How make a rgb led mixer? Parameters:(with 3 led, 3 potentiometers, 3 V) (without PIC) I would like a schematic diagram?

5. Generating a Variable Voltage with a Potentiometer

In this last step, you'll generate a changing voltage using a potentiometer. A potentiometer is a resistor that can change its resistance. A potentiometer (or pot) has three connections. The outer leads are the ends of a fixed value resistor. The center lead connects to a wiper which slides along the fixed resistor. The resistance between the center lead and either of the outside leads changes as the pot's knob is moved.

Solder hook-up wires to the pot leads as shown here. Then connect the pot to an LED and a 220-ohm resistor using the following circuit:

As you turn the potentiometer from one end to the other, measure the voltage at the center position. The pot is acting as a voltage divider, dividing the 5V into two parts. As the voltage feeding the LED goes up or down, the LED gets brighter or dimmer. The 220-ohm resistor in the circuit protects the LED from overvoltage when the resistance between the pot's 5V lead and its center lead is 0 ohms.

You'll learn more about voltage dividers and potentiometers in the analog input lab.
All the information you need is in my answer :- Look at the specification of the LEDs you're using. The red one will be something like Vf = 1.8V, If = 20mA. Put these numbers into the calculator I've linked along with your supply voltage and it will come up with the value for the resistor (for example 180R if you're using a 5V supply). The circuit for each LED will be exactly the same as the calculator shows you, except you'll also put in a potentiometer in the circuit as well, like THIS. What voltage are you going to be running it from?
Well, You could simply just connect each LED in series with a potentiometer but you could still pass too much current through the LED when the potentimeter is turned all the way around. You need to specify what the forward voltage of the red, green and blue LED's are for me to make a schematic that's precise...