Tape contact for turning on a trackside accessory
For the passing-by of a train to turn on a crossing gate, a gateman, a signal, etc., an electrical contact needs to be made when the train passes by. Such a "triggering" contact can be established by wheel-axle-wheel making contact (A) from one outside rail connected to "electrical Common" to (B) an opposite outside rail which is electrically insulated from the rest of the track system and is connected to the crossing gate, the signal, etc.A few years ago I had installed some Gargraves track on my layout, without having had the foresight to cut and insulate some sections of outside rail at strategic locations for train-detection purposes. (In particular, I lacked contacts for making the Gargraves switchtracks to work with a "non-derailing" function.) To remedy this problem without having to remove the track from the table (for cutting and insulating), I left the track in place and added to it some "tape-contacts". Since I am not a model craftsman, what I did (and describe below) is somewhat crude aesthetically but still very effective electrically. The idea itself is good, and those of you who have better skills, tools, and materials could do this in a better way.
The basic idea is (1) to insulate the surface of one of the outside rails with Scotch tape, (2) to put a strip of 3M Aluminum tape ( http://www.3m.com/product/info...minum-Foil-Tape.html) over the top of it so that the passing wheels contact it, and (3) to connect a wire from the tape to the trackside accessory circuit. (Although copper tape http://www.gardeners.com/Coppe...-994,default,pd.html would be a better conductor, I prefer the color of the aluminum.)
For anchoring the tape on the outside of the rail and elevating it to the top of the rail,, I cut a piece of pine molding (0.25" x 0.5", beveled on one side) to a length of 1.5" (to match the width of the aluminum tape). I wrapped the tape from under the molding, over its top, and then over the rail. On the inside of the rail, I pushed the tape down to the top of the wooden ties, and anchored it in place there with 1.5" length of a stick from an ice-cream bar. I used double-sided Scotch tape to tack things in place temporarily, and then I screwed the molding and the ice-cream stick to the table in order to hold the tape firmly.
Attachment #1 shows the aluminum tape and the piece of molding.
Attachment #2 shows (a) the "Magic" Scotch tape used for insulating, (b) the double-sided Scotch tape used for tacking, (c) the 1.5" lengths of molding and of ice-cream bar (painted black), (d) the screws, and (e) the connection wire.
Attachment #3 shows the tape installed.
Attachment #4 shows how black paper can be used to conceal some of the shininess of this set-up.
I hope this idea may be helpful to those who may face the same kind of problem as I did.
/Ralph Platz
