Electronics > Projects, Designs, and Technical Stuff
Slip Ring
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daqq:

--- Quote ---Does anyone have experience with the Slip Ring components?
--- End quote ---
We use some really expensive slip rings for one of our devices and the only issues we've had was when the material started corroding when exposed to something nasty. Completely our fault, can't blame the rings for that. Basically, a laminate structure was not cured properly and started emitting something nasty.

What I've heard of from the cheaper ones are issues with higher current (sparks and such), very short disconnects. And of course life time.
beanflying:
Two minute look at the http://www.chinagoco.cn/c1098.html SRC-22-06A brought off evilbay.

It resisted my spudgers so I used a little more persuasion  >:D

Front and back are magnetic so there appears to be bearings front and rear I suspect the reason for the 250-300RPM limit is more about balance and contact bounce as the plastics are not perfect. So take the dimensions as a guide more than gospel.

The remaining bits would be great to make into a custom 3D print and much more compact than the full outside housing. Guisstimate on current 100mA and strictly sub 100VDC IMO regardless of claims.

EDIT pulled out the soldering scope and the contacts are better than I thought dish shaped washers either side of the contact wiper.

Re EDIT turns out the two halves are not glued and yes it did go back together afterwards  ;D
richard.cs:
I am dubious about serial data without error correction being passed over low-cost sliprings. I'm sure it will work most of the time, but there's a high chance that contact bounce will causes glitches in the data, or stray clock edges that misalign everything by a few bits and I suspect it will be quite visible. A fast update rate may help in that glitches then get overwritten and most errors appear as brief flashes rather than LEDs that get stuck in the wrong state until you next want to change them. Really you'll just have to try it and see.

Then best solution is probably to have two microcontrollers, one on the ferris wheel controlling the LEDs and the other outside doing the user interface. That then allows you to create a robust, noise-resistant protocol over a slipring between the two microcontrollers. Even without any protocol effort microcontrollers are likely to be more robust as they will have UARTs which do majority voting internally and ignore a lot of glitches.
Psi:
If you use a slip ring with double the number of connections you need you can parallel them up in pairs.
This will reduce any issues if one should glitch.

You can also add some capacitors on each side to smooth things out should the ring glitch.
For data connections you can still add a cap, you just have to check that it's small enough not to corrupt your data.
For slow speed signals this is easy to do e.g. (9600 baud).

beanflying:
All the chat about a glitch here due to a bounce here or there we should remember this is for a Model Ferris wheel not a Rocket headed for Mars  :)

Rotational speed is likely to be sub 5RPM so the chances of bounce are low? Twisted pairs and shielding would help as would a Low baud rate and maybe still leave room for some error correction.
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