Block Signal - 3-Aspect

Model Railroader Electronics and DCC
1

I am thinking about a 3-aspect block signal (green/yellow/red) to indicate PROCEED/PROCEED WITH CAUTION/STOP.

I would operate it “manually”, as opposed to occupancy detection circuitry, by simply throwing a switch to each of the three positions.

Would some type of ON/ON/ON switch work for this approach?

Would it be a DPDT, SPDT, SPST?

Any help or advice would be appreciated.

Rich

2

Rich,

I have a handful of signals on my layout that are “animated” by the Logicrail Signal Animator.

https://www.logicrailtech.com/

For what you want to do the best solution would be a four position rotary switch (one for off if you want the signal dark) but for realism you would have to switch the signal every time the engine passes the signal. You could use a latching pushbutton switch (like a blender uses) as well but they are trickier to find. Electronics surplus joints are your best bet here.

That is where the beauty of the signal animator comes in. MSRP is $20 but I have found them for less. The IR model is nice but the photocell works pretty well if your ambient light is pretty constant.

https://www.logicrailtech.com/sa_inst.pdf

Depending on the type of signal you are using you have to get the right model of Signal Animator.

I enjoy watching the signal aspects change automatically and that, to me, is worth the cost of the Animator…

Have fun, Ed

3

Ed, thanks for the quick reply.

One signal that I am considering is the BLMA 3-aspect target signal.

I have thought about the Logic Rail Technologies Signal Animator.

Would it be the SA-1?

Rich

4

Clear, approach, stop /stop and proceed/restricting.

Yellow doesn’t mean proceed with caution, it means slow down and proceed prepared to stop at the next signal.

Depends on what you are doing. Normally a block signal system is several signals that are tied together. When a train goes by a clear signal it turns to stop/stop and proceed. The next signal behind the train displays approach. When the train passes the next signal the approach signal clears and the stop/stop and proceed signal changes to approach. All automatically, the dispatcher doesn’t control those signals.

The question is what are you trying to do with the signals, what are you trying to simulate? A block signal system, a manual block signal system, centralized traffic control, an interlocking?

Old school would be a rotary switch that would throw the switches associated with the signal too.

5

Dave, thanks for those informative comments.

Eventually, the plan would be to establish a more sophisticated block signal system.

But, initially, it would be nothing more than a manually operated system of turning the signal from red to yellow to green and vice versa.

Rich

6

Rich

If you are talking about the color light signal, three separate “lenses” then, yes, you want the SA-1 for common anode wiring which BMLA uses.

I have some of the BLMA searchlight signal heads (their mast structures are too modern for my layout) these have the “true yellow” which is beautiful (3 separate LEDs in there!!) this would use the SA-1 as well.

I only want to see the signals change. I’m not concerned with the distant signals, etc (they would most probably face the wall, anyway) and a truly realistic signal system generally is impractical for our little layouts anyway.

Some of my SAs are wired so that if a turnout is thrown against them they go to red. A feature you can easily wire into the SA board. Has a nice effect.

https://www.logicrailtech.com/sa_inst_supplement5.pdf

Shown in the above document. (Even though these instructions use a two head signal, I use a three aspect signal anyway and it works fine.)

High greens! Ed

7

Yes, I am talking about the signals with three separate lenses, green, yellow, and red. My preference is for hooded block signals or searchlight signals.

Rich

8

It depends on “where” the yellow is, but yeah, this.

Single-headed mast → Yellow (implied over red/red) means exactly what dehusman said.

Double-/ Triple-Headed mast → There are a lot …

Also, your signals would be displaying “Absolute Stop” rather than “Stop and Proceed”, as you’re emulating blocks.

9

Thanks, Dan.

I think that the key consideration for me at this point is how to trigger that yellow light. My experience to date is solely with bi-polar LEDs on the control panels and Tortoise driven red/green signals (dwarfs and searchlights). For that, I rely on DPDT toggle switches. With that third light, yellow, I need to figure out the alternatives to lighting it, that is, flipping a switch manually versus electronic occupancy detection.

Rich

10

Fliiping switches is cheap - they do make switches with more than 2 poles, so you get 3 or more options. However - you went DCC to get away from flipping switches. Detection and control circuits are more expensive than switches, but probbaly the simplest way to just have signals change automatically as the trains roll past, and it a somewhat protypical manner, is to use the Signal Animator and detectors.

To get a truly realistic system, you need to tie in block detection, turnout position, and logic to link it all together. That’s where it starts getting complicated and expensive.

–Randy

11

Let’s say that even in the face of consistent advice to set up detection and control circuits, I decide initially to simply set up a switch that I can throw manually.

Any advice on which specific switch to select for an HO scale DCC layout where signals and LEDs are powered by DC power packs.

Rich

12

Well, if you want stupid-simple, then just use simple SPST toggle switches to turn on/off the colors individually (so, as they’re three LEDs, you could have red/yellow/green lit at the same time … or all off). They just need to be able to handle the ~12 or 16 VDC that you’re using.

Otherwise, a rotary switch will “lock out” the possibility of having multiple colors lit.

Are you doing this for multiple blocks, or just a single “block” because you want to have a signal?

13

Been there, done that, got the switches that you need.

LION planned to do that, but on a subway layout with hundreds of signals it got just too complicated. I only adjusted the signals for a photo shoot, and even then I had to figure out what switch went with each signal.

Here is a row of such switches with their associated wires.

OK, I really wasn’t kidding about having too many of them to keep track of… You can see the bus wire, with a 1K ohm resistor going to each switch and the bowl of spaghetti that enervates the signals.

And here they are in the store…

But Wait! There is more! I have many of them (new) left over that I will not be using. An email to the LION might get some sent out to you. How many do you need? [lion (at) broadwaylion (dot) com]

ROAR

14

Radio Shack even still has them - for too much money, but they do have them

http://www.radioshack.com/product/index.jsp?productId=20198426&CID=ip%3ASEM%3ARSO%3AGoogle%3Arotary_switch_radio-shack&stop_mobi=yes&utm_source=google&utm_campaign=RSO_SRC_EN_NCA_TM_P_Hobby_Do_It_Yourself&gclid=CMLni-XsqcECFTMQ7AodGWMABg&utm_medium=ppc&gclsrc=aw.ds

You only need 3 positions and 1 pole of it. Although you could use the second pole to control the other signal at th other end of the block, or the 2 aspect signal you’d put ont he diverging track at a siding.

Common one side of each LED, this goes to the appropriate terminal on the power supply. The other side of each LED, via resistor, goes to one of the poles of the roatary switch. The common on the rotary switch goes to the other side of the power supply.

–Randy

15

LION, thanks for that lead. I am intrigued by the 3-position slider switch.

And, I appreciate your most kind offer.

Let me think about that and get back to you.

Rich

16

Randy, that is a pretty cool switch as well. Gotta give that some thought.

Rich