SparkySteve Posted April 13, 2005 Share Posted April 13, 2005 hi all... little problem to pick your brains with. We're looking at using a rotating piece of scenery - like a propeller or windwill type thing - and using festoons on the 'blades' to give it a good ole cheesy look! The problem being we're not sure how to get power to them... obviously with a spinning motion any cables going out to the 'blades' are going to end up twisted and messy... is there any 'standard' way of supplying power to such a piece of scenery? thanks in advance, Steve Link to comment Share on other sites More sharing options...
Brian Posted April 13, 2005 Share Posted April 13, 2005 The usual way to do this is with 'slip rings'. A pair of contacts, concentric with the shaft, on the rotating part and a pair of contacts on the fixed part which touch each other but can 'slip' over each other while maintinaing electrical contact. You can buy slip ring assemblies as complete units but they are relatively expensive. Could you not use LEDs and have batteries fixed to the rotating part? Link to comment Share on other sites More sharing options...
Tomo Posted April 13, 2005 Share Posted April 13, 2005 I'd suggest extra-low-voltage parts for this purpose - LEDs or low-voltage fixtures like 12v birdies. As Brian said, the usual method is slip-rings. The cheapest way to get hold of these is to go to a scrapyard and buy some old windscreen wiper motors. Open up the gearbox, and inside you'll find a horizontal set of sliprings - one is full, the other two are broken but overlap, so one unit gives you 1 channel of connection.The rating on these slip rings is around 20A at 12vdc (power is sent to the motor through these), so you shouldn't have any real problems with festoons. Get as many as you need dimmer channels, put the transformers outside, run the extra-low-volt lines into the sliprings and bob's your mother's sister's brother. The alternative to sliprings is battery power, either with manual control or radio DMX. I'm working on a low-cost radio DMX solution and have a working prototype if you're interested. Link to comment Share on other sites More sharing options...
Jivemaster Posted April 13, 2005 Share Posted April 13, 2005 Carefull use of leds will allow rotating batteries to be used and replaced or rechargeed daily. Slip rings can be purchased there are always some at PLASA show. Low or Mains sliprings can be found from disco kit - helicoptor alligator derby effects. they can also be found in some mains motors and some car bits. All really depends on your ability to make a safe and considered and competant assembly that will do the job in budget. For a really TINY consumption even a jack plug in a socket or a low volt power connector may provide a short term solution. Or us a NATO pilot's helmet connector four poles and about 10mm DIA. A fibre optic would allow you to -using a tubular axle - spin the harness ferrule on axis in front of the fixed lamp. Message me for an old alligator, -- based London E6 Link to comment Share on other sites More sharing options...
henny Posted April 13, 2005 Share Posted April 13, 2005 a cheep and simple way for 12v is to use a 1/2" jack , down the middle of your axel , ian Link to comment Share on other sites More sharing options...
Jivemaster Posted April 13, 2005 Share Posted April 13, 2005 Given the time and need you could fabricate a set of sliprings out of a sheet of etched PCB (maplin etc) and use brass or carbon brushes on spring tails coming out of some choc block tag strip. Make the circles concentric and Q shaped and solder to the tab out of the brush track. Ideal method for multi connector system. Loads of carefull design to do to make it safe. and reliable and in budget. Link to comment Share on other sites More sharing options...
Tomo Posted April 13, 2005 Share Posted April 13, 2005 a cheep and simple way for 12v is to use a 1/2" jack , down the middle of your axel , <{POST_SNAPBACK}>Not a good idea.I've used such jacks for stationary 6, 12 and 24v power lines (needed an easily removable power plug for safety purposes in a particularly dangerous machine), and it was VERY unreliable. Every time contact was made/broken I got significant sparking and after about 10 times there were serious burns on the contacts. I expect it would have failed shortly thereafter.Didn't matter in my application as it had fulfilled its purpose by then (Technogames climbing machine), but for continuous moving contact you'd have a continuous spark and it would weld and break very quickly. Link to comment Share on other sites More sharing options...
Pete Alcock Posted April 13, 2005 Share Posted April 13, 2005 You can make slip rings (strictly for low voltage use mind) from ball races. If you get the ball races from skateboard wheels which are about 25mm outside diameter, they can be glued on to a plastic tube with the wires fed up the inside (a BIC Biro is ideal for this). This forms the moving part. Then clamp connections to the outside of the ball races using jubilee clips. Very low cost and smooth running. Get the idea? I'll see if I can post a picture of it. Pete. Link to comment Share on other sites More sharing options...
SparkySteve Posted April 14, 2005 Author Share Posted April 14, 2005 thanks for all your help guys, I thought there must have been some sort of brush moving along a ring of some sort... I think for easyness we're going to go with the battery powered option with wireless DMX. I think the only issue with using slip rings is the amount of power we were thinking about using, I don't feel it would be cost effective to use them. I could be wrong though! thanks guys Steve Link to comment Share on other sites More sharing options...
Brian Posted April 14, 2005 Share Posted April 14, 2005 Cavotec have exhibited at somewhere like ABTT or PLASA, showing slip ring assemblies. Link to comment Share on other sites More sharing options...
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