Crossing Flashers

These ubiquitous details, seen here on my old White River & Northern IV, can be made more interesting if (1) they represent some of the more unusual styles, where multiple flashers faced in various directions, as they do in real life, and (2) reproduce the incandescent effect (as appropriate). Also see crossing gates for more insights.

As required, one of the signals must have a bell, such as the one below.

This video turned into one of my most popular, with tens of thousands of views.

Version 3

When it came time to install the signals on the Men at Work diorama, I replaced all of the LEDs. I did this because, first, I was disappointed that I could not create an incandescent effect owing to how the LEDs were originally wired; second, I felt that the LED pairs were spaced too far apart; and third, I wanted to correct how the lights on the gate arms flashed.

After trying several alternative methods to recreate the signals, I reverted back to very nearly the same techniques I'd used over two decades ago, right down to the types of LEDs and how they were assembled. The major cosmetic difference this time is that I added more flashers: originally the gantry signal only had the forward facing lights; now all of the flashers are properly arranged in pairs. Plus, I added another flasher to the rear pole at right angles to face the driveway across the street, as would be done in real life.

The electrical changes I made meant that I could not keep the signals removable, the way they were originally designed; however, this was actually okay: it allowed me to make a more precise gate mechanism to raise and lower the gates. Anyway, they'd be installed on a small diorama instead of a full-size layout, so they would not face the same construction and maintenance rigors.

Main Flashers. Once again I used T1-3/4 axial lead LEDs soldered together in pairs. This time, I pre-assembled the pairs to make it easier to solder them to the poles (below left), using jigs to hold them in place for soldering. Once I attached them to the poles, I added small brass washers for targets, and bits of shrink wrap for hoods, just as I'd originally done (below right). As I'm wont to say, "You can't argue with success."

Gate Arm LEDs. Although age and disease ordinarily conspire to prohibit me from doing things such as this, I found that the key to success was using pre-wired 0402 SMD LEDs. But if the leads are only going to be removed, what's the point? The point is the wire leads make handling these insanely small objects much easier. First, I remove the anode lead from the LED. Using the cathode lead as a handle, I position the LED against the gate arm, and briefly touch the contact point with a well-tinned soldering tip. Success comes either on the first try, or the fourth or fifth, but it does come. I also pause a bit after an unsuccessful attempt to allow the LED to fully cool.

When the LED is firmly attached, I remove the cathode lead and tin the end of the finest solenoid wire I've ever found—it's about the same thickness as human hair* (above left, compared to a ball point pen tip). I position the end of the wire across the top of the LED, and touch it with the iron tip—actually, I get a tiny bead of molten solder to float on the iron tip and touch the connection with the solder, as opposed to the iron itself. This can take quite a few tries, like ten to twelve or more. When the connection is made, I test the LED, and if it works, I bond the wire to the gate arm with CA to provide strain relief (above right). After all of the connections are made, I solder the wires to a tiny terminal board I fabricated for this purpose (below left), which I found necessary after many failed attempts to run the wires under the base. That's all the super-fine wires are meant to do: provide four super-flexible, nearly invisible electrical connections between the gate arms and terra firma (below right).

Note that I only rely on the gate arm itself to provide a common connection for the LEDs: that is, I don't rely on the fixed part of the gate to reliably conduct to the arm. It is necessary to make a connection to the arm itself, and run that wire to the terminal strip with the others. The lights would otherwise flicker as the gate moved, because pivot does not reliably maintain electrical contact.

The Flasher. This time around, I wired the LEDs conventionally—that is, the pairs are each wired individually. This allowed me to use a commercial flasher unit, and the one I chose (below) is readily available on eBay. They come from China, but I've never had a problem ordering them. I especially like these because they create the incandescent effect perfectly, making it an all-in-one device for just about any flasher effect.


*Where can one get such incredibly fine wire? If you have—or can obtain—an old stereo magnetic phono cartridge (non-working is fine), carefully break it open and you'll find two, or sometimes four, tiny coils (right). This is about the finest wire you can readily get, and at low to no cost. Beware, however: this wire is very likely much thinner than anything you've ever used, and working with it can bring you to the brink of madness. You'll need to exercise great care when soldering it—too much heat, and you'll melt the wire! Note that I only used it for the connections to the lights on the gate arms; any more than that and I'd be in a rubber room.

Gates

Animation of the gates on which these 20 LEDs are installed is covered separately.

Reference

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