Planned Project with Potentiometer, LEDS, and PWM

Using Arduino Project Guidance
#1

Hi. I've done a little with arduino in the past, but it's mostly been using pre made code (grbl, etc), so starting from scratch is new to me.

I've watched quite a few videos and read some forum threads and I think I've got my head wrapped around the basics of what I'm trying to accomplish. Before I start trying to physically do it though, I would love to double check my idea and make sure it's actually possible to do before I start pulling my hair out trying to piece together the pieces of code I'll need.

What I would like to do on a most basic level is use a potentiometer through an arduino to dim an LED with PWM. I'm planning to use higher power cob LEDS, so I believe I'll have to run the signal through an N channel mosfet to be able to handle the higher power requirements of the LEDs. First issue/question is this light is going to be used for video, so I need to avoid any potential PWM flicker. I think that means, I need my PWM frequency to be at least 10k. I read a discussion and they mentioned using Timer1 library to get a PWM frequency that high. I also know there is a PWM library, but the one video mentioned the upper limit of that library and I don't think it was going to be high enough to get to 10k. So far is this all make sense, possible?

The next level in the final version I would like to expand this out to 5 different channels if you will, each with a pot and mosfet to drive multiple sets of LEDS independently. I believe the nano and uno both have the same number of PWM pins, 6?, and I think the nano actually has more analog pins, so is there any reason I couldn't get all of this to run with a nano? And if I can get this working with 1 potentiometer/mosfet/led, is there any reason I couldn't do it with 5 channels?
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#2

High power COB-style LEDs usually means a LED driver, not just a mosfet.
LED drivers use high frequency (about 500kHz) to keep LED current constant.

For video I think you shouldn't PWM the driver at all (no flicker),
but smooth the PWM from the Arduino into DC before presenting it to the LED driver.

Which LED driver will depend on the COB LEDs you're going to use.

Yes, the Nano has six native PWM channels, and enough analogue pins for pots.
Leo..

#3

Wawa:
High power COB-style LEDs usually means a LED driver, not just a mosfet.
LED drivers use high frequency (about 500kHz) to keep LED current constant.

I should have been more specific about the leds. Initially not looking for anything too extreme. More something like a 12v/10w cob or a pair of them.

Wawa:
For video I think you shouldn't PWM the driver at all (no flicker),
but smooth the PWM from the Arduino into DC before presenting it to the LED driver.

Could you elaborate on smoothing the PWM from the arduino...?

Thanks for the feedback so far. Glad it seems like at least the i/o wouldn't be an issue.

#4

An easy way to start with 10watt COBs (the 3*3 ~10volt variety) is to use an old 19volt laptop supply and a ~900mA LED driver.

Most LED drivers can be brightness controlled by

  1. a Voltage (0-2.5volt or 0-5volt or 0-10volt)
  2. a potentiometer
  3. PWM

If you just want brightness control with a pot, then you might not even need an Arduino.

Can make a DC voltage from PWM with a resistor and capacitor (RC low-pass filter).
Leo..

#5