Model Train-related Notes (a.k.a. “blog”) -- these are personal notes and musings on the subject of model train control, automation, electronics, or whatever I find interesting.

2018-12-09 - SQ23 Mini Camera for Cab Rides

Category Video

After trying the SQ12 camera, I moved on to its newer sibling, the SQ23. The goal is to use it to record cab rides. As this one has wifi, a secondary goal is to see if it’s suitable as a “live camera” e.g. to broadcast a ride view to a screen.

This is the SQ23 Camera I got from Amazon (can be found cheaper elsewhere, e.g. on Aliexpress), compared to my  Mobius Action Cam and the SQ12 camera:

From left to right: SQ12, SQ23, Mobius compared to an HO-size engine + gondola

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2018-12-01 - SQ12 Mini Camera for Cab Rides

Category Video

I’ve been doing all my “cab ride” recordings using a Mobius Action Cam. A few months ago I tried the RunCam 2 for comparison.
This time I decided to try one of the SQ “mini” cameras series for a change.

Cab ride filmed using SQ12 Camera

I got this SQ12 from Amazon:

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2018-10-12 - CMRS Touch Panels, continued

Category CMRS

This is a follow up on that proof-of-concept I made at CMRS about touch panels for the mainline.

I'd like to elaborate a few points, with some pros and cons, which I had been thinking about when I started the project. Upfront I want to make it clear I am not advocating for one solution or another. I am offering "food for thoughts", pros and cons, and matter of discussion. Some of the discussion involved industries or city names which are specific to CMRS’ layout. A map of it can be found in the link above.

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2018-10-01 - Cameras, OpenCV, and occupancy detectors

Category Train

A lot of my interests when it comes to model train layouts are all about automation. Automation can mean to make the trains move automatically but it can also mean to automate signaling -- displaying semaphores and search lights according to traffic on the layout. The common denominator for both is block occupancy detection, namely to know where trains are on the layout.

An early prototype of camera-based block detection

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2018-09-15 - NCE AIU-01 and Motion Sensor

Category NCE

The original design for the motion sensor was to use an ESP32 with an HC-SR501. The ESP32 would be used to send a sensor activation command to JMRI.

Since I was working on RTAC, it occured to me I could use it to drive a Digispark Tiny via a wired USB connection and the same sensor. Then RTAC could just manipulate a Conductor variable directly over the KV server connection. This has the advantage that it removes the requirement for wifi. One less dependency. Or does it?

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2018-09-02 - Digispark Tiny

Category Arduino

The Digispark Tiny is a probably the most basic and compact Arduino-like I’ve worked with. It’s about the size of an USB A plug. It is powered by an ATTiny85 and offers 1-5 I/Os depending on usage (typically 2-3).

(image source:

Kickstarter Date: 2014.

Example of the Digispark Tiny connected to an USB OTG with a PIR sensor:

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2018-05-20 - Signal quality in Advanced Tomato

Category Misc

I’ll just leave this here for those who use Advanced Tomato on their wifi routers: the “Quality (%)” column in the Device List is not a percentage at all. It’s just a delta from the client’s RSSI to the interface floor noise in dBm.

From, line 248:

2018-04-21 - Mobius Action Cam vs Runcam 2

Category Video

The latest video I did was an update of the full “cab ride” layout tour of the Randall Museum layout.

In the past I’ve used the same camera as for all my previous cab rides, a Mobius Action Cam. When I tried to use it after a year of inactivity, I realized the battery is dead and won’t hold a charge for more than 10 minutes. I can order a new battery, but maybe it was worth looking at what had changed in the domain in between. Let’s look at the Runcam 2.

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2018-01-21 - Turnouts Touch Panel for JMRI at CMRS

Category CMRS

Some members at the CMRS train club (the Carquinez Model Railroad Society, in Crockett, CA) desired to have large touch panels that members could use to toggle switches on the mainline. For testing, one of the members procured 32-inch touch panels and I wrote a quick experimental software to display the mainline on it and control turnouts based on touch.

The touch panels rely on the main JMRI server to trigger turnouts on the mainline.

This post documents my first prototype demonstration for this project. This was going to be an iterative process as I expected to incorporate feedback later. What I came up with is fairly easy to reuse for other layouts -- I’ve implemented something similar at Randall just after, so I’ll explain how it is implemented in the hope others want to use that or get inspired by it..

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2017-10-31 - NCE AIU and short trigger events

Category NCE

This is for Randall but I might just enjoy it myself too… The NCE AIU suffers from an obvious polling refresh rate issue: if an input doesn't trigger long enough, it will be easily missed.

Question is what would be the simplest circuitry possible to make an input trigger longer?

From the NCE AIU pdf:

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