I know there are many questions floating about "howwant to drive a LED" going around (and many many good answers), but please bear with me.
The concern is how to make sure that my LED's don't have any sort of flickering, not even "micro-flickering" that's undetected by the human eye, as that can have health effects on both humans and plants (here are a couple of anlisys: https://www.digikey.com/en/articles/techzone/2012/jul/characterizing-and-minimizing-led-flicker-in-lighting-applications, https://www.azom.com/article.aspx?ArticleID=12161).
As I understand, LED micro-flicker may come from 3 sources:
- Noise carried over from the AC line
- Noise carried over from up-regulation of the AC frequency (present even in most high-frequency switching power supplies)
- Flicker introduced by PWM for dimming
Here is my current prototype which should eat up about 72W if my math is right. I'm calculating the "ideal" Vf for each LED based on meassurements for the min and max Vf and max If, procuring the voltage never causes the current to exceed 76% of the max If. All the data of the components in link is according to reality.
I'm using the 12v rail of a PC PSU, because I thought "hey, this thing's used for powering micro-processors, it's gotta get rid of 1 and 2, right?" (though I haven't assertained that with an oscilloscope yet).
I'm guessing eventually I'll use a commercial 12v switching power (unless I realize that they all have problem number 2).
As for why I care about problem number 3, well, I'd very much like the lamps to be dimmable, quite possible controlling the diming from a micro-controller which (I hope) would be able to take the LEDs from fully-off (ie, just below the Vf) to fully-on (zero resistance, besides what I've put before each series).
Are there better ways to get a stable noise-free powerline? or to regulate the current programmatically without using a PWM?
Q: What is an efficient and cost-effective way to drive and regulate brightness for high-power LEDs ensuring a light output that's free of micro-flicker and as free of noise as possible?