Led panel PWM control

Other Hardware General Electronics
1

Hi,
I want to control the state/brightness of my ceiling led panel through an app with the help of ESP8266. I found a few similar topics on this forum, but none have the answer I need. The driver for the led panel I'm using doesn't have built in pwm control, so my question is: "Can I use an external Mosfet PWM module for controlling the panel like in the attached diagram?". As far as I understand, the only components in that led panel are the actual leds, so it seems to me like it should be plausible, but I've gotta ask just in case. Better safe than sorry.

The images in that diagram are stock photos, but I plan on using identical components (not sure about the driver wattage though).

diagram.png
diagram.png2499×1356 287 KB

diagram.png
diagram.png2499×1356 287 KB

2

We need to see the specs & datasheets for everything you're using.

I've seen a trick with a non-dimmable constant current power supply where a MOSFET driver is connected in parallel with the LEDs and then shorted-out so when the MOSFET turns-on the current is "diverted" through the MOSFET, turning off or "dimming" the LED. But that's one of those things that doesn't work in every application.

3

If the FET module you are using is this one, then it uses an IRF520 and cannot be controlled by an ESP8266 which uses a 3.3 V supply.

4

I would certainly NOT use that particular mosfet module anywhere near a mains connection and only for limited current usage.

What is the output from the LED's main transformer in V & A ?
That would be crucial in selecting a mosfet to match the application.

5

ballscrewbob:
I would certainly NOT use that particular mosfet module anywhere near a mains connection and only for limited current usage.

What is the output from the LED's main transformer in V & A ?
That would be crucial in selecting a mosfet to match the application.

I'm planing to install one for every panel in my home (4), and their drivers differ. I don't want to bother anyone here with finding the exact parts for me. I was just curious if led panels can be controlled by pwm like that without any drawbacks.
Paul__B pointed out above that the 3.3v of ESP8266 won't do, so I would need a voltage amplifier. If I sorted that out, and found an applicable mosfet board (if IRF520 is not up to the task), would light dimming work without any drawbacks?

6

It may be that with differing power packs you may have different requirements per location.

I doubt there will be a "one size fits all" unless the differences are quite minor.

Certainly don't see any major issues if care is taken in the selection of the mosfets and its associated components.

7

I have 8 ceiling lights controlled by PWM in the manner you describe. This is one of those things where you give it a try and maybe it works just fine or maybe it doesn't. There are good reasons to expect problems, but I know it can work. If you search through my posts you should find something about what I did, including a schematic. You must use a logic level MOSFET, not using one was a silly mistake by me, I should know better.

You can't take power off the LED supply though, it's constant current.

8

I would certainly NOT use that particular mosfet module anywhere near a mains connection and only for limited current usage.

Based on the OP's Fritzing, it looks like the output of the led module is DC (black and red), so I don't see what the
issue is with PWMing, that, with an appropriate mosfet that can be driven with 3.3V. It's possible to use a mosfet
driver, a 3.3V to 5V level converter and drive the level converter with 3.3V and have the 5V output drive the mosfet
driver (running on 12V or some higher voltage) to get the OP's mosfet to work.

9

Said module is actually dodgy at 5 V - useful only for less than one Amp. :roll_eyes:

See this concurrent thread.