12V DC Motor in Light Fixture with Dimmer & 12V DC to 110V AC Inverter - Page 1
Forum section: electronics / projects

author: CB33
author_rank: Newbie
timestamp: August 21, 2024, 09:19:59 pm
content: I have a question regarding a light fixture I'm building that also has a motor in it. It has geometric shapes that spin slowly around the light (almost like a mobile) and this is what I'm using the motor for. The light fixture will be attached to the ceiling like any normal light fixture or chandelier and I want to use a light switch on the wall to be able to turn it on and off. The light bulbs will be powered by 110V AC. The 12V Synchronous DC motor will be powered by 12V DC. I am using an Inverter which is 12 Volt DC To 110 Volt AC which will be able to accommodate turning both the motor and bulbs on with a flick of the light switch on the wall.The question I have is in regards to a dimmer switch. I want to use a dimmer switch to be able to make the lights brighter or dimmer. However, because the motor is also being controlled by the dimmer switch I want to know if this will be a problem and what will happen. Will it slow down the rotation? Will It damage the motor? If it will pose a problem are there any simple solutions or work arounds? I haven't purchased the dimmer switch yet. Is there a certain type that will work with this or a certain type that won't?Just to clarify why I'm going about it this way. Initially I was just going to use an AC 110 V motor so it would all be on AC. The problem was getting UL approval because of the motor. Because I'm using a 12 V DC motor instead it is kind of a loophole for me so I can get UL approval without all the headaches. Using a 12V DC motor will not be a safety concern in terms of UL certification.The motor I'm using is a 12V Synchronous DC geared 1 RPM motor. It's just a simple one you can buy on Amazon and I'll post the link to it:https://www.amazon.ca/gp/product/B07YFJR62T/ref=pp...Also, on a side note I'm not sure what inverter I should use for this project. The choice is between a constant current inverter/driver vs constant voltage inverter/driver. I'm not sure which one to use here.Any insights would be greatly appreciated. Thanks!

author: Kim Christensen
author_rank: Super Contributor
timestamp: August 22, 2024, 01:16:59 am
content: I think you've got your terminology all mixed up. Kind of like the Amazon link to the "12V Synchronous DC geared 1 RPM motor"... (It's NOT synchronous, but I doubt you'd need that anyway)Are you questioning whether the power supply included with the motor will work on a dimmer? The answer to that would be no. It'll probably work when the dimmer is turned up full, but then shut off or completely fail with a bang when "dimmed".

author: amyk
author_rank: Super Contributor
timestamp: August 22, 2024, 01:44:22 am
content: This sort of application almost always uses a capacitive dropper.

author: NiHaoMike
author_rank: Super Contributor
timestamp: August 22, 2024, 02:03:59 am
content: Have you considered a microwave oven turntable motor? A lot of them run directly from 120V. Most likely the only additional things you would need to do for UL would be to fit an inline fuse and ground the motor casing.

author: CB33
author_rank: Newbie
timestamp: August 22, 2024, 11:32:23 pm
content: Thanks for your reply. If it's not too much trouble can you please explain how a capacitive dropper will help in this instance? What do you think if I were to add a rectification stage input to the power converter to store the input energy on a capacitor for the 12Vdc output converter? One of the things with this light I need to get parts that are already UL approved and if I were to do this do you think this would pose a problem getting this UL certified?

author: CB33
author_rank: Newbie
timestamp: August 22, 2024, 11:34:50 pm
content: I also just added a diagram so hopefully this explains a bit more about what I'm trying to do.

author: Kim Christensen
author_rank: Super Contributor
timestamp: August 23, 2024, 12:03:54 am
content: Your problem is going to be running the 110VAC --> 12V power converter via the dimmer switch. That's not going to work very well.One solution is to replace dimmer switch with an ordinary switch. Then install one of those "smart" bulbs and use it's AP to dim/control it. The only trick would be finding a smart bulb that's not finicky. (Needing resetting or reprogramming on power loss)