Friday, March 16, 2012

First 555 Timer Project

As the title says, this is my first time using 555 timers :). I have three timers on the breadboard, each is hooked up to a color of a RGB LED.They all have a about 50% duty cycle, but are set for different pulse lengths so that it blends the colors randomly-ish. The 555 requires two resistors and a capacitor to set the duty cycle and pulse length. I could, but id rather not, do the calculations for finding which cap/resistors to use, so i found this program which does it automatically.

The following is the basic 555 scheme i used to build off of. R1, R2 and C1 change the pulse and duty cycle. R3 is the current limiting for the LED. Also; the 555 can source or sink a max of 200ma.

The resistor and cap calculator
Don't mind those NPNs/PNPs in the center;
 they're from a different project 


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