Looking for a simple circuit ... (LEDs) or similar lighting sources? Here is an Arduino based circuit with three independent pulse width modulated (PWM) channels to fulfil your requirements! Just ...

and use the “analogWrite” command to control the duty cycle, as shown in the below experimental sketch prepared for Arduino and ATtiny85: int PWM_pin = 9; // LED pin for Arduino Uno (D9) //int PWM_pin ...