Hi,

I have built a rotating slip ring that feeds 24V from a power supply to a rotating cluster of led's hanging off a mirror ball motor. The rotating disc has two tracks made of circular copper strips. The voltage is applied to these rotating strips via multi-stranded copper flexible wires that are held against the copper strips under sprung tension. It works fine, but I am wondering if there will be chemical activity between the two copper elements of the device that will degrade performance over time? Some kind of electrolysis? I know there will be gradual mechanical wearing of the two parts.

What do you folk think?

All the best,

Leigh

 

Copper will oxidize but I'd hope the wiping action of the slip ring should keep it clean there..
Tin or silver plating the copper should help.

 

electrolysis requires dissimilar metals, copper to copper will not. you can get friction rubbing the copper down thinner, and corrosion. there are greasses that will lube the copper and protect it from oxydation.

 

This is essentially a brushed motor format. You could buy some carbon brushes and springs to keep the carbon "brushes" pressed against the copper ring. Easiest would be to buy a brush replacement kit for a Dremel tool. Carbon will not corrode and will not cause corrosion. Really depends on how long you want this to last, how smooth your copper ring is (and how many spark and associated spark-endured erosion you get). The lower the voltage (fewer LEDs you have in series) will cause less spark-enduced erosion. Same is true for a smooth copper ring (less make/break contact leads to less sparks).

 

You could also have looked at designing/modifying the pickup and rotor from a Automotive Alternator from a auto wrecker, this has two slip rings and brushes and normally carries around 2amps average.
Bearings and all would be in place.
Max.

 

Thanks for everyone's thoughts on the subject. I really appreciate them. One challenge was to construct the slip ring around the constraints of the mirror ball motor. My 3d printer was very useful to achieve that. It meant that I couldn't use "off the shelf" components. I think carbon brushes and springs would be better, but the copper ring is probably not smooth enough, and abrasion would be excessive. The current solution works well, with no sparking, I just have to see how long it runs before wear and tear and air-born dust becomes a problem.

Again, thanks!

Leigh

 

A conductive silicone or lithium lubricant will give you reduced friction and oxidation protection while maintaining conductivity. In the 60's I used TunerLube on the old mechanical TV tuners. Stay away from lubricants based on molybdenum, like MolyCoat. The grease travels on its own and can get into the wrong places.

http://www.intertexelectronics.com/GC-Electronics-10-2610-Tunerlube-Tube-1-34-Oz-P9126.aspx

ak

 

check this out: http://www.adafruit.com/products/1196?gclid=CI7hy6y3tMQCFYNAaQoddLkAMw
12 conductor slip ring, 240V, 2A, 300RPM, for $20. Unbelievable! I doubt you could even beat that with a junk yard alternator or broken dremel. I bet you've probably got than $20 tied up in your DIY slipring already; if not in materials, then in man hours.

 

And this is even smaller
http://www.adafruit.com/products/1195

 

One problem I can see with the Adafruit products is that the slipring isn't hollow. If it's going to be a motorized device, the rings could be above the motor, but that means that the wires must pass through the motor, or the motor has to be off to the side with a pulley or other mechanical drive using a hollow shaft. If it's a mirror ball setup, then I assume that the ball hangs below the motor, so those Adafruit things don't look usable.

 

That's right John. Sadly those beautiful little slip rings don't suit my application. But they certainly are great for other situations. Thanks to those who suggested them

 

Thanks for the lube suggestion. That could help. I'll trial it.

 

This company have miniature capsule slip ring and small size through bore slip ring maybe suitable for you.
See: http://www.arslipring.com