring specs . . .
Already committed, not laid, see notes below near end.
B) What is the wiring architecture of the crossover? Are the two paths totally isolated electrically from each other? If they are it eliminates a potentially thorny problem. If not, might need a Tam Valley Frog Juicer to manage the four points in the diamond.
Aware of the issues I may face here, but thanks.  The crossover is 4 turnouts and a diamond, all in PECO Insulfrog C100.  As such, I have near-total flexibility for the wiring presuming I put in enough insulated joiners.  As Insulfrog, I don't have any frogs to worry about, per se.
C) Now let's address where to place the reversing sections themselves: Knowing only what you've shared with us and the fact that this a logical and not necessarily a scale drawing of the layout, I'd suggest the following:
i) Two reversing sections:
` a) the first is in the upper right quadrant of loop "A", starting one train length before the upper left turnout in the crossover, and extending to the gaps in all four rails to the right of that turnout,
b) the second is in the lower right quadrant of loop "A", starting one train length before the lower left turnout in the crossover, and extending to the gaps in all four rails to the right of _that_ turnout.
No, that won't work.  Loop A does more than just a pass around the layout.  It interchanges with another RR (the ACR, the real focus of this monster).  If I made your (a) section reversing, I would be making a mainline-and-passing track-and division point yard(location called White River) all reversing; trains could be entering the passing track at one end while another enters the mainline track at the other, which violates Rule 1.  Similarly with (b), the main and siding at Franz may be entered and exited simultaneously.

ii) One reversing section:
a) If you are not wedded to the double crossover, and the straight section in the middle of the diagram is physically long enough, consider replacing the double crossover with two single crossovers at least a train length apart. There are folks involved in layout design that suggest this increases operating flexibility - I'm not in a position to comment on that, perhaps others will chime in. If you're interested in this approach, let me know and I can help with location of the single reversing section needed to do things that way.
Yes, that would work, but is not physically possible in this design.  I have about 4' where those two tracks are parallel and together; it's either the crossover depicted, or nothing.
Note that all variations of what I've suggested eliminates the need to have reversers of any type be in series with PSX units. This is important, because as others have said, A PSX-AR is just another PSX with an AR unit added in - they are not designed to be used in sequence.
N.B. This design originated with the following assumptions.  1) the reversing of the whole yard would be done with a 10A DPDT relay driven synchronously with the Tortoises of the crossover. 2) the yard, approaches, and X trackage would be handled by four sections of a PM42 downstream of the reversing relay.  As I saw it, then and now, the design will work.  At this point, I'm only trying to accommodate the needs of an increasing number of sound units, both in terms of increased current draw, and in terms of 'loss of fidelity' when something happens(momentary shorts, and of course the act of reversing) and the locos all reset.  The latter is partly addressed by turning off tracks that are not routed to - at a maximum, only two tracks in the yard need to be powered at any one time.  Also, if a passing track is isolated by the turnouts at both ends being set against the train, there is no need for that track to be powered.  But I would prefer electronic protection and reversing, if I can accomplish it.  Track D, by the way, allows me to also use this staging yard as a temporary end point for the ACR, as we slowly build out the double deck 600' mainline.  Without it, I'd need another portable yard to allow me to run trains while the lower half of the layout gets built. Similarly, track D on the second staging level allows temporary termination of the north end of the ACR.  Both of these options are very important at this time, but will likely be removed in the final version of the layout.

Discussion of physical reality.  Loop D runs around the walls of a 10x28 room.  The tracks from N to L runs CCW around the room, rising at 2%; similarly, the track from S to Q runs CW around the room, rising at 2%; point Y actually exists 8" 'above' the Letter D, if we were to try to relate this diagram to reality.  I guess I'll upload an actual track diagram sometime this AM, though it's likely to drag the conversation away from the focus - reversing.

Blair

Give a holler if you would like to discuss further!

Best regards,

Steve

Steve Haas
Snoqualmie, WA







Re: DCC Bus reversing question

Steve Haas
 

"In the photos area, under my name, as we now can't load JPG files to the files area."

Blair,

I've downloaded and reviewed your JPG.

In my opinion you're making this more complex than it needs to be.

I'll get to that, but first answer a couple of questions:

1) These are the only paths that a train uses to reverse - Yes/No?
2) How much of this trackage has already been built?
3) How much of this trackage that has been built has already been wired?

Back to the track plan:

1) If you remove (for discussion purposes) the double crossover at "Y", all you have are three loops around the layout, never needing to reverse electrical phasing:
A) Loop "C',
B) Loop "C-B-A-B-C", and
C) Loop "C-B-A-D-C".

Wire "Rail A" to the outer rail & "Rail "B" to the inner rail (or vice versa) and you are done with this stage of electrical design - no reversing sections, just straight DCS> Booster>PSX and PSX-AR in parallel (not series) as you have currently noted in the Jpg.

2) Now let's reintroduce that double cross-over - this creates the possibility to reverse trains:

A) Is this track already laid? If not, there's no physical rework needed - just rethinking and re-drawing the wiring specs . . .
B) What is the wiring architecture of the crossover? Are the two paths totally isolated electrically from each other? If they are it eliminates a potentially thorny problem. If not, might need a Tam Valley Frog Juicer to manage the four points in the diamond.
C) Now let's address where to place the reversing sections themselves: Knowing only what you've shared with us and the fact that this a logical and not necessarily a scale drawing of the layout, I'd suggest the following:
i) Two reversing sections:
` a) the first is in the upper right quadrant of loop "A", starting one train length before the upper left turnout in the crossover, and extending to the gaps in all four rails to the right of that turnout,
b) the second is in the lower right quadrant of loop "A", starting one train length before the lower left turnout in the crossover, and extending to the gaps in all four rails to the right of _that_ turnout.
ii) One reversing section:
a) If you are not wedded to the double crossover, and the straight section in the middle of the diagram is physically long enough, consider replacing the double crossover with two single crossovers at least a train length apart. There are folks involved in layout design that suggest this increases operating flexibility - I'm not in a position to comment on that, perhaps others will chime in. If you're interested in this approach, let me know and I can help with location of the single reversing section needed to do things that way.

Note that all variations of what I've suggested eliminates the need to have reversers of any type be in series with PSX units. This is important, because as others have said, A PSX-AR is just another PSX with an AR unit added in - they are not designed to be used in sequence.

Give a holler if you would like to discuss further!

Best regards,

Steve

Steve Haas
Snoqualmie, WA


Re: component electrical specifications?

Robin Becker
 

John,

That reed switch is rated for only 300 mA @ 30 V.  If you have multiple locos, sound loco, etc or a short circuit you might have problems especially if it ever switches while under load?

Robin


Re: component electrical specifications?

Swanny
 

Robin, I have a "lift" gate that I protect with magnetic reed switches, such as used in alarm systems.  You can easily find them by searching for the item below on Amazon.  I use one on each end, running the rail feeder (drop) through the switch, which is closed when the gate, or bridge, is down.  
John

7939WG-WH - Ademco Surface Mount Contacts


Re: Photo Loop Schematic e.jpg uploaded #photo-notice

Blair
 

Nope, you've completely missed it, Jim.  I want to reverse the entire staging area and it's approach tracks, including the passing sidings.  All as a unit.  Based on the position of one set of switches, which the operators set as a single action.

But, given it's size, I want CB protection of the yard to be separate from the approach and siding trackage. 

I'm not sure what I can say to 'turn your head upside down', as this is what I've been saying all along.

Respectfully,

Blair

On 2021-08-18 20:49, Jim Betz wrote:
Blair,
  Your track plan is very "complex" and your "reversing sections" are (if I understand
how you intend them to work) -very- short (as in just the cross-over area?).  That 
seems, to me, to be a design for "impossible".  You -may- be able to redefine how
you wire it in order to avoid the reversing section nemesis ... a reversing section
that is shorter than the longest train going thru it.  If the train is too long sooner or
later (and usually sooner) the wheels will be crossing the gaps on both ends of
the reversing section.  
  You also added in a statement about "up to 4 trains all moving at once" - which 
further increases the probability (inevitability) that you will have the gaps at both
ends of the reversing section closed (gapped by the wheels).

  I'm afraid the above is the best I can do on this one.  I.e. Warnings, warnings,
warnings.  Running one train at a time it probably works but this seems like a
"double reversing section that is also overlapping another reversing section".

  Here is what I recommend - do what you think works then TEST.  Test first
with only one train, then add additional trains until you "max out".  If you
don't have problems then great.

  One last thing to consider ... are you creating something that "only works if
the operator(s) do all the right stuff at just the right times"?  If you track plan
-and- wiring depends upon humans never making a mistake - you will have
problems.  Not only with boomers - but even with your regular crew and/or
family and/or just you.
                                                                                          - Jim 


Re: Photo Loop Schematic e.jpg uploaded #photo-notice

Jim Betz
 

Blair,
  Your track plan is very "complex" and your "reversing sections" are (if I understand
how you intend them to work) -very- short (as in just the cross-over area?).  That 
seems, to me, to be a design for "impossible".  You -may- be able to redefine how
you wire it in order to avoid the reversing section nemesis ... a reversing section
that is shorter than the longest train going thru it.  If the train is too long sooner or
later (and usually sooner) the wheels will be crossing the gaps on both ends of
the reversing section.  
  You also added in a statement about "up to 4 trains all moving at once" - which 
further increases the probability (inevitability) that you will have the gaps at both
ends of the reversing section closed (gapped by the wheels).

  I'm afraid the above is the best I can do on this one.  I.e. Warnings, warnings,
warnings.  Running one train at a time it probably works but this seems like a
"double reversing section that is also overlapping another reversing section".

  Here is what I recommend - do what you think works then TEST.  Test first
with only one train, then add additional trains until you "max out".  If you
don't have problems then great.

  One last thing to consider ... are you creating something that "only works if
the operator(s) do all the right stuff at just the right times"?  If you track plan
-and- wiring depends upon humans never making a mistake - you will have
problems.  Not only with boomers - but even with your regular crew and/or
family and/or just you.
                                                                                          - Jim 


Re: Block Detection for signalling and automation

Don Vollrath
 

The easy way for signaling is to make the turnout and points part of the mainline signal block leading up to it. Both of the tracks leading away from the frog should be isolated and start the next signal blocks. If one of them is a siding it does not need to be separately sensed. Your signaling logic may want to include the turnout position.

DonV


Re: component electrical specifications?

Robin Becker
 

Voltage depends on your scale, i
I believe it can be up to 27 Volts or so for larger scales per the DCC specs.   Current depends on the command station or circuit breaker that is feeding your switch and I think you would want to be able to handle short circuit current without your switch failing.

Robin

Robin Becker

San Diego CA

https://DRGW.n3ix.com



Re: Block Detection for signalling and automation

htn1680
 

Blair there is a great new book out about signaling. Guide to signals and interlocking by Dave abeles. It pretty much tell you everything you need to know. Kalmbach publishing issued the book.

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