Electronics > Projects, Designs, and Technical Stuff
film grade controller for rgbww leds
tooki:
Depending on how much granularity one needs in terms of brightness, one flickerproof, color-shift-free approach is simply to control how many LEDs you turn on. For example, with an array of 512 (single color) LEDs, you have 512 levels of brightness control by simply turning individual LEDs on and off. With a really good diffuser, this would produce great control. Similarly, by controlling the ratio of RGB and WW/CW LEDs are on, one can control the color and color temperature, respectively.
vns:
Maybe a teensy 4.0/4.1 is all I need? 12bit at 36khz out of the box, and I can easily add dithering. https://www.pjrc.com/teensy/td_pulse.html
vns:
I am back :)
I ordered a Teensy 4.0 for testing, this is what I get in a 1/4000 shot @ 36621.09Hz which is the max frequency for 12bit resolution.
A huge different vs the picture I posted using the Yeelight bulb but not perfect yet, so yeah, not an easy to fix problem.
For video purposes, at least with my camera, it seems that 5khz is enough to remove the banding completely when shooting @ 24p(1/50 shutter speed), so 36621.09Hz is probably safe for any video shooting.
Anyway, now I need a way to drive my leds, I order a 4m stripe of rgbww leds, I don't know how many leds I am going to use but it is going to be less than the whole stripe (which contains 240leds). The 4m take aprox 1.1A per channel. I want to keep everything as simple as possible, so I am thinking about some logic level mosfet maybe? I want to controller the gate using the PWM pins directly, 3.3v in the teensy, so I need a mosfet or other type of transistor that is fully open @ 3.3v, but it also should be able to handle the 36khz PWM frequency.
When it comes to spec sheets I am a little bit lost, is the IRF3708 the right choice? I just want to avoid a driver circuit for the mosfet itself. I truly need some help. here.
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