My problem is that I am using 12 - 14 V bulbs inside buildings, but there are certain buildings which I have to add lampposts and hanging street lamps, and since they will be attached to the same building that already has lights in, I thought to connect the 6.5 Volts lamps to the wiring of the 12 - 14 Volts bulbs, but again, since the small lamps are almost half the voltage I need some reduction in voltage, and I cannot use other kind of bulbs or LEDs. The lamps I'm using have a buld approx 1.5mm dia. with 4 mm lenght, these are the smallest bulbs (lights ) I came across, so I have to stick with them.
My only chance is either find a solution through electronics, which has to be something simple that fits in small houses, or I have to start double wiring every building I have for 12 - 14V and 6.5V, which willt ake me double the time and material.