A show loading in next week was asking how they would be able to have practicals located on their turntable. The only affordable thing I could think of was some sort of battery powered setup. Any ideas?
you can also get some power transfering brushes and circular pads, but for a turn table I would tend to want to keep it low voltage. One or two circuits would not be that expensive. Don't run the returnthru the frame as some companies do however. Bad practice even if low voltage.
Look if possible at how a Mars Light such as from Tripp light works, - them old cop gumball lights, or other revolving lamps. Same concept. Otherwise shop trouble lights or self winding extension cords have much the same principals. All just on a smaller turret ring as it were. Grainger or McMaster might have what you need. Too bad Stagecraft is off line, someone there would otherwise have a source.
Probably the most cost-effective method would be to run a feeder and a DMXline up through the pivot, with local "shoebox" dimmers on the turntable. It's important to limit the number of cables - you don't want several channels' worth of individual power coming up through there. Also important is to limit the number of turns in one direction and remember to unwind. If the turntable runs continuously in one direction, you'll need a brush/slip-ring assembly, but if it just goes one or two turns in one direction, then can be run one or two turns in the other, cables through the pivot will do nicely.
As for batteries, mainly I think most people are not very interested in them is the pain in the rear of charging batteries up after productions and in the case of lead acid ones, should they drain completely you can’t recharge them again. A few 12v Lead Acid batteries otherwise should be fine for use with MR-16 lamps. Look at the ah or Amp Hours to figure out what is best for what you need. I wold probably go double the max length of use to ensure they don’t get too dim during the scene. In line I would also install a switch so you can turn the thing off. At one point I think I counted something like 30 exit lights rigged for hanging on pole and drape for display booths for conventions. Seemed like every time someone had a booth they would buy another set of them. Anyway, such things would be turned off during the show and go to battery backup. Than be put into the road box with the lamp still on. Cost a few hundred dollars to get new batteries for all of them again afterwards. Don’t let them drain, after that remember it’s the amperage that can be given off for that many hours so the wattage of the lamp will also play a factor. Such Lead Acid batteries are commonly available in say a 1.1/2" x 5" x 3" size thus would easily be installed into the frame of a platform for hiding. Drill holes thru the frame for the lamp. Simple enough. Juno makes some very nice spot and wash fixtures along with other brands. You can easily remove the track lightingplug and just wire the fixture to the battery in bolting the yoke to the platform. Decently small and intense.