Hi!
I have a project where I want an arduino to detect the position to a 220v dimmer to make it adjust the position to a stepper motor. So when I turn the dimmer a stepper motor will adjust accordingly. It’s for a mechanical dimming lamp design. How would I be able to accomplish this?
Thank you in advance!
An absolute shaft angle encoder could be attached to the dimmer shaft.
Thank you for answering.
I’m looking for a way to connect it to any dimmer without modifying it. I would like a circuit that can read the state of the dimmer
Use a camera to photograph the dial setting, followed by image processing on a PC.
If this sounds unreasonable, it is because your requirement is unreasonable and/or unrealistic.
Turn the design around and make the stepper motor turn the dimmer control.
So it’s no way for an arduino to detect the position of a dimmer by detecting the sinu waves?
For help on this forum, you need to clearly describe what are you actually trying to do, that is, the real problem.
You could start by explaining what the dimmer does, and describe the nature of the "mechanical dimming lamp design".
What is the stepper supposed to do, and why does its shaft position matter?
Sorry new here. I’ll try to explain better
I want to make a lamp that dim mechanically instead of like they normal do by reducing the amount of light from the LED bulb.
A dimmer works by cutting the voltage at different points in the AC cycle, reducing the power sent to the light.
So what I want to do is making a motor of some sort adjust som blinds or the shape of the lamp to allow more or less light to pass. And I want this to be done with the dimmer switch allredy installed in normal 220v electricity circuits.
So I basically want a way to make the arduino detect the state of the light dimmer
Hope this makes it easier to understand
so you could read the AC wave with a CT or Hall effect sensor and analyze how much of it is cut.
but maybe it is simpler to use a Triac module with a zero crossing detector to dim AC than control a nob with a motor and read the result from an AC wire.
I think @Juraj has the right idea with the Current Transformer (CT).
Maybe, but I think it's crucial to @hiimjo's concept that existing dimmers, possibly integrated into wall fixtures, can be used. So he needs a way to 'read' those dimmers and then act upon that value.
@hiimjo a problem I notice with your concept is that if the original dimmer is present, your system (including the light and the motor) will have to function at a reasonable range of dimmer settings. This may or may not be feasible depending on your choice of components and the total power draw of your electronics. Think also of the situation where the dimmer is at a low setting, but it's being dialed higher, so that you'll have to run the motor to move the blinds/beam shaping fixture/etc.
But this relies on power consumed. I think the whole point is that this is not necessarily tracking with the actual setting of the dimmer as such. The challenge this would bring is that you can't simply rely on the magnitude of the current reading as such; you'll actually have to figure out the cutoff point of the waveform to determine the dimmer setting. It can be done of course.
@hiimjo is this intended to become a commercial product that needs to work with whatever dimmers people happen to have in/around their house? If not, I'd seriously consider a much simpler approach and depart from the requirement of using existing AC dimmers.
Thank you for this detailed answer. I’m product designer student and yes this would be for a prototype that potentially could be a product for mass production. So the idea is that this is a lamp that a person would buy and then connect to their existing dimmer.
Off course a final product would have more advanced electronics than an arduino, where you f.eks would be able to calibrate the lamp to your dimmer and possibly control it even more with different on of patterns or 100-0% two times maybe?
My goal now is to try a make a prototype that actually works with a dimmer, and I thought an arduino might be the answer, but maybe I need something else?
Ok, see if you can find someone working in the field of electronics engineering to collaborate with. You're working with live AC and there are evidently risks involved in this.
Also google how dimmers work, and in particular look into the concept of phase control or phase cut. This is how most AC dimmers work.
Having said that, I'd start by taking a regular transformer (not an SMPS!), let's say 220V to 9V or so, and connect it to a dimmer. Monitor the secondary/low voltage side with a scope. Observe what effect different dimming levels have on the waveform. This is the pattern that your device will need to recognize. I expect that it'll be sufficient to record the period between the moment of zero crossing and the next non-zero voltage. This will be longer for lower dimmer settings and it'll be virtually zero for 100% level. 50Hz or 60Hz is pretty slow so even a basic Arduino Nano has plenty of computing power/speed to keep up with this task.
As I said, one of the challenges is for your device to operate reliably also if the dimmer is set to a very low level, and it'll have to behave nicely between this minimum threshold and full off. You don't want flickering disco lights, let alone fireworks in this scenario. This will require some attention in power supply design and again, it depends on what kind of load you will want to feed. I assume you'll be working with fairly low power LED lighting, which makes things easier.
One point of critique you'll bound to run into (here it is) is that you're designing a product that effectively wastes power while dimming. In the greater scheme of things, I don't expect the planet is going to fall apart because of your invention. But in this day and age, I would challenge you to come up with an equally creative concept that is also energy efficient. Why create e.g. 20W of led power if all you need is 2W of light output? Surely, the elegance of efficiency is bound to be a design concept in your field, in some way. I hope.
Thank you for a very thorough answer!
Your point is valid and it is something I definitely have to think about in my study. So most likely it would be more of an achievement for my self technically and maybe not for a potentially product
But thanks a lot for your help and input !
you skipped "and analyze how much of it is cut."?
So are you still interested in the CT approach?
Using a CT is quite safe.
You can use a cheap Uno or Nano
Point taken; I do believe though that the low and potentially variable load of the circuit itself will be a complication when trying to use a CT. I'd lean towards a simpler optocoupler circuit instead, or something along those lines. Not necessarily a current-based sensor system.
Remember, the dimmer circuit is ALWAYS in operation, even though no AC current is flowing in the circuit. Your dimming project only shows the dimmed light if current is flowing.
and rectifying that to get a DC voltage that is in proportion to the dimming level.
Measure and react.
I haven't read carefully and may not have seen this suggested or rejected already.
a7
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