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I have a question that while on the surface it may seem off-topic but this is the only forum that I feel I can get a knowledgeable answer. I am a Digitrax user and as funds become available, I am setting up a detection system using the SE8c for the signaling and the BDL168 for detection.

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Now for the off-topic part of my question. As I accumulate funds for signaling and detection, I am working on other aspects of the railroad…at the present time, I am working on ballasting the track. There is not a single type of ballast product that correctly models the ballast on the railroad I am modeling so I have been blending three different types. One is from the company Superior Scenics. After blending about half a quart of ballast yesterday evening with this product in it, I discovered that Superior Scenic ballast has some MAGNETIC rock in it, probably iron. I have yet to lay any of this ballast down but I am now concerned that with a magnetic ballast, detection and/or signaling might adversely be affected. I know fully well that magnetic particles, should they get into a motor will destroy it and I am also aware that any tank mounted speakers could pick it up and the sound would be detrimentally affected. Does anyone know, or have experience with, detection/signaling over trackage with a ballast that contains magnetic particles/granules?

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Thank you for any and all comments,

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Jim Shellhaas

Westfield, IN

The BDL168 uses current flow to detect occupancy so will not be affected by any magnetic material in your ballast.? However, your other concerns about the magnetic properties need to be addressed for reliable operation.

Maybe it is worthwhile to scrap the Superior Scenic ballast and find a substitute - cost a little more no but save forever future headaches.
--
Dale Gloer
Layout Supervisor, Southern Alberta Model Railway Club

Jim: What happens when you spread some ballast and run a magnet over it resting a few mm above the tops of the rails? I ask because magnetic field strengths vary greatly and there will be some combination of distance and magnet strength that the ballast will not jump up to the magnet. Well designed products that use magnets, like speakers and motors, maximize the efficiency of their magnets by minimizing magnetic leakage which makes external fields smaller by design. So strong magnets don't necessarily mean high external fields. I would do some experimenting before assuming that there is a concern in practice.

But if there is a concern can you not find some ballast that is non-magnetic such as by mixing powdered pigment (art supplies or dry weathering product) with aggregate that is the right shape and size?

Jan

Stick the two probes of an ohm meter into the jar.? Compress the ballast.? If you get any reading other than infinite I would discard the idea of using that ballast.? As far as I know, only ferrous materials are attracted to magnets.? Ferrous materials can conduct electricity and give false detections.? Personally, I wouldn't touch it!
Dave...

I've found enough motors and speakers 'clouded' by magnetic particles to say
'avoid'! On the cone of a speaker, it kills the sounds by adding weight to
the moving parts. For motors, it tends to find a way to sneak in and wear
something. On the outside it may affect the magnetic field. I'd say the
possible issues make it something to use away from the tracks.

-Ken Cameron, Member JMRI Dev Team
www.jmri.org
www.fingerlakeslivesteamers.org
www.cnymod.org
www.syracusemodelrr.org

Being a cheapskate, ballast that came anywhere near what I wanted happened to be the local lake beach sand, sifted, but as I discovered full of metal particles. My solution at the time was to run the proposed ballast over a very large speaker magnet numerous times, this resulted in a material loss of about 60% ( lightened the colour to ) of metal particles.? I still however made sure ballast did not touch underside of rails and of course was glued in place.? I did have some less than zero readings but that all disappeared once white glue was totally dry. I have had NO issues regarding any false readings even though they are in a harsh environment. ( Mobile train show display )? PS? I did go over track with magnet after dry to be sure and my detectors are set at 20k ohm operation. John.