An artist friend wants to fill a window display with 10 or 20 rotating disks, maybe paper plate size, maybe some bigger. Some disks might be paper plates, some might be 1/4" plywood. Some might be horizontal, some more vertical. Low RPM is better than high – maybe 2-5 secs per rotation.
He’s imagining little battery powered electric motors. I’m thinking AC might be more practical. The display might be up a month, and might be running 8 hours a day.
Thrift store buys are okay, if the products are widely available. A maximum budget might be $400.
AC is definitely the way to go. Batteries in a window display are going to need to be replaced or recharged probably a couple of times per day, maybe a bit less if you use larger batteries.
American Science and Surplus has always been a great source for inexpensive gear motors. They sell surplus stuff, so what they have available constantly varies. You can look on their web site to see what they currently have in stock.
Amazon has some decent motors too.
A fairly tiny motor can do the paper plates, but you’ll need a bit more oomph for the plywood disks since they are going to be heavier.
The little DC motors can be run with DC transformers (wall warts). They are probably too fast for the OP’s requirements though. Even though easy to control speed with voltage they will not have any ‘oomph’ at minimum speed. Some AC gearmotors run very hot and may not be suitable for mounting in a display window for safety reasons.
I’ve seen moving window displays with batteries that last for days on a couple of C cells, though that’s usually for a back-and-forth motion like a waving cardboard cutout, not a steady rotation. The motor itself has a pendulum with a magnet on it, and contains an electromagnet that’s only energized at one moment of the magnet’s movement.
Of course, everything needs to be well-balanced, but that’s pretty easy with circles. And replacing batteries every few days might still be too much.
Depending on how technical you are, and how much work you want to do, these might work, especially if you want to be able to control speed and direction. I used these to build a watch winder out of. It would randomly turn on and change speed and direction in order to keep the self winder going.
Exactly. Just buy a bunch of these. The only thing is you might need a multi-port USB charger and multiple USB cables of the right variety (assuming the display stands don’t come with them) but at least all of that can be reused elsewhere.
Thank you everyone for input (samples quoted below). I did find some promising DC geared motors on Amazon, by including “15 rpm” in the search. (Like this one…)
USB power might be ideal, but the display turntables seem to be a bit too slow (8 to 30 seconds per rev, and the cheaper ones around 15 secs), and are pretty massives. But it’s promising and will get further exploration.
I’m only slightly electrically competent. Is there a simple safe way to power multiple 6v or 12v motors from a single AC adapter?
The Surplus Center is the place to go for this sort of thing. Man, I used to love their catalog. This should be a list of small, AC gearmotors sorted by price:
Yes. You need a transformer that can handle the combined current from all the motors. The one in your link specified .09 amps, so double that and add up the total from every motor. So if you have 5 of them you need a 1 amp DC transformer which is pretty small. Many wall warts like those used on PCs have AC output, you need DC. You can connect every motor to the 6V or 12V output and ground from the the transformer. Get someone with practical experience to help you.
The low voltage isn’t going to give anyone a shock but the motors can get hot, probably create a spark, and poor connections can produce sparks also. Very little chance of danger, but you have to understand that the outside chance of a spark igniting a fire may not be covered by insurance, especially on a commercial property. So take every precaution to make sure wires aren’t exposed, and enclosing the motors in a safe housing.
A cheap universal adapter will be just fine here. For instance:
Note that it includes a “DC terminal connector”, i.e. a screw terminal. Set the adapter to 12 V, screw some wires into the terminal connector, then use wire nuts to fan out more wires from there that go to each motor. Color code everything red/black and it’s hard to go wrong.
Sure, I’d personally solder everything nicely for a cleaner result, but it sounds like that might be beyond the skill level here. And keeping things at a safe <12 VDC is important, I think. 2.5 A will drive many small DC motors.
That looks simple and safe enough for this project. I’ve ordered it along with a 10 rpm motor. And some “flange coupling connectors” that will attach to the motor’s 6mm drive shaft.
If those function together I’ll order more motors and work out the branched wiring. Probably the motors will get mounted to the ends of 1x2 lumber with hose clamps.
