I have been slowly installing IR sensors on my layout to enable computer control - key word "slowly". Even though my sensor has only a couple of components and is quite inexpensive, installation has turned out to be so tedious to the point where I am beginning to look at alternatives.
Are any of you on this board using reed switches to detect trains and if so what would you recommend? My requirements are quite simply to detect whether a train has passed a certain spot. I do not need occupancy detection (which I could do with current-draw sensors like the Digitrax BDL 168).
Anand
Slowly building a layout since 2007!
I've recently installed some magnetic reed switches from Miniatronics. I have subways on my layout, and I'm adding a new subway station which will effectively function as staging. Once the layout is further along, these tracks will be hidden. As such, mine are really "occupancy detectors" rather than "train passed" detectors.
These reed switches cost $9 for a package of 5 magnets and 5 switches for HO-scale. The same company makes a smaller set for N-scale. From what I can tell, the magnets are well-matched to the switches, although I'm sure you could buy more magnets from another source and they would work. I've glued the magnets directly to the frame of the subway cars.
These are single-pole, single-throw switches. They are momentary contact, and are only active when the magnet is very close. I have only an inch or two of travel between the point where the switch closes and where it opens again. Again, because the train is stopped at a more-or-less fixed point on the siding, this is not a problem in my application.
It takes an iron man to play with a toy iron horse.
Thanks for the pointer. I took a look at the Miniatronics site and it looks like it might get the job done. I have several questions:
Did you install the reed switches longitudinally along the tracks or perpendicular like ties? I guess this might depend on the length of the reed
Would you possibly know the difference in size between the N and HO scale switches? Would it make sense to use the N scale switches in HO (my scale)
Finally: Some of my reed switches might have to be installed on a curve (24" radius). Are the reed switches sufficiently sensitive that they will activate even if the magnet is a bit off the center line?
Thanks in advance
Did you install the reed switches longitudinally along the tracks or perpendicular like ties? I guess this might depend on the length of the reed.
I installed them longitudinally. They are about 3/4 of an inch long, so you really can't put them crosswise.
The N-scale ones look to be smaller, with the biggest difference being the size of the magnets. I'm guessing here, but I think you really want the HO ones for HO. The detection range is pretty small, and I think they can use the smaller magnets for N because the floor of the cars is closer to the ties. The N-scale ones are a bit more expensive, as I recall.
I don't think that would be a problem. If centering the switches between the rails results in reduced sensitivity, though, you could mount them a bit closer to the inside rail.
Do reed switches need a constant pull from a magnate or is there a constant contact reed switch?
I ask because I would like to operate some lights for buildings by using a reed switch and a magnetic wand.
Dennis Blank Jr.
CEO,COO,CFO,CMO,Bossman,Slavedriver,Engineer,Trackforeman,Grunt. Birdsboro & Reading Railroad
You can get what is called a "latching reed switch." The Miniatronics ones are not latching, and only remain closed while the magnet is nearby. For some reason, latching reed switches seem to be much more expensive. You will find these in some passenger cars to turn on and off the lights with a "magic wand." I think some engine manufacturers installed them and gave you a magic wand that would reset your decoder to its defaults. (In an environment like a layout, which is using magnets for things like uncoupling, I would think this could be quite dangerous.)
An OT question for you? How on earth do you remember your user name? Just curious.
Mister Beasley (Or other knowledgeable person)
I'm trying to figure out how to report a reed switch activation to LocoNet.
Do you know if a Digitrax BDL168 will report as 'occupied' when a voltage controlled by a reed switch is placed across Zone A and DS1 rather than connecting the rail wires? If so what voltage should be used? AC or DC?
Thanks,
Dave
From Mt Pleasant, Utah, the home of the Hill Valley and Thistle Railroad where the Buffalo still roam and a Droid runs the trains
rxanandI have been slowly installing IR sensors on my layout to enable computer control - key word "slowly". Even though my sensor has only a couple of components and is quite inexpensive, installation has turned out to be so tedious to the point where I am beginning to look at alternatives. Are any of you on this board using reed switches to detect trains and if so what would you recommend? My requirements are quite simply to detect whether a train has passed a certain spot. I do not need occupancy detection (which I could do with current-draw sensors like the Digitrax BDL 168). Anand
..... Bob
Beam me up, Scotty, there's no intelligent life down here. (Captain Kirk)
I reject your reality and substitute my own. (Adam Savage)
Resistance is not futile--it is voltage divided by current.
Bob's informative reply reminded me to post a follow up to the original question.
While studying the various kinds of reed switches that are available, I was looking through an electronics magazine and came across a new kind of reed switch from a German company, Meder Electronic, called a "cylindrical reed sensor". This little gadget is a very sensitive reed switch but is packaged somewhat like a transistor. It requires only one discrete 1/8" hole between the ties in the track. It has worked so well, I ordered a big batch of them form Mouser and have been busy installing them all over my layout.
I have a detailed posting about this sensor on my blog. I am in the process of writing a survey of the various train sensing technologies that are available and hope to have more postings up in the near future.