![Does this make sense? :scratchhead:](./images/smilies/headscratch.gif)
The holder from one of my original lights, sadly beyond repair, is shown below.
![Image](http://i284.photobucket.com/albums/ll28/RealEstate99/Dexta/P3070397.jpg)
The bulb holder sits in a rubber mount inside the light and so is insulated from the body of the light. Note that the original bulb has a single filament, rated at 12V/6W, and two contacts at the bottom (see RH bulb in photo below). Thus one of the contacts, with the black/white wire, is attached to the surface of the tractor's wing serving as Ground.
Unlike modern bulbs, the metal body of the bulb does not form part of the circuit and is insulated from both contacts. Another point is that the two nubs on the side of the bulb are the same distance from the base, meaning that the bulb can be fitted in two positions 180degs apart.
The photo below shows the bulb from the repro sidelight (left) and original bulb (right):
![Image](http://i284.photobucket.com/albums/ll28/RealEstate99/Dexta/P3070395.jpg)
Both bulbs have the same sized base, so both will physically fit in repro or original holders.
But the repro metal bulb holder is not insulated from the body of the light. Indeed the holder is pressed into the body of the light and is thus at Ground.
The repro bulb has two filaments rated at 21W/6W. Interestingly both filaments are attached to one of three wire posts inside the bulb. The repro bulb has two contacts at the bottom. It also has two nubs but, unlike most modern bulbs, both are the same distance from the base of the bulb meaning that the bulb can be fitted in two positions.
Question:
Why does the repro bulb have two filaments?
Do I ignore the 21W filament (which seems much too bright for a sidelight) and use just the 6W filament? Since the ground is via the metal body of the bulb, the other wire can be cut off and removed? Or is the 2nd filament in the repro bulb for a brake light, in case we chose to fit our dexta with brake lights?
Alternatively I could retain both wires in the repro holder, but fit an old style bulb having a single filament and insulated metal body. Note that if both wires are retained and a repro bulb is fitted, one of the two filaments will light up depending which position the bulb is fitted.
Has anyone wired up their repro lights, if so how?
Can the old style bulbs with insulated metal body be easily sourced?
TIA
![Wink :wink:](./images/smilies/icon_wink.gif)