I have made several portable "light boxes" for a specific application in our manufacturing plant. What this consists of is 12 volt 35 watt automotive lamps mounted in a row in a box. I have done several with using transformers to drop from 120 volts to 12 volts. Also I have done several using a total of 10 lamps wired in series to 120 volts. (120 volts divided by 10 = 12volts. this works great except when a lamps burns out they all go out but that is not a problem for us.
I need to build one with 5 - 12 volt 35 watt lamps. Rather then using a transformer to drop down to 12 volts I would like to use my series method. Of course that would give each lamp 24 volts which would not work.
My question is, can I put resisters of the proper resistance in series with the lamps to get down to 12 volts? If so, how do I size them for wattage? I know how to size them for resistance, but I know they also have a watt rating and I would need to know how to size them that way
