Topics

Wiring AR segments -- Can two AR segments be adjacent to one another?

mgj21932
 

I am about to start wiring my conversion of an older DC layout (HO scale) to DCC.  The layout is basically a figure 8 mainline with two reversing loops (and sidings unaffected by this issue).  I am using Tam Valley frog juicers (Hex Juicer) for AR circuitry with helpful guidance from Duncan McRee at Tam Valley.  Thanks to Max Maginness' advice, I reduced the planned wiring from six AR segments (overkill) to three.  But now I think what I really need is just TWO AR circuits.  

Question:  This may be a silly question, but must there be a non-reversing segment between AR segments?  Or, stated differently, may two AR segments be contiguous?  

My two cents:  If two AR segments are adjacent to one another, as the momentary short is created by the front wheels of the engine crossing from one segment into a segment of different polarity, wouldn't the AR switches in the two segments "fight" with one another, i.e., wouldn't both attempt to switch "polarity" (cycle pattern) to address the short at the same time?  

Previously I had naively conceptualized that the AR switch in the "new" segment (the one into which the engine is proceeding) would switch polarity to "resolve" the conflict.  But it occurs to me that the segment from which the train is departing doesn't know (or care) which direction the train is moving.  (I understand that under DCC even the train doesn't care, as direction is independent of polarity.)  That suggests that the AR switch for the "departing" segment would likewise be activated by the same momentary short.    

In the recent discussions of wiring AR segments on this blog, we talked about various limitations, including an extended discussion about the minimum length of the AR segment needing to be longer than the length of the longest train.  I don't recall, however, any discussion about AR segments not being adjacent to one another -- and do not recall reading that as a limitation in any of the several DCC Wiring manuals I've studied.  Perhaps that is so fundamental as to be self-evident.  But initially I didn't appreciate that fact (if it is a fact) as the foregoing indicates.

Proposed Solution:  I think I need to wire my figure 8 mainline as a non-reversing segment.  Then, if I isolate the two reversing loops and wire both as AR segments, only they will automatically switch the polarity (whichever direction it happens to be in), to match that of the constant polarity of the figure 8 mainline.  If the polarity of the AR spur is opposite that of the mainline, whether the train is entering or leaving the loop, the momentary short experienced on the loop will result in the AR switch rectifying the short before the short experienced by the mainline trips the circuit breaker of the mainline.  

Do I have that correct?   Would appreciate confirmation of my conclusion, and that wiring the mainline as a non-AR segment, while relying on the AR switches for the reversing loops to address the polarity issue in both directions, will address the issue.   

A benefit of this arrangement is that, because the reversing segments are short (relative to the mainline), I will not have more than one train in the AR segment at any time.  Therefore I shouldn't have to worry about any limit on the current the TV Frog Juicer can provide to that segment (although I believe it would be more than adequate to support two trains).  Similar concerns would not afflict the non-AR mainline as it would be powered directly from the Track Bus at well-spaced feeder intervals.   

Bill Demarest

Don Batman
 

PSX-AR “DoubleReverse” On some layouts there are situations that
require two PSXAR’s be connected back to back. This can cause a
condition where both reveres tryto fix the short byreversing the
lines. Theyboth keep trying to fix the problem and continue to flip
back and forth, causing a delay. The newer PSX-AR’s have a CV that can
be set to delaythe action of the reverser. Only one of the two
reversers needs to have this CV set to on. This allows the other
reverser to change status during the short delayand resolve the
conflict.

On 2/8/20, mgj21932 via Groups.Io <mgj21932=yahoo.com@groups.io> wrote:
I am about to start wiring my conversion of an older DC layout (HO scale) to
DCC. The layout is basically a figure 8 mainline with two reversing loops
(and sidings unaffected by this issue). I am using Tam Valley frog juicers
(Hex Juicer) for AR circuitry with helpful guidance from Duncan McRee at Tam
Valley. Thanks to Max Maginness' advice, I reduced the planned wiring from
six AR segments (overkill) to three. But now I think what I really need is
just TWO AR circuits.
Question: This may be a silly question, but must there be a non-reversing
segment between AR segments? Or, stated differently, may two AR segments be
contiguous?
My two cents: If two AR segments are adjacent to one another, as the
momentary short is created by the front wheels of the engine crossing from
one segment into a segment of different polarity, wouldn't the AR switches
in the two segments "fight" with one another, i.e., wouldn't both attempt to
switch "polarity" (cycle pattern) to address the short at the same time?
Previously I had naively conceptualized that the AR switch in the "new"
segment (the one into which the engine is proceeding) would switch polarity
to "resolve" the conflict. But it occurs to me that the segment from which
the train is departing doesn't know (or care) which direction the train is
moving. (I understand that under DCC even the train doesn't care, as
direction is independent of polarity.) That suggests that the AR switch for
the "departing" segment would likewise be activated by the same momentary
short.
In the recent discussions of wiring AR segments on this blog, we talked
about various limitations, including an extended discussion about the
minimum length of the AR segment needing to be longer than the length of the
longest train. I don't recall, however, any discussion about AR segments
not being adjacent to one another -- and do not recall reading that as a
limitation in any of the several DCC Wiring manuals I've studied. Perhaps
that is so fundamental as to be self-evident. But initially I didn't
appreciate that fact (if it is a fact) as the foregoing indicates.
Proposed Solution: I think I need to wire my figure 8 mainline as a
non-reversing segment. Then, if I isolate the two reversing loops and wire
both as AR segments, only they will automatically switch the polarity
(whichever direction it happens to be in), to match that of the constant
polarity of the figure 8 mainline. If the polarity of the AR spur is
opposite that of the mainline, whether the train is entering or leaving the
loop, the momentary short experienced on the loop will result in the AR
switch rectifying the short before the short experienced by the mainline
trips the circuit breaker of the mainline.
Do I have that correct? Would appreciate confirmation of my conclusion,
and that wiring the mainline as a non-AR segment, while relying on the AR
switches for the reversing loops to address the polarity issue in both
directions, will address the issue.
A benefit of this arrangement is that, because the reversing segments are
short (relative to the mainline), I will not have more than one train in the
AR segment at any time. Therefore I shouldn't have to worry about any limit
on the current the TV Frog Juicer can provide to that segment (although I
believe it would be more than adequate to support two trains). Similar
concerns would not afflict the non-AR mainline as it would be powered
directly from the Track Bus at well-spaced feeder intervals.
Bill Demarest



mgj21932
 

Thanks Don.

On Feb 8, 2020, at 6:00 PM, Don Batman <donbatman1952@...> wrote:

PSX-AR “DoubleReverse” On some layouts there are situations that
require two PSXAR’s be connected back to back. This can cause a
condition where both reveres tryto fix the short byreversing the
lines. Theyboth keep trying to fix the problem and continue to flip
back and forth, causing a delay. The newer PSX-AR’s have a CV that can
be set to delaythe action of the reverser. Only one of the two
reversers needs to have this CV set to on. This allows the other
reverser to change status during the short delayand resolve the
conflict.

On 2/8/20, mgj21932 via Groups.Io <mgj21932=yahoo.com@groups.io> wrote:
I am about to start wiring my conversion of an older DC layout (HO scale) to
DCC. The layout is basically a figure 8 mainline with two reversing loops
(and sidings unaffected by this issue). I am using Tam Valley frog juicers
(Hex Juicer) for AR circuitry with helpful guidance from Duncan McRee at Tam
Valley. Thanks to Max Maginness' advice, I reduced the planned wiring from
six AR segments (overkill) to three. But now I think what I really need is
just TWO AR circuits.
Question: This may be a silly question, but must there be a non-reversing
segment between AR segments? Or, stated differently, may two AR segments be
contiguous?
My two cents: If two AR segments are adjacent to one another, as the
momentary short is created by the front wheels of the engine crossing from
one segment into a segment of different polarity, wouldn't the AR switches
in the two segments "fight" with one another, i.e., wouldn't both attempt to
switch "polarity" (cycle pattern) to address the short at the same time?
Previously I had naively conceptualized that the AR switch in the "new"
segment (the one into which the engine is proceeding) would switch polarity
to "resolve" the conflict. But it occurs to me that the segment from which
the train is departing doesn't know (or care) which direction the train is
moving. (I understand that under DCC even the train doesn't care, as
direction is independent of polarity.) That suggests that the AR switch for
the "departing" segment would likewise be activated by the same momentary
short.
In the recent discussions of wiring AR segments on this blog, we talked
about various limitations, including an extended discussion about the
minimum length of the AR segment needing to be longer than the length of the
longest train. I don't recall, however, any discussion about AR segments
not being adjacent to one another -- and do not recall reading that as a
limitation in any of the several DCC Wiring manuals I've studied. Perhaps
that is so fundamental as to be self-evident. But initially I didn't
appreciate that fact (if it is a fact) as the foregoing indicates.
Proposed Solution: I think I need to wire my figure 8 mainline as a
non-reversing segment. Then, if I isolate the two reversing loops and wire
both as AR segments, only they will automatically switch the polarity
(whichever direction it happens to be in), to match that of the constant
polarity of the figure 8 mainline. If the polarity of the AR spur is
opposite that of the mainline, whether the train is entering or leaving the
loop, the momentary short experienced on the loop will result in the AR
switch rectifying the short before the short experienced by the mainline
trips the circuit breaker of the mainline.
Do I have that correct? Would appreciate confirmation of my conclusion,
and that wiring the mainline as a non-AR segment, while relying on the AR
switches for the reversing loops to address the polarity issue in both
directions, will address the issue.
A benefit of this arrangement is that, because the reversing segments are
short (relative to the mainline), I will not have more than one train in the
AR segment at any time. Therefore I shouldn't have to worry about any limit
on the current the TV Frog Juicer can provide to that segment (although I
believe it would be more than adequate to support two trains). Similar
concerns would not afflict the non-AR mainline as it would be powered
directly from the Track Bus at well-spaced feeder intervals.
Bill Demarest




mgj21932
 

I’m not using PSX-ARs so I don’t have that capability (that I know of anyway). But you seem to confirm my basic analysis and as I don't believe it essential for the figure 8 mainline to be AR, will avoid the problem.

On Feb 8, 2020, at 6:00 PM, Don Batman <donbatman1952@...> wrote:

PSX-AR “DoubleReverse” On some layouts there are situations that
require two PSXAR’s be connected back to back. This can cause a
condition where both reveres tryto fix the short byreversing the
lines. Theyboth keep trying to fix the problem and continue to flip
back and forth, causing a delay. The newer PSX-AR’s have a CV that can
be set to delaythe action of the reverser. Only one of the two
reversers needs to have this CV set to on. This allows the other
reverser to change status during the short delayand resolve the
conflict.

On 2/8/20, mgj21932 via Groups.Io <mgj21932=yahoo.com@groups.io> wrote:
I am about to start wiring my conversion of an older DC layout (HO scale) to
DCC. The layout is basically a figure 8 mainline with two reversing loops
(and sidings unaffected by this issue). I am using Tam Valley frog juicers
(Hex Juicer) for AR circuitry with helpful guidance from Duncan McRee at Tam
Valley. Thanks to Max Maginness' advice, I reduced the planned wiring from
six AR segments (overkill) to three. But now I think what I really need is
just TWO AR circuits.
Question: This may be a silly question, but must there be a non-reversing
segment between AR segments? Or, stated differently, may two AR segments be
contiguous?
My two cents: If two AR segments are adjacent to one another, as the
momentary short is created by the front wheels of the engine crossing from
one segment into a segment of different polarity, wouldn't the AR switches
in the two segments "fight" with one another, i.e., wouldn't both attempt to
switch "polarity" (cycle pattern) to address the short at the same time?
Previously I had naively conceptualized that the AR switch in the "new"
segment (the one into which the engine is proceeding) would switch polarity
to "resolve" the conflict. But it occurs to me that the segment from which
the train is departing doesn't know (or care) which direction the train is
moving. (I understand that under DCC even the train doesn't care, as
direction is independent of polarity.) That suggests that the AR switch for
the "departing" segment would likewise be activated by the same momentary
short.
In the recent discussions of wiring AR segments on this blog, we talked
about various limitations, including an extended discussion about the
minimum length of the AR segment needing to be longer than the length of the
longest train. I don't recall, however, any discussion about AR segments
not being adjacent to one another -- and do not recall reading that as a
limitation in any of the several DCC Wiring manuals I've studied. Perhaps
that is so fundamental as to be self-evident. But initially I didn't
appreciate that fact (if it is a fact) as the foregoing indicates.
Proposed Solution: I think I need to wire my figure 8 mainline as a
non-reversing segment. Then, if I isolate the two reversing loops and wire
both as AR segments, only they will automatically switch the polarity
(whichever direction it happens to be in), to match that of the constant
polarity of the figure 8 mainline. If the polarity of the AR spur is
opposite that of the mainline, whether the train is entering or leaving the
loop, the momentary short experienced on the loop will result in the AR
switch rectifying the short before the short experienced by the mainline
trips the circuit breaker of the mainline.
Do I have that correct? Would appreciate confirmation of my conclusion,
and that wiring the mainline as a non-AR segment, while relying on the AR
switches for the reversing loops to address the polarity issue in both
directions, will address the issue.
A benefit of this arrangement is that, because the reversing segments are
short (relative to the mainline), I will not have more than one train in the
AR segment at any time. Therefore I shouldn't have to worry about any limit
on the current the TV Frog Juicer can provide to that segment (although I
believe it would be more than adequate to support two trains). Similar
concerns would not afflict the non-AR mainline as it would be powered
directly from the Track Bus at well-spaced feeder intervals.
Bill Demarest




Don Vollrath
 

Bill. Your understanding is correct. Making an AR section at each end of the figure eight allows you to separate them from each other via fixed polarity of the mainlines. It is possible for two AR sections to abut one another provided the AR controllers can be adjusted to have separate timing. Otherwise as you say they may continuously fight each other.

DonV

mgj21932
 

Thanks Don. I will redesign wiring plan accordingly. Want to avoid risk of the AR Switches competing when not necessary.
Bill

On Feb 9, 2020, at 9:22 AM, Don Vollrath <donevol43@...> wrote:

Bill. Your understanding is correct. Making an AR section at each end of the figure eight allows you to separate them from each other via fixed polarity of the mainlines. It is possible for two AR sections to abut one another provided the AR controllers can be adjusted to have separate timing. Otherwise as you say they may continuously fight each other.

DonV