Hello, I've been trying to make small installation to work properly. I've connected 16 fans 12v 2 pins. I'm trying to control them with PCA9685 and Arduino setup. I've connected everything and i works well when i'm trying to send one code to all of them like this: #include <Wire.h> #include <Adafr…

The last sketch in post #28 will prove if the OP can adjust the speed of their fan. Using PWM and a MOSFET on a 2 wire brushless fan can damage the internal circuit capacitors, the OP said longevity is not an issue. Need to settle on the PWM frequency and the effective duty cycle range that …

I have tried both codes but unfortunately the fan is not responding to either of them. I cannot see any movement or indication that the fan are getting signal. I double check after powering it up again if they react to this code (to make sure that everything is connected and responds to arduino): #…

That sounds like we are worse off today :frowning: Place a LED from the output 0 pin to Arduino GND. Do you see the LED light up ? [2026-02-08_17-47-43] #include <Wire.h> #include <Adafruit_PWMServoDriver.h> Adafruit_PWMServoDriver pca1(0x40); //======================================= v…

It doesn't work sadly with your code. [2] But when i just turn it on to check if connection works, it did work: #include <Wire.h> #include <Adafruit_PWMServoDriver.h> Adafruit_PWMServoDriver pca1(0x40); //======================================= void setup() { Serial.begin(115200); Wire.beg…

[2026-02-08_19-35-25] [2026-02-08_19-23-12] Also, check that it is not installed backwards !

Yes, this is the connection to the second PCA9685. These not connected pins are V+ and VCC. I am powering VCC directly from a 5 V power supply, not from the Arduino. Each PCA9685 is supplied separately, so there is an additional power cable from the 5 V power supply to the second PCA as well. GND is…

You are a genius Larry. It was inverted, was supossed to omit VCC and V+ not GND na OE. Now everything works. Fans work too. My God, i wasted 8 days trying to figure it out. Thank you!

:clap::+1:t3::zany_face:. Perfect

Glad you have it working. :+1: Still don't fully understand how you have things wired. It is necessary the Arduino, and two PCA9685s be powered from the same source. Highly recommended you wire the 3 PCBs as per the schematic below ! [2026-02-10_00-17-20] EDIT Made minor changes to th…

I see, I believe that makes things much easier. I will change it then. I was also planning to use those motors: 3V~6V 130 DC Toy Motor DIY I was using a 5V power supply because I was planning to eventually connect these motors to PWM as well, I've read that if there are many PCA connected in the …

Arduino, Pca9685 and 16 fans 12v - art installation

Projects General Guidance

LarryD February 15, 2026, 7:59pm 48

Mount your PCBs properly using M2 hardware.

Look into using Brass Inserts if applicable.

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Arduino, Pca9685 and 16 fans 12v - art installation

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