Electrical contact idea

[FJ and G]

During last week’s topic I had on liftout sections, I failed to mention an idea that was stirring in my head. I floated the idea on the MR forum and would like to include it here because a number of you have or are considering liftout sections. The same principals would work on liftdown sections, such as bridges that flip down to allow you to gain access to the center of a room. It could even be used to connect modules:

Instead of placing a plug that you have to connect and disconnect each time you use a liftout section (usually for access purposes), has anyone tried using simple brass contacts at the bottom of the liftout section where it joins the permanent sections? The weight of the liftout section would simply rest on contacts and automatically form a circuit each time the liftout section is inserted.

Gordon suggested the use of springs to ensure contact.

Then, ndbprr replied:

“Brass oxide will not conduct current as those of us old enough to have had brass track are aware. I would use something else for the material such as Phosphore bronze or silverplated contacts and a pin that could be polished. I would also make the strips spring loaded so there is a set distance that the modules slide together but a shorter distance for the pin to make contact with the metal strip. That way it self adjusts rather than be a fixed distance. One thing to watch for is the amount of contact area between the two. Making the pin come to a point would be the equivalent of a fine wire, which could severely limit power distribution. If the strips were supported like a diving board and could flex down it could be feasible and you could have as many side by side as you needed.”

Dave Vergun

[Anonymous]

It seems to me that you're essentially talking about enlarging a "card edge connector" from a PC board. You could use something like that, but the ideas you've gotten so far sound sufficient.

The point about contact surface & resistance is extremely important, since we get pretty large currents flowing in O gauge. You want the most contact area you can get to minimize power loss across the connection.

Tony

[cnw1995]

Dave, this idea rang a bell - I regularly pick up some British railway modeling magazines - and given the emphasis on operating display layouts on that side of the pond, there are some similar ideas - almost all are for conventional power connections and in DC. After digging through a few 'how-to' articles - I notice there are myriad different ways of connecting up modules with all sort of electrical connections including just plain contacts.

[lionelsoni]

I open about the last inch of the tubular rail of the bridge to a slightly flared-out inverted U shape, but with the same width at the top as the original railhead. This fits over the exposed pins of the stationary track. I cantilever the ends of the bridge rails by a few inches and bend them very slightly down, so that they press firmly against those track pins but straighten out under the weight of the bridge.