Cereal wagons usually travel on block trains. It is therefore necessary to equip the last wagon with end-of-convoy lights. I will explain briefly how I realized these lights. A more detailed page can be found in the REE hopper article.
I chose a flat wall model because it is easy to disassemble.
The equipment of the wagon with brass bearings is facilitated by the fact that the bogies can be completely disassembled, which makes it possible to easily dig the axle boxes. Some older models even have insulated half-axles with non-insulated wheels, which is ideal for the current pickup.
This is not the case for the model I plan to equip. I have therefore to swap insulated wheels for non-insulated wheels. See the article on the Nord Rapide coaches.
These are REE lamps that I have equipped with SMD LEDs. They are glued, after scraping the paint on the back, on the lamp holders opposite the footbridge. The wires go directly down under the buffer beam and then run along the edge of the chassis. Be careful to pass under the buffers that are mobile and could catch the wires.
The brass bearings are connected in pairs by a strand of wire soldered to a flexible wire. The wires coming from the lamps and those of the bogies pass through a hole drilled into the hopper and are soldered to the control circuit equipped with a bistable reed switch allowing the lamps to be switched on and off.
The (220 µF) capacitor is mounted under the PCB. It is stuck with thick double-sided adhesive on the single ballast plate that I left in place. This arrangement allows the reed switch to be high enough to be operated without difficulty by a magnet placed above the wagon.
One can see that wires (red and black) leave on both sides. Indeed, I have equipped the two bogies with current pickup. But it was actually not necessary, only one would have been sufficient.
See this PDF for the diagram and etching mask of the PCB.
Vertical illumination is unforgiving for the junction between the body and the roof!