Slow disco/mirror ball rotator - Page 1
Forum section: electronics / projects

author: none
author_rank: Contributor
timestamp: November 23, 2024, 08:50:26 am
content: Sorry, not sure this subforum is a better fit than the others..My cheapish 1,5 rpm mirror ball motor is too fast, I want it to turn slower.It appears to be a geared AC motor (see e.g. bigclivedotcom's video on YouTube).Dimming doesn't work well with synchronous motors.Changing gears is probably too involved.Using a variable frequency drive is too expensive (though there appear to be cheap VFDs for around 50USD) and may not work well or safely with this kind of motor and low frequency.Are there cheaper BLDC options for a very slow direct drive (Odrive etc.)? Essentially that's also a VFD with separate supply.Probably the simplest would be a stepper or geared DC motor?Probably stepper and belt drive would be less noisy.In addition, the bearing needs to be Fail-Safe so the whole thing can't fall down on anyone. Not sure what the actual requirements are and how the commercial ones implement that, but they are usually rated for mass and have a secondary safety hook.I'm thinking that if something breaks, it shouldn't be possible to just drop out of the contraption. So maybe something like a T-shaped shaft (bolt with washer) that can't fall out of the housing even if the bearing etc. disintegrates). And if that should fail, the backup comes into play.Does that make sense? Just here to bounce off these ideas and get some feedback 😁

author: Andy Chee
author_rank: Super Contributor
timestamp: November 23, 2024, 09:04:20 am
content: Continuous rotation DC servo motorHow heavy is the mirror ball? How big is your existing motor?

author: none
author_rank: Contributor
timestamp: November 23, 2024, 11:50:05 am
content: The motor is rated for 4 kg, not sure how much power it takes. Can't be more than a few watts.Servo motor is a good idea, but ideally, the drive is silent.

author: themadhippy
author_rank: Super Contributor
timestamp: November 23, 2024, 12:48:47 pm
content: signal generator and a power amp,for bonus points make the signal generator frequency controlled by dmx

author: inse
author_rank: Super Contributor
timestamp: November 23, 2024, 01:18:07 pm
content: Plus a transformer to step it up to mains voltage - that’s overkill, too.Swapping the motor for one with a different gear ratio is not an option?

author: none
author_rank: Contributor
timestamp: November 23, 2024, 08:28:58 pm
content: I'll look into the AC generator with transformer, it could be less complex and a little safer than a DIY VFD.Off the shelf "rotators" all seem to be in that rpm range. Don't know if the actual motor is available with higher gear ratio. I'll have a look around.Thanks for the ideas!

author: Someone
author_rank: Super Contributor
timestamp: November 23, 2024, 09:39:43 pm
content: You buy it rather than trying to solve all the engineering issues:https://www.avecorp.com.au/product/lmm-100-dmx-mirror-ball-motor-large-10kg-load/Plenty of options, ask your local distributors for suggestions.

author: themadhippy
author_rank: Super Contributor
timestamp: November 23, 2024, 09:52:17 pm
content: Quoteindeed you can,prices start at around £100