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This is the data sheet for your #3528 RGB LEDs. When buying a LED strip the series resistors for each LED are normally on the strip. A RGB LED has 3 each LEDs in a single package and each LED has it's own current, again the current limiting resistors should be built into the strip. The Maximum Continous Pulse Current is 25 mA for each color in each LED. Maximum Pulse Current is 100 mA (see the linked data sheet). If you figure 20 mA continuous, then each single LED will require 60 mA when driving Red, Green and Blue.
Using a 555 for your PWM (Pulse Width Modulation) will require an external driver transistor if you have more than a few LEDs. The 555 timer in this case is, in my opinion, a poor choice. You will need 3 each 555 timers, one for Red, one for Green and one for Blue on each LED. Then 3 each potentiometers, one for each color. As you drive each LED within the package (R, G & B) they will combine to make other colors. For example driving all three to Maximum will yield White.
A better choice is to use a uC (micro-controller) letting three potentiometers drive three analog inputs and using three PWM outputs to drive three MOSFETs which can handle an entire string of LEDs.
Ron
Using a 555 for your PWM (Pulse Width Modulation) will require an external driver transistor if you have more than a few LEDs. The 555 timer in this case is, in my opinion, a poor choice. You will need 3 each 555 timers, one for Red, one for Green and one for Blue on each LED. Then 3 each potentiometers, one for each color. As you drive each LED within the package (R, G & B) they will combine to make other colors. For example driving all three to Maximum will yield White.
A better choice is to use a uC (micro-controller) letting three potentiometers drive three analog inputs and using three PWM outputs to drive three MOSFETs which can handle an entire string of LEDs.
Ron
