Ben’s L.E.D. Marquee – “The design is relatively straight-foreward.One of the 555’s set the rate you wish the individual LED’s to turn on ( and off). I set this at a 50% duty cycle so it looked like the “spelling” of the word looked uniform. The other 555 sets the rate at which the turn on and turn off sequence begins. I used a skewed rate to keep the name lighted longer that when it toggles to its off cycle. These two 555’s are entirely set-able depending upon the behavior you wish to have. The device utilizes a cascading concept. The 555 starts off the first 74LS164 with a HIGH signal to pin 1, which sequentially shifts high the outputs Q0 thru Q7 ( pins 3-6, 10-13) at the clock pulse. Cascading the signal is as easy as tying the final output Q7 (pin 13) in your 74LS164 to the input (pin 1) of the next 74LS164.” – Link.
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