Who makes a good relay for analog train operation?
Regards,
Dave K.
I don’t know about “good” but I use a plain old Atlas snap relay wired through the turnout switch to reverse polarity inside the loop as the turnout is thrown. Works for DC quite nicely as long as you remember that it reverses polarity inside the loop. You need approaches to the loop exits at least as long as the longest locomotive consist you will run through the loop for this to work because you have to wait for the locomotive consist to clear the isolated section of the loop before throwing the turnout. Main polarity feeds these two sections of track between the turnout routes and the isolation points at each end of the reversing loop section.
When the turnout is thrown on entry to the loop that snap relay matches polarity of the loop to main for that direction. Once the train is entirely in the loop the main polarity is reversed. When the locomotives leave the loop polarity section then polarity of that reversed section is reversed when the turnout is lined for the train to exit. This sets loop polarity for the next train entering. Next train in traverses the loop in the opposite direction and polarity in the loop will be correct.
I could automate this with some sort of sensor and I expect I could automate this with a DCC style auto reversing relay board but I kind of like just driving the train.
A simple center-off, DPDT toggle switch does the trick nicely, changing the polarity in the loop just as Mike described.
Yes, the Atlas snap relay is just such a switch, actually two SPDT in one which allows you to create the DPDT switch using the whole relay by cross wiring the four poles at the active end resulting in polarity reversal when the relay is energized. You run the track end to both sides of the “common terminals” and the powerpack end to the one set of active terminals, cross connecting these to the other set of active terminals. Atlas wiring book shows the schematic. I think the instruction sheet that comes in the box also explains this simple wiring.
With DC, if you plan to reverse the loop polarity, you need to stop the train, reverse the loop polarity, reverse the throtte polarity, then restart the train.
So yes, you can create a semi automatic situation where the turnout position controls the entry/exit polarity, but at some point while the train is in the loop, it has to stop and let the turnout be thrown and the throttle direction reversed for the other direction on the mainline.
Otherwise, when you throw the turnout, the train will change direction.
Sheldon
This turns out to be incorrect. Took me a little while to figure out.
The key aspect is to provide sections of main line powered track inside the actual geometric reversing loop long enough to hold the entire locomotive consist. This requires the reversing section to be shorter than might otherwise fit within a loop created by one turnout. For our back to back loops which basically have a long double isolated X section these main line powered sections are very long so there’s practically no limit to train length, but for our one single turnout loop we sacrifice a little train length capacity to allow for these main line powered sections.
A section of track long enough to contain the locomotive consist just before the exit to the loop is all that is required. For a two way loop you need the same length of main line powered track at the other end of the reversing section. Each one of these sections forms one of the two routes out of the turnout.
The turnout also sets polarity in the reversing section to match train direction entering the loop. The train proceeds into the loop and passes onto the reversing section proper. When the whole powered part of the train (which is the whole thing if you use metal wheels) is within the reversing section, I.e. has cleared the entry section of track powered by the mainl
[quote user=“Lastspikemike”]
ATLANTIC CENTRAL
With DC, if you plan to reverse the loop polarity, you need to stop the train, reverse the loop polarity, reverse the throtte polarity, then restart the train.
So yes, you can create a semi automatic situation where the turnout position controls the entry/exit polarity, but at some point while the train is in the loop, it has to stop and let the turnout be thrown and the throttle direction reversed for the other direction on the mainline.
Otherwise, when you throw the turnout, the train will change direction.
Sheldon
This turns out to be incorrect. Took me a little while to figure out.
The key aspect is to provide sections of main line powered track inside the actual geometric reversing loop long enough to hold the entire locomotive consist. This requires the reversing section to be shorter than might otherwise fit within a loop created by one turnout. For our back to back loops which basically have a long double isolated X section these main line powered sections are very long so there’s practically no limit to train length, but for our one single turnout loop we sacrifice a little train length capacity to allow for these main line powered sections.
A section of track long enough to contain the locomotive consist just before the exit to the loop is all that is required. For a two way loop you need the same length of main line powered track at the other end of the reversing section. Each one of these sections forms one of the two routes out of the turnout.
The turnout also sets polarity in the reversing section to match train direction entering the loop. The train proceeds into the loop an
Gents:
I am researching an Alastranz turnback relay with an infrared sensor. I would prefer an automated process but it starting to get complicated.
Dave
I meant to say Azatrax. I am going to try the Atlas switch method first.
Thanks to all.
Dave
Curious why you want an “analog” or manual reverse loop switch. I have enough problems avoiding running thru closed turnouts to risk having to throw a toggle switch every time one of my trains enters the reverse loop. I plan to install the Azatrax IR detector to handle one turnout at my “yard” that I constantly forget to throw after the train leaves.
Plug-n-Play Digitrax AR1 and NCE AR10 reversers handle reverse loops perfectly with no intervention. Two wires to the reverse loop tracks, nothing exotic, no sensors needed, etc. Just run the trains. I’ve used both.
– Chuck
Because the original poster is running DC, not DCC, so a DCC auto reverser will not work.
That is what he meant by “analog train operation”, his trains are “analog”, not digital.
Sheldon
Thanks, and sorry for posting bad information. I was under the impression the autoreversers would work on either DC or DCC but it ain’t so! [:$] DCC is so simple I forgot some folks like to or at least have to throw dozens of switches to run a couple of trains. Back into trains a couple of years ago and DC was never a consideration.
Chuck, I understand why you like DCC, and I have lots of experience using DCC. But I am building a new layout, 1500 sq ft, 450’ double track mainline, 8-10 operators in play, staging for 30 trains, 40-50 car train lengths, and it will be DC.
And guess what? There will not be one block toggle.
There will be walk around operation with radio throttles, detection, signaling, CTC, ATC (if you run a red single your train stops), one button turnout route control.
As a guest operator on my layout you would likely push less buttons than on a similar DCC layout.
For more info look for my thread about my track plan.
In fact. You might be surprised at the percentage of modelers in HO and N with moderately large layouts who still use DC. Every casual survey we have taken on here, some fairly recent, puts DC use still at 40-45% and not likely to change.
Sheldon
How do I operate the snap switch? In other words the left and right buttons as the train approaches the reversing loop, in the loop, and exiting the loop?
Assuming DC power. Assuming the activation circuit for the snap relay is wired to the turnout switch. Your reference to left and right buttons implies to me that you have an Atlas turnout switch (the one with the blue button). The snap relay has no buttons.
Set the turnout for the desired train direction into the loop. That should match the polarity of the reversing section to that of the main. If it does not then reverse the polarity of the contacts at the actuating side of the snap relay ( there are three wires, black is common, reverse the red and the green).
Once the entire train is within the reversing loop select the opposite direction (polarity) for the main line. Do not line the turnout yet. As the locomotives leave and completely clear the reversing loop and fully enter onto the main line which now has matching polarity you then line the turnout. This then also conveniently reverses the polarity within the reversing loop ready to accept the next train entering from the opposing direction. If the next train is to enter in the same direction as the first train then you must re-line the turnout back to the desired direction which will again match the polarity.
Hello Dave.
I am trying to figure out your question, and filter out the noise in the responses.
It sounds like you have a turn-back reverse loop at the end of your run, and you want to turn the train around in the loop, without stopping, and return on the same track.
You want control of this reverse loop to be simple and preferably automatic.
Is this correct? If not, can you explain your goals a bit more?
Are you comfortable bulding a DC control system for this, or do you need to use something off the shelf?
Is it OK to have a complicated system as long as control is simple, or would you prefer to build something simple and have it a bit more fiddly to control?
I can help, I have done such a thing on real layouts, but I need to understand exactly what your goals are.
Let me know. I am here to help.
I will check back in a few hours when I have time this evening.
-Kevin
Kevin,
You are correct. A smple turn back using DC analog power. I am using Atlas snap switched to accomplish the reveres polarity control.
Dave
Dave, Why is it important to you to try an automate the reverse loop function?
Good DC practice suggests that the reverse switch positon for the mainline should refect the “EAST - WEST” direction of travel, so even with some semi automation of the loop you will need to throw the mainline reverse switch.
I use DC, very complex DC with detection, signals, one button route control, CTC, walk around radio throttles - and I avoid reverse loops as much as possible.
I’m getting ready to start on this basement filling layout - there will only be two reverse loop situations - neither is part of the mainline:
I would be interested to see you track plan and offer my thoughts on a total wiring solution.
Sheldon
Which do you prefer?
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Simpled to install, but not as simple to use.
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More involved to build, but simple to use.
Also, I never use Atlas wiring components. I prefer full size toggle switches.
-Kevin
I have wired the Atlas switches as required. Purchased two. The center slide position shoul be off, yet my center position on both is showin power out? The down position is off. Are these faulty switches?
Dave
K.