Electrification of the couplings

Here, I will use Viessmann couplings which are in fact Profi Fleischmann modified by addition of two contacts. The interest is twofold: they remain compatible with the Profi, and they allow the reversal of a car without changing the polarity, because the contacts are superimposed, not juxtaposed.

Wiring of couplings

These couplings are orig­inally equipped with extra-flexible wires, but a little large to pass freely through the slot of the brass piece located above the drawbar. So, I change them for my usual 0.5 mm outer di­ameter wires. Attention: the de-soldering then the soldering of the wires re­quires to extract the contacts from the cou­pling, under penalty of melting it.

Coupling seen from below

Here is a view showing the connection of the 70 mm long wires on the strip. They are slightly glued to the strip with CA, leaving a lot of clearance. The blue, pos­itive, is connected to the upper contact of the coupling. The green is connected to the lower contact.

Connections between coupling and lighting strip

Note: the holder visible on this picture was finally not left in place, be­cause it could interfere with the body reposition­ing.

Tests

The BD car is first tested alone:

BD car alone test

At this moment, the lantern circuit has not yet been painted black…

Then the whole train:

Test of the whole train

But after just half an hour of operation, the train starts flashing while running, and then completely switches off. Diagnosis: fouling of strip / wheel contacts. So I have to modify the assembly so that the contact is made on the inner sides of the flanges, not on the tyres.

I make small parts from a brass strip 0.5 mm thick and 3 mm wide. The lower part is folded back on itself so as to obtain a thickness of 1 mm which will hold it in force in the housing of the bogie. The important dimension is the horizontal value of 3 mm. Indeed, if this dimension were larger, the part would conflict with the pivot supports.

Bogies with brass strip holders

The bronze strip is soldered on the short tongue; the latter must then be shorten­ed to the maximum. The connection wire will be connected on the long tongue af­ter installation. Soldering time must be as short as possible!

This time, the operation is correct. However, there are two minor disadvan­tages: first, it is neces­sary to remove the bogie rotational stops (arrows), into which the strips would bump. Then, the friction is a little stronger than before. But, again, for a short train, this is not a real trouble.

Bogie connections

In total, this installation required three days of work (not full time!), including the study, the taking of dimensions, drawing and etching circuits, assembly and testing… and taking photos !

Wait! It’s not over!

Finally, and contrary to what I said on the previous page, I anyway added an individual lighting control to each car. In fact, I gave up because I was starting to lack latching reeds that I could not find in the trade anymore. But as I found a mean to make these cheaply, I had no reason to deprive myself, especially since, because I control each car separately, there is no need of an extra contact on the couplings.

The principle is very simple: the couplings transmit the voltage rectified on board of the van, and the particular line to each car is supplied from the “train line” by a reed switch. That’s all!

Click the image to get a closer view on the reed switch.

Placement on the lighting strip

The reed switch is positioned above the toilet whose aerator will serve as a reference for the actuation.