The picture in the article appears to be of a Marx signal, whose terminals are arranged in a different order. For the 154, connect terminal 1 to the center rail (or to a fixed accessory voltage). Connect terminals 2 and 3 to the two pieces of insulated outside rail.
You may already know it, but I think that the article should have warned you that this technique will flash the crossing signal's lights in an irregular pattern.
Bob Nelson
lionelsoni wrote: You may already know it, but I think that the article should have warned you that this technique will flash the crossing signal's lights in an irregular pattern.
Bob, I'm a few weeks away from putting my layout together (all conventional) and am planning to use the insulated track method in lieu of contactors. Is there a way to do this with a 154 crossing signal so that it operates correctly? If not, I do have a 154C contactor.
Unfortunately, the 154C does pretty much the same thing as the technique described in the article, and will not produce a prototypical regular alternating flash. To get that, you pretty much need an electronic flasher circuit, activated by a longer isolated control rail.
Here's a stab I took years ago at the simplest possible electronic flasher. I tacked one together; and it seemed to work fine. I don't have any way to show you a schematic; but I'll try to describe the circuit. I will put Radio Shack stock numbers in parentheses. Get a bridge rectifier (276-1152). Connect one of the two terminals on each side of the "+" marking to the accessory voltage of the transformer or to the center rail of the track. Connect the rectifier terminal on the other side of the "+" to an insulated running rail. Connect the "+" terminal of the rectifier to the positive terminal of a 1000-microfarad capacitor (272-1019 or 272-1047) and the rectifier terminal opposite the "+" to the negative terminal of the capacitor. Call the positive capacitor terminal V+ and the negative V- from here on. Connect the crossing-signal common, terminal 1, to V+. Connect the emitters, marked "E", of two 2N3904 transistors (276-2016) to V-. Connect one crossing-signal lamp, terminal 2, to the collector, marked "C" of one transistor, the other lamp, terminal 3, to the collector of the other transistor. Connect a 3300-ohm resistor (271-1122) between V+ and the base, marked "B", of one transistor. Do the same with another resistor for the other transistor. Connect the positive terminal of another 1000-microfarad capacitor (272-1019 or 272-1047) to the collector of one transistor and the negative terminal to the base of the other transistor. Then do the same, switching the roles of the two transistors. If the circuit flashes too slowly for you, decrease the capacitance of the last two capacitors described; increase capacitance to slow it down. An easy way to cut the speed in half is to put another 1000-microfarad capacitor in parallel with each of the existing capacitors.
Bob-
That last bit of information is too technical for me. The first article you posted is what I needed to know. I got it working using your technique, just as long as them lights flash is fine on my 1st layout. Thanks!
Doug Murphy 'We few, we happy few, we band of brothers...' Henry V.
Thanks, Doug.
Clinton, I'm glad you got it working. I posted that circuit description for Rich, who seemed to want a better behaved flash.
As a child in the 1950's I had a 154 crossing flasher and it bothered me that it didn't flash like the real thing. So when I started my postwar layout as an adult, I found an electronic circuit online that would flash the lamps properly. The circuit is fairly easy to make. I have three of the circuits in operation on my layout and they work great.
EASY FLASHER CIRCUIT
http://www.mrollins.com/flash3.html
I am presently working on a way to merge my present layout with my Soldering Final Project from a school I was sent to last winter. It is a 9v multivibrator circuit with two red LEDs. (In short, it is a circuit that alternates which LED is lit, much like a crossing signal.
What my plan is to use a spring return relay attached to an insulated section of track, the relay will be attached to the DC power supply for the flasher circuit, when the flasher circuit is energized, it will make the signal lights flash.
I have been thinking of making a primary multivibrator chassis that would energize when at least one circuit is energized, to provide a common flasher path, making overall wiring simpler, and making troubleshooting a lot easier, not to mention that costs would be less.
I am pretty sure that this is a tad bit more techinical than desired, when I get around to making the circuit work, I would be glad to share drawings and instructions.
James
So many scales, so many trains, so little time.....
Dsmith:
Can you explain how output 1 & output 2 work? Do you just connect one leed to that point in the circuit? What is the other "side "of the circuit for each of those lights which flash? I take it that the pink and black coming in from the right side are the16VAC in. Do you have a picture? What is the flash rate? Can you vary the flash rate by changing the values on the resistors or what?
Sorry for so many questions but this looks pretty cool. Thanks
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