Having done many turntables with
power in the center, the first thing you should do is to plan for that BEFORE you
build the
revolve. Unfortunately yours is already built, so that limits your options. Here are various methods to run
power to a
revolve and others have already listed several of them. I'll try to make a somewhat comprehensive list and explain them. Some various methods are:
1. Simply run an extension
cord. Must be unplugged when the
unit revolves and re plugged when it stops.
2. Use a small generator or battery
power and inverters to provide AC if necessary. Use wireless if needed, to
send or receive signals to units not on the
turntable. Note, even the quietest of generators is likely to be far too noisy for any event other than a high
decibel music genera, game shows and similar. You said the set up is in the center of a
roller rink???? If this is for DJ music during skating sessions, noise is might not be such an issue.
3.
Drop power from directly above and as close to the center as possible. Number of rotations limited by the cable bundle size and the height the cable is dropped. Must be rewound or unplugged and untwisted as needed.
Now, methods that need to be considered
before the
revolve is built.
4. Simple hollow shaft. make you central pivot
pin out of pipe or mechanical tube at least 4" diameter or more. Mount you pivot flange bearing so there is ample room below it to run the cables under the bearing and up through the hollow pivot. All
wire/cable is hidden but like #3 above, the number of turns is limited by the size of the cable bundle and how much flex/slack you can work in at the start. Of course it must be reset/rewound as needed.
5. Use a
slip ring, either commercial or shop built. There are two primary kinds of Slip rings and a
one-off kind. Of course the cost is determined by the number of contacts you need, the amperage needed, whether the contacts are for
power or data, whether a commercial product or shop built. All three types need to be designed and engineered into the design and construction of the
revolve, the first two also involve the design and construction of the central pivot. NOTE: for shop built units you need to have a commercial grade machine shop at your disposal
AND you must have
highly skilled electricians and craftsmen on staff
AND if the design and plans are not from a commercial source, you
MUST have a
LICENSED Electrician approve the design. This is not a code or
NEC or
OSHA requirement, it is simply the only
RIGHT, non Darwin Syndrome way to go about it. Experience has shown that data and signal circuits need to be constructed out of higher grade contacts and to a greater degree of precission in reguard to constant pressure, correct pressure and degree of smoothness of contact when running. All contacts
MUST be kept clean and free of dust and debris.
.....A. Vertical stack. This is the most common. The contacts are are arranged in a vertical stack of bands. this can work well if you have a lot of space under your
revolve or a void like a
trap room below. Vertical stacks require a relatively large amount of vertical space but the diameter is relatively small, 6" to 14" for an average 3-6
circuit 30 amp
unit. Data only or fewer circuits can be smaller, units that require liquid commutation as well can be larger. You can figure a minimum of 4" plus at least 3/4" per 110vax or 220vac contact. Data or signal contacts usually require less space but vary widely between manufacturers.
.....B.
Pancake style. This is a
flat,
concentric ring style that require only 4" to 6" of vertical space to operate. The trade off is of course the diameter. While a vertical stack may be only 6" to 14" in diameter, a
pancake type can easily reach 4'-0" diameter. The Largest I have built was for a 36', steel frame
revolve designed for Wildwood
Park For the Performing Arts in Little Rock, Ar. circa 1994, and still in use today. It was 4'-6" in diameter and required only 4.5" of vertical height. Although I used commercially built, high amperage brushes, the most expensive part was the 5'-0" x 5'-0" x1/16" thick copper plate used to manufacture the concentric rings for the circuits. There were ten 20 amp circuits, one 50 amp
circuit and 3 data circuits. Each
circuit required a separate
neutral so there were 20 rings 3/4" wide, 2 rings 1.25" wide and 6 at .5" wide. The width includes the insulated separator between rings.
....C. Shop built wiper type
slip ring. There have been several types of these outlined in the
USITT Tech Expo over the years, both for revolves and for straight
line wagons. If you need to find out about these, check the
USITT archives or get some one with the Tech Expo publication from the appropriate year to
send you a copy. IIRC, there have(has) also been a similar article(s) in the Yale Tech Briefs, If you can acquire the correct issue.
) Does anyone recommend any brands?
