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On other forums and discussion groups, I've been discussing and soliciting advice on one of my current obsessions: exploring the old-school technology embedded in the venerable Marx "Twin Trains" set. For those unfamiliar with that post-war item, in addition to the "twin trains" of the title, the set came equipped with a figure-8 of track (including an X crossover between the two loops), a transformer, a lighted control signal, and a set of accessories. The unique selling point of this set was that both trains could be run on the same track at the same time -- when the trains were in danger of colliding at the crossing, a signal block light would change from green to red and one of the trains would be stopped (by a relay inside the signal block) short of the crossing until the first train cleared the intersection. In effect, the Marx set uses simple electro-mechanical technology to simulate a form of simple block control, in a manner strikingly similar to that employed by prototype railroads in the early to mid-twentieth century.

To detail my explorations and conclusions, I've attached a write-up of my project experiences so far. Just for giggles, I decided to do it up like a term paper, footnotes and appendices and all. The careful observer might notice that portions of the paper strongly resemble portions of previous on-line discussions here and elsewhere, though I was far from compulsive about attributing other's numerous specific contributions to the project (sorry -- but thanks again to all who weighed in!). I've also included references to and copies of some relevant source materials, if you'd like to do a deeper dive. If/when I get around to attempting to incorporate the "Twin Train" set functionality I've been exploring in my bread-boarded experimentation onto my layout, I'll add an addendum (and probably a video or two!). Enjoy!
 

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MTH O gauge engines,mongrel rolling stock
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Several years ago where I volunteered, a supervisor asked if I could get his boyhood Marx set going. I was puzzled by two different engines and the "funky" signal light which didn't come up in my wife's Marx's price book. All the supervisor said was that trains raced around figure 8, but stopped at crossover to avoid colliding with other engine. Cleaning up, lubricating and test running engines was the easy part. SO, after figuring out what was inside signal (there was no instruction paper) I was able to figure out there were isolated track sections where the special track clips went, I finally got it running after many near collisions. I gave back the set to him with a pencil drawing of how to wire it up if he wanted to run it for grand kids.

Amazing what Marx could do "on the cheap". Don't recall if Lionel or anyone else had similar ready to run two engine stop/go sets, though would not be hard to figure out how to set up such a deal. I know there were Lionel (and probably AF) signals that would stop this train for a time delay, but not sophisticated as Marx's two engine set.
 

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Enjoyed the write-up, nicely done. Gave me ideas as well :)

Here's my Video of a custom (mostly Marx) Christmas train. Santa, the reindeer and a boat load, oh, wait, excuse me, a train load of presents stops at Santa's Sleigh Station for replenishments.

A simple station stop circuit using isolated rails to power ac-dc voltage regulators that power DC relay modules.
 

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Discussion Starter · #4 ·
Several years ago where I volunteered, a supervisor asked if I could get his boyhood Marx set going. I was puzzled by two different engines and the "funky" signal light which didn't come up in my wife's Marx's price book. All the supervisor said was that trains raced around figure 8, but stopped at crossover to avoid colliding with other engine. Cleaning up, lubricating and test running engines was the easy part. SO, after figuring out what was inside signal (there was no instruction paper) I was able to figure out there were isolated track sections where the special track clips went, I finally got it running after many near collisions. I gave back the set to him with a pencil drawing of how to wire it up if he wanted to run it for grand kids.

Amazing what Marx could do "on the cheap". Don't recall if Lionel or anyone else had similar ready to run two engine stop/go sets, though would not be hard to figure out how to set up such a deal. I know there were Lionel (and probably AF) signals that would stop this train for a time delay, but not sophisticated as Marx's two engine set.
Yep, sounds like you resurrected one of the venerable (even years ago!) Marx "Twin Train" sets, and kudos to you for figuring out the wiring without instructions -- it's far from intuitive, as the Gilmer paper makes clear! BTW, Gilmer (and, I believe, the earlier Twarog papers he cites) concluded that Marx viewed the set merely as a one-off and a novelty, and apparently never attempted to expand the core functionality into other situations and sets. In a way, one can understand why, once you realize how fiddly the set can be if you try to run non-standard rolling stock on it, and potentially that only gets worse if you modify or attempt to adapt the hardware into other layout configurations and functions.

My own searches have shown the basic tech was fully developed for Lionel (and probably also AF) hardware, but if either ever issued a "Twin Train"-type set, I'm unaware of it. And yes, I believe all those manufacturers had hardware available that would provide manual block control (basically, a signal light block with a manual switch to cut off (or sometimes reduce) track power, stopping (or slowing) any train in the block and changing the signal light from green to red (or sometimes yellow). AFAIK, none provided for remote or automatic control, and IMHO none could be considered a true block control system or component.
 

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Discussion Starter · #5 ·
Enjoyed the write-up, nicely done. Gave me ideas as well :)

Here's my Video of a custom (mostly Marx) Christmas train. Santa, the reindeer and a boat load, oh, wait, excuse me, a train load of presents stops at Santa's Sleigh Station for replenishments.

A simple station stop circuit using isolated rails to power ac-dc voltage regulators that power DC relay modules.
Nice video, Mike, and thanks for the complements! I'd be very interested in exactly how you implemented the stop-and-delay system on your layout. While I'm still up to my keister in plans to shoe-horn "Twin Train" functionality into my layout, I've already started to eye my two trolley lines for implementing some sort of stop-and-delay functionality (I already use the built-in bump and reverse function to run them back and forth, but I'd much prefer the more realistic motion your system provides).

BTW, that's a nice crane, which reminds me of the one MarxMotorMan Bob Testa has recently been constructing and is currently in the process of automating. You two should talk! :sneaky:
 

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Nice video, Mike, and thanks for the complements! I'd be very interested in exactly how you implemented the stop-and-delay system on your layout. While I'm still up to my keister in plans to shoe-horn "Twin Train" functionality into my layout, I've already started to eye my two trolley lines for implementing some sort of stop-and-delay functionality (I already use the built-in bump and reverse function to run them back and forth, but I'd much prefer the more realistic motion your system provides).

BTW, that's a nice crane, which reminds me of the one MarxMotorMan Bob Testa has recently been constructing and is currently in the process of automating. You two should talk! :sneaky:
The "schematic": Pictured below. I'm using low cost, mass produced modules for Arduino hobbyists.

The Modules: The AC-DC 12 Regulator is an integrated, adjustable regulator with an on board bridge rectifier and a nice sized capacitor to ward off any intermittent isolated rail contact. The (Type 1) Delay Relay Module provides the delay function. Once powered, it switches it's SPDT relay to the NO position after an adjustable delay. It will hold in that position as long as it continues to have power. The delay can be set from sub second to ~ 10 secs using the on-board trim resistor. Removing power resets the module. These mass produced modules are cheap totaling ~$6 for both including shipping as long as you can wait several weeks for "The slow boat from China".

Note: There are two types of delay relay modules. The Type 1 as described above, switches after the delay expires. The Type 2 module switches immediately on power up and reverts back to the nominal position after the delay expires. A close read of the Ali Express offer descriptions is warranted when purchasing a delay module. I can't tell the difference between the two types once in hand. I have to bench test the operation after grabbing one from my parts stock :)

Operation: When a loco enters the isolated section, it loses power on the isolated center rail. At the same time, it connects the insulated outside rail and powers up the regulator and, hence, the relay module. The relay module's timer begins. Once expired, the module switches it's relay to the NO position providing center rail power to the loco. The loco starts and moves on. After the train clears the isolated rail section, power is removed from the regulator and the relay module resets for the next occurrence.

Rectangle Slope Parallel Font Number


Here's a Video of an application for the type 2 delay relay module. I modified the relay module by adding one 10K resistor to make it a bi-stable oscillator. Using an insulated outside rail in conjunction with a voltage regulator, it provides realistic operation of a classic crossing signal.
 

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Discussion Starter · #8 ·
The "schematic": Pictured below. I'm using low cost, mass produced modules for Arduino hobbyists.

The Modules: The AC-DC 12 Regulator is an integrated, adjustable regulator with an on board bridge rectifier and a nice sized capacitor to ward off any intermittent isolated rail contact. The (Type 1) Delay Relay Module provides the delay function. Once powered, it switches it's SPDT relay to the NO position after an adjustable delay. It will hold in that position as long as it continues to have power. The delay can be set from sub second to ~ 10 secs using the on-board trim resistor. Removing power resets the module. These mass produced modules are cheap totaling ~$6 for both including shipping as long as you can wait several weeks for "The slow boat from China".
Thanks, Mike, exactly what I asked for! :)(y)

I've sent off for two sets of parts, and with a $3 off coupon, paid just over $5 for everything, including (slow boat) shipping! I'll let you know how it goes in setting up my trolley stops, and thanks again!
 

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Thanks, Mike, exactly what I asked for! :)(y)

I've sent off for two sets of parts, and with a $3 off coupon, paid just over $5 for everything, including (slow boat) shipping! I'll let you know how it goes in setting up my trolley stops, and thanks again!
White Cartoon Happy Font Automotive decal



Since I'm resigned to a seasonal layout, I don't have benchwork to mount and/or hide the modules. So I've been stuffing the electronics into little project boxes and using Walgreens photo printing for legends ($0.40 for a 4"x6" print). If you simply want to mount the modules you can use a good brand of double sided tape or #4 screws. I use the 3M double sided tape to mount the modules inside the project boxes. To make the tape stick reliably, I take a broad file an file down the solder & leads on the underside of the module nearly to the PCB. Afterwards I wash it down with 90% IPA.

I built the box below for Madman's Lionel Train Orders Building accessory. It uses the type 2 delay relay and regulator. The reason for the Type 2 module is to supply a short duration connection (like a button push) across the accessory's control input. A train on the isolated rail will power up the regulator and the relay module will immediately switch to the NO position (connected to the accessories input). The timer is set for ~ 1 sec and the relay reverts back. This prevents the accessory's "man" from completing an in or out cycle and then starting the next cycle. Solving the problem of a long train, slow train or stopped train on the insulated rail.

You can't directly power the building from an isolated rail as it's internals are DC having been full wave rectified. And once you have full wave rectification of the AC power feed, none of the downstream electronics can connect back to the AC. It will short. But the relay contacts are isolated from the AC input and DC modules' control circuitry.

And I'm building the crossing gate flasher into a box for sjm9911.


Motor vehicle Rectangle Font Asphalt Gas
 

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Discussion Starter · #10 ·
Since I'm resigned to a seasonal layout, I don't have benchwork to mount and/or hide the modules. So I've been stuffing the electronics into little project boxes and using Walgreens photo printing for legends ($0.40 for a 4"x6" print). If you simply want to mount the modules you can use a good brand of double sided tape or #4 screws. I use the 3M double sided tape to mount the modules inside the project boxes. To make the tape stick reliably, I take a broad file an file down the solder & leads on the underside of the module nearly to the PCB. Afterwards I wash it down with 90% IPA.
Since I have a freestanding, at least semi-permanent, layout, I'll probably just mount the "works" on the underside of the table. OTOH, in several instances I've just crafted a 'utility box' out of a suitable texture file downloaded from the internet, printed on card stock and crafted into a box shape. I used this technique to hid a flasher module at the top of a cell tower I created (sorry for the poor quality -- the photo is a crop from the best pic I had available):

Building Wood Asphalt House Hardwood


I also added a utility box at the bottom of the tower, in the same fashion:

Plant Natural landscape Land lot Slope Grass


(Here's a short video I put together featuring shots of the cell tower installation:
)
 

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I consulted to Verizon Wireless in the early days of cell phone service when there were fewer, higher towers. One tower tech told me it took him a 1/2 hour to climb to the top. And then he needed to rest for another 1/2 hour once he got there :)
 

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Discussion Starter · #12 ·
I consulted to Verizon Wireless in the early days of cell phone service when there were fewer, higher towers. One tower tech told me it took him a 1/2 hour to climb to the top. And then he needed to rest for another 1/2 hour once he got there :)
Heck, that's nothing! I built that tower more than a year ago now, and the climbing guy hasn't made it to the top yet. The guy at the top looks so distressed because the climbing guy was supposed to bring him lunch! o_O
 

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Discussion Starter · #14 ·
Just for the sake of toy train geekery - sorta similar but unrelated: the 00 Trix Twin 3-rail system that used isolated return rails with left and right hand pickups on the two locomotives.

FW
When I tried the link, my antivirus went off like a rocket. Perhaps check that you've not been infected?
 

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Discussion Starter · #16 ·
The "schematic": Pictured below. I'm using low cost, mass produced modules for Arduino hobbyists.

The Modules: The AC-DC 12 Regulator is an integrated, adjustable regulator with an on board bridge rectifier and a nice sized capacitor to ward off any intermittent isolated rail contact. The (Type 1) Delay Relay Module provides the delay function. Once powered, it switches it's SPDT relay to the NO position after an adjustable delay. It will hold in that position as long as it continues to have power. The delay can be set from sub second to ~ 10 secs using the on-board trim resistor. Removing power resets the module. These mass produced modules are cheap totaling ~$6 for both including shipping as long as you can wait several weeks for "The slow boat from China".



View attachment 586292

Here's a Video of an application for the type 2 delay relay module. I modified the relay module by adding one 10K resistor to make it a bi-stable oscillator. Using an insulated outside rail in conjunction with a voltage regulator, it provides realistic operation of a classic crossing signal.
Mike, the boat made better time from China than expected: the modules arrived yesterday, and I've bread-boarded them in what I think approximates your schematic, with the exception that, rather than powering the rectifier module from accessory voltage (which I assume you meant by "ACC Power" in your schematic), I'm just grabbing the center rail AC power (by running a jumper from one of the "AC in" terminals to the terminal labeled "NO" on your schematic) and routing it through the rectifier module to the isolated outer rail track section, so the circuit will be completed (and power provided to the time delay relay module) when the trolley enters the isolated section. Here's a photo of my lash-up:

Circuit component Light Passive circuit component Lighting Hardware programmer


Note that the left-most black wire running under the track section at the top is connected to a crimp-on connector inserted from underneath between the sides of the top-most outer rail, which is the isolated section (the insulation I inserted is transparent plastic, and barely visible), while the right-most black wire is similarly connected to the isolated center rail, and the blue crimp-on connector floating at the top is intended to be inserted from underneath between the sides of the "hot" center rail in the next section of track, to provide power for the modules and center rail power to the isolated section after the timer cuts it in. I'd appreciate it if you'd let me know if you see anything egregiously wrong or questionable!

Even if I've managed to properly connect everything, I still have a couple of questions:

- First, are the power module's default settings suitable to this setup, or do I need to measure and adjust the output voltage before powering the delay module? In any event, do I assume correctly that the little brass adjustment screw on the top of the small blue rectangular box is the voltage adjustment? What is the proper DC voltage for the timer module (and can I assume the similar adjustment screw on the similar blue box will change the delay time)?

- Second, the markings on the timer module's three-connector block are somewhat different than those on your schematic, but I followed the location pattern shown on your schematic (left and center, with the right unused). Do I need to make further inquiries or adjustments, or is it safe to assume it'll work as connected, straight out of the box? And just out of curiosity, what does the unused terminal connect to? Is this an SPDT relay, with the unused terminal the "normally open" connection (in other words, the relay connects it to the center terminal only when the relay is powered, and only until the delay period is over)?

Thanks for your advice and guidance so far, and thanks in advance for your review and suggestions!
 

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If you come this far along, I'll assume you have a VOM.

You do need to adjust the regulator's output to 12 V to avoid overdriving the relay's coil. The relay module has it's own 5 V regulator (SMD chip) for the TTL timer circuit, but the relay's coil directly gets the DC input to the module.

Note: My first attempt was using 5 V relay modules to insure track power had enough peak AC voltage to activate the circuits. But low and behold, the relay module would not work at 5 V design defect.. The timer counted but the relay trip circuit wouldn't drive the relay coil. I replaced an LED that fixed that and, I believe, the latest 5 V relay modules have be fixed. But it caused me to go 12 V and accessory power. The circuit was used to trip switches/turnout coils so ACC at 16 became my norm.

You'll have to see whether track voltage works for you. Not an issue in the command mode where track voltage is fixed at 18 V. But can be an issue in conventional operation with lower voltages.
 

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Discussion Starter · #18 ·
If you come this far along, I'll assume you have a VOM.

You do need to adjust the regulator's output to 12 V to avoid overdriving the relay's coil. The relay module has it's own 5 V regulator (SMD chip) for the TTL timer circuit, but the relay's coil directly gets the DC input to the module.

Note: My first attempt was using 5 V relay modules to insure track power had enough peak AC voltage to activate the circuits. But low and behold, the relay module would not work at 5 V design defect.. The timer counted but the relay trip circuit wouldn't drive the relay coil. I replaced an LED that fixed that and, I believe, the latest 5 V relay modules have be fixed. But it caused me to go 12 V and accessory power. The circuit was used to trip switches/turnout coils so ACC at 16 became my norm.

You'll have to see whether track voltage works for you. Not an issue in the command mode where track voltage is fixed at 18 V. But can be an issue in conventional operation with lower voltages.
Yep on the VOM (if a thirty+-year-old multimeter counts!). May I assume the brass screw on the blue box is the adjustment mechanism? In any event, I'll check and adjust the output voltage to as close to 12 volts as I can get befre trying to test the set-up.

Yes, I'm running 3-rail O scale legacy track, in purely conventional operation with all legacy equipment, and I tend to run things like trolleys at the lowest reliable speed to add to the realism. I take it from your comment that, if for some reason the relay fails to reliably stop the trolley, upping the throttle setting might be the cure?

So, other than the voltage adjustment, did you see anything in my wiring lash-up that would give you pause?

Oh, and do you have at hand spec's on the crossing flasher arrangement shown in your video? I'm seriously thinking of switching out the legacy top-of-the-rail contacts to instead just grab power from the crossing gate isolated section and run it through your version of flasher setup. Thanks for all your help!
 

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Discussion Starter · #19 ·
Never mind, Mike -- I managed to figure it out:


For those playing along at home: yes, the brass screws on the blue boxes were the adjustments, and yes, the initial voltage was less than 5 volts, but I was able to bring it up to 12, and the initial delay was about two seconds but I was able to adjust it up to about five. The wiring schematic was a bit off on the relay contacts (I suspect Mike was working with a different batch), but I was able to sort it. The biggest problems were self-created, because I decided to create the test stop next to several isolated sections, and they didn't want to play well together!
 
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