Dimmer for LED bulbs

[GZGZ]

Hi everyone,

I have some 230V dimmable LED bulbs (80 W in total). Reading online I saw that usually this type of bulbs work better with trailing edge type dimmers (compared to leading edge type dimmer). I took a look online to see if there is a trailing edge dimmer module that I could simply control with an Arduino for example giving a 0-5V input (something like **broken link removed** for example), but I couldn't find any. I was wondering if someone knows about such a module.
I would also consider to build one myself if no pre-built modules are available, but my knowledge in electronic is quite limited, so the first solution would be preferred.

Thank you

 

[andre_luis]

The LED lamps, even the dimmable ones, in general do not work very well at low triggering angles. This occurs because these lamps has a very low power consumption, therefore even with the smallest smoothing capacitor it will be not able to sustain an average bright within each cycle of the mains, showing a perceptible scintillation. If you plan to do a nice product, I would recommend you consider rectifying the wave and then making a PWM-based control.

 

[GZGZ]

Thank you andre_teprom for your reply.
Is it not a problem if I apply a PWM signal to a lamp that contains already electronics inside?

 

[andre_luis]

I was not exactly referring to directly apply PWM pulsed voltage there, but filtered by a capacitor.

 

[GZGZ]

Sorry but I am more confused now.
Filtering a PWM you will obtain a variable voltage source, but since the LED are current controlled, what is the benefit of doing so?
Could you explain it to me a bit more?

 

[andre_luis]

I'm talking about how to generate output, you're talking about how to measure the output.
One is somehow affected by other, and considering a feedback control, don't matter, isn't it ?

 

[GZGZ]

You are being too cryptic for me. Can you expand what you mean?

 

[andre_luis]

You're right, it was not even a little clear. Anyway, I was just considering that, as you said, once your knowledge in electronic is limited, an approach based on phase control could be more complicated to achieve, and a current control based on varying duty cycle of the PWM in theory is expected to be somewhat linear. Regarding your concern to have an electronic driving the other, I do not consider it in principle being a problem.

 

[GZGZ]

Thank you for the explanation.
In the case of current control, how would you select the maximum current to apply to the LED bulbs?
I took a look online but I wasn't able to find much about this kind of applications. Could you please point me somewhere where I can read about current control PWM in more detail?

 

[andre_luis]

Have you datasheet/specifications of the product ?

 

[GZGZ]

I don't have any datasheet of the product, but while I was looking for it online, I found the same product on amazon (**broken link removed**) where it specifically says that this type of bulb is compatible with trailing edge type dimmers. Should I stick with this type of dimmers then? And if so, any similar circuit where I could start?

 

[andre_luis]

Should I stick with this type of dimmers then? And if so, any similar circuit where I could start?

First of all, considering that you don't want to take a fatal electric shock, should use optocoupler to isolate the Arduino side from power side. I'm assuming that you have not enough experience with mains voltage handling.

The simplest way you can do with no chance of bother is by PWM as mentioned above. There is no plausible reason to this lamp do not work controlled by a DC voltage took from a rectified circuit ( bridge diode + electrolitic capacitor ). The dimming action would be made by a buck converter (step-down converter). You can find a lot of information available on the Web about how to implement the timming control logic for this.