Blog & News

About the Model Railroad

RTAC Software


The Randall Museum in San Francisco hosts a large HO-scale model model railroad. Created by the Golden Gate Model Railroad Club starting in 1961, the layout was donated to the Museum in 2015. Since then I have started automatizing trains running on the layout. I am also the model railroad maintainer. This blog describes various updates on the Randall project and I maintain a separate blog for all my electronics not directly related to Randall.

2021-11-15 - Mainline B321 Repair at T322

Category Randall

As explained earlier, we’ve been having issues with the train stopping on a dead spot on the mainline block B321, just after the Branchline turnout T322. I posited the issue was a broken solder joint, and it was indeed the case. A repair has been made -- actually two of them --, we’ll see if that holds.

On the track schematics, repairs were performed at the approximate locations shown below, on the red-side rail.

Trains used to stop dead in that area recently, intermittently. Typically that’s due to a solder joint that is broken and now makes a bad contact. As the track shrinks or expands with humidity, temperature, and the weight of the rolling stock, contact can appear or vanish during the day. The test was simple: with the train dead at that spot, just putting some slight pressure on the track was enough to power the train again. Problem is, that track has been naturally weathered by decades of usage, and it’s nearly impossible to know where the solder joints are, or for what. There can be many, from track feeders, to rail jointers. Not to mention the voluntary block isolation gaps that I need to preserve. Due to the lack of documentation, it means that when I find a gap (or a broken rail that looks like a gap), I don’t really know if it’s on purpose or not.

First repair at spot #1 was done somewhere near the middle of the block. There is a track feeder under the layout going to both the black and red rail. It’s worth pointing two important details at this point:

Click here to continue reading...

2021-11-14 - Motion Sensor

Category Randall

The motion sensor finally has a little cover to keep it in place:

Description of the Motion Sensor and how it is hooked into the NCE AIU01: 

For reference, here’s how the sensor is calibrated:

Click here to continue reading...

2021-11-10 - Maintenance: Automation Stopping on Mainline

Category Randall

Recently a dead spot has developed on the mainline track #1 just in front of Stockton Station.

And last week we had another one: the automation trains are stopping on the mainline between the Branchline Interchange and the Sonora turnout.

As with (the one) previous short we had on the mainline, this one is intermittent, which makes it so fun to find and debug. It works for a while and then suddenly stops. That’s the typical sign of a cold / broken solder joint that moves during the day as the rail expands or shrinks with humidity or temperature. So now I have to look for a solder joint. Could be a track feeder, or it could be a rail joiner, who knows.

The “nice” thing is that I can temporarily fix the dead short just by pressing on the outer rail. So that gives me a clue...

Click here to continue reading...

2021-11-09 - Rain

Category Randall

It’s been raining. And we’ve been reminded the joy of being in a basement:

There’s a full inch of water on the floor. Not exactly a novelty, although when it happened a couple years ago it was supposed to have been taken care of.

The new addition is that water is also dripping on the Napa yard; we guess it comes from the ceiling:

Click here to continue reading...

2021-10-10 - Train Vision Update

Category Randall

The “Train Vision” project uses my custom Train-Motion software running on a laptop, displaying pre-recorded videos I made of trains running on the layout, mixed with live views of trains actually running on the layout.

All the videos come from my Youtube Channel playlist for the museum. I have a couple news train videos to add to that list: an SP Daylight, an Amtrak Superliner, and an SP Cotton Belt. Interestingly since I’ve recently switched to doing shorter videos in the 3-minute range, that works actually better for that kind of display.

One thing I’m particularly proud of is what is not visible here: this runs on a Lenovo Yoga 15 laptop folded over. It provides a good sizable display although it’s not huge so it doesn’t dwarf the layout. This runs the latest Debian Linux distro, and I have spent a lot of time ensuring it powers up automatically with the layout. All the museum staff have to do is turn on power to the exhibit room in the morning, and they don’t have to specifically deal with that computer. Same when they close in the evening. All automated, as it should be. Of course it’s an automation which means sooner or later it will fail to start and it will require manual intervention, however that will be newsworthy because it will be the exception rather than the norm.

This has been running for a couple weeks now and is performing fairly well. Based on my observations:

  • Although some viewers get it instantly, some others are confused on which video shows a live view vs a recorded one. I already added a blinking “Live” sticker to the live views. I’ll follow up by adding a “Recorded” banner on the recorded videos. I’m thinking of a generic “play” triangle icon + record date + title.
  • Originally my first prototype was streaming videos directly off my Youtube Channel playlist. I thought that would be a concern as the recorded videos would stop playing if the wifi was not cooperating. Thus I switched to downloading all the videos and playing them off the drive. Glad I did that because the first week the wifi was really sub-par at the museum although it seems to have somewhat improved since. I have a script I can run that will update my playing list using youtube-dl to download my own videos locally, so updating the playlist is still fairly easy.
  • One thing I do look forward to is working with Tiffany from the Randall Museum Friends to make the display customizable for special events. Says they host a gala or some kind of social event, we can have the software download one or more mp4 (or a private youtube playlist) and play it specifically for that day & time slot.

The last item on the list is the quality of the live video feeds from the cameras on the layout. I was having some terrible frame rates over wireless, with some obvious mp4 dropped frame artifacts. I switched one of the cameras from wireless to wired ethernet, and I also switched the laptop to wired ethernet using a Linux-compatible Cable Matters USB to Ethernet Adapter (linux pro-tip: this one requires an apt install firmware-realtek from Debian 11 “bullseye”). That combination brought me the stable 15 fps I was looking for. I will wire the other two cameras once I have them in their final location.

2021-09-22 - Bridgeport Maintenance

Category Randall

Time for more maintenance. This time I adjusted the grade crossing light sensitivity with some room lights off, and it seemed to go better. In this case I had the fluorescent lights off, the single center spot on, and the side spots (by the walls) on medium.

More importantly we had an interesting case: a turnout malfunctioned on the Bridgeport lead track.

That seems innocuous except this somehow shorted the B450 block on the mainline (the one that leads to Bridgeport) on the Mountain Panel 2, and it also made blocks B330 and B360 seem occupied on the Mountain Panel 1 -- these two blocks are used by the automation and since the track appeared occupied the automated trains would not start. It did take me some time to figure all that out since I started in reverse (why the blocks seemed occupied) and I had to trace it back to the short on the other panel and then to the Bridgeport lead. I still don’t have a full explanation here. It just doesn’t quite make sense.

Anyhow, this is what I found on the Bridgeport lead:

What’s wrong with the point?

Click here to continue reading...

2021-09-21 - Maintenance

Category Randall

Yesterday was also time for some regular maintenance.

First order of business was to swap the engine for the automated UP passenger train. It has been running with UP 8736 for quite a while, and I swapped it for UP 8749. They are both identical SD70ACe engines, and I had previously programmed them to have identical running characteristics, so it was a quick one-line change in the automation computer’s event script.

Then I had been told the grade crossing bell was ringing all the time with no trains, so I spent quite some time adjusting it. One of the sensors is way more sensitive than the others. I readjusted them all. Unfortunately I’m told today that the bell was again ringing for almost 20 minutes when the layout was turned on. I had noticed that before -- when we turn everything on in the room, the lights are not as bright and they take time to warm up. And that can be enough to trip the grade crossing light sensors. Ideally I’d have to adjust the sensor right when the lights are turned on in the morning.

So I need to adjust the grade crossing sensors again. I’ll see if I can reduce the dimmable spots or turn off some lights to reproduce that “warming up” state from the morning.

2021-09-20 - Train Vision

Category Randall

The “Train Vision” project: One part is my custom Train-Motion software that runs on a laptop, displaying pre-recorded videos fullscreen. A second part are cameras located on the layout display live trains as they go by. When the live trains are visible, motion detection kicks in and the display changes from fullscreen to a 4-video quadrant with one view being the recorded video and the 3 other being the 3 live cameras.

I’ve spent the first half of the year reworking the Train-Motion software from the prototype I did last year, and it’s now good enough to install it at the museum. It’s not perfect, yet we need to see it in real condition to adjust it.

The display is a 17-inch laptop. A lot of time was spent to make sure it would work as automatically as possible. It is now configured to start when the power to the layout is turned on, and it shuts off automatically with the layout power. It auto-boots Linux and my dedicated Train-Motion program. The museum staff will not have to interact with the laptop -- no need to manually turn it on or off like they do with some other exhibits.

I quickly placed the 3 live cameras on the layout by the Fairfield passenger station. That’s temporary.

Click here to continue reading...

2021-07-06 - Repair for Turnout T450

Category Randall

The Bridgeport turnout needed fixing, and it is now fully functional again.

It uses a Fulgurex turnout, and recently this one had started shorting the entire turnout power supply intermittently.

This is a Fulgurex slow-motion motor. Connections have two wires for turnout power, and two sets of contacts (three wires each) that are commutated based on the position of the switch:

And here it is after the fix, when testing it:

Click here to continue reading...

2021-07-05 - Randall Scenery Lights in “dusk”

Category Randall

Lighting on the Stockton side:

The Fairfield main street with street lighting on, and the illuminated McDonalds:

Click here to continue reading...

 Generated on 2021-11-29 by Rig4j 0.1-Exp-666f4a7