I need to control 17 dimmable LED strips each cut to length 1m (10W/m; 120LED/m; 24VDC).
Each led strip needs to be controlled separately and to be dimmable. Is there any good simple way to connect all of them on Arduino UNO?
I am quite new to this so I would need some help on how to accomplish this.
Thank you!
To control 17 dimmable led strips you need a 17 PWM outputs, but the Uno has only six.
You can you use PCA9685 16 channel PWM controller for 16 strips and control the last strip by Uno itself
Can this LEDs be then connected to external power source and controlled with this 16 channel PWM?
Yes
Yes, but not directly, but through mosfets, because the voltage and current of your led strips are too high for this module
You don't need to be limited by the Arduino's restricted number of PWM channels. To drive lights, you can use a much larger number of software-generated channels. But then you'd have to set up a shift-register chain to get the data out of the Arduino, because it hasn't got enough pins to drive 17 channels. Or maybe you could set up a 4x5 matrix somehow? But that's probably too complicated to be worth doing.
Does it really have to be 17 channels? 16 would be much simpler to deal with.
It can also be 16 channels. I can change the design a little.
Will the mosfets change the brightness of the led strip? If yes, then this wont't be ok for this project.
What arduino board do you mean, which doesn't have a 17 output pins? Arduino Uno has a 18 GPIO, even if not take in account a 0 and 1 pins
Oops, I didn't stop to think about how many pins the basic Arduino actually has. Yes, it could be done with 1 pin per channel. But it would mean there's not room for much else. Question for the originator of this thread--how is this device to be controlled, via a serial link perhaps? That needs some port pins too.
@veqlargh wants to be able to dim each LED strip separately, so if standard GPIO pins are used that would involve using software PWM to control each of them. At best this would be inconvenient
@UKHeliBob
Using regular pins as software PWM is not my suggestion, but @Beminetonight
I was just reacting to the statement that the Arduino Uno does not have enough pins to connect 17 outputs 
Why?
Is a changing the brightness not what you want? Is it not the same as "dimming"?
You will not notice the difference. Just like you will not notice the difference between PWM 254 and PWM 255 when using an Arduino's 8-bit PWM output.
I ment the top brigtness.
What about if I use 16 channel multiplexer and I connect to each channel mosfet controller. Would this work ok?
In that case you will loose brightness. Each strip will get a signal (be switched on) for 1/16 of the time.
Be careful with the MOSFET modules; they need to use so-called logic level MOSFETs.
Can you post a link to the specific LED strip you are using?
The assumption is being made that these are single-color, non-addressable LED strips.
In this case you will lost the top brightness way much than with 16ch PWM module + mosfet scheme
I have not yet bought any LEDs. So If I read correctly I could use addressable LED strip to achieve this without additional mosfet or pwm.
Yes - exactly.
