Electronics Forums > Electronic Projects Design/Ideas

How do I draw a truth table for this!???!

(1/1)

bobleny:
My teacher said I should make a truth table for this (Not as an assignment) but I have no idea how to make a truth table for this circuit.

Could someone give me a template or tell me how I could do it?

Thanks!

--------------------------------------------
I figure one of these will work for you! They are all of the same image.

http://img206.imageshack.us/my.php?image=64leds2mm7.png

http://img206.imageshack.us/img206/3656/64leds2mm7.png

MP:
Are you sure the teacher didn't say "timing diagram" and not "truth table"? 4017 is a decade counter.

MP

bobleny:
I know he said truth table. What this whole thing is supposed to do is create the illusion of random lights turning on and off. So, he said to make a truth table to see how random it actually is......

So, maybe he meant "timing diagram", but I don't know what that is...

bobleny:
I don't know if it is even possible to draw a truth table for this!??

I've been thinking about it, and yeah, I'm not sure if it is possible. lol Well, at least I can't figure it out....

audioguru:
It is not difficult to make a chart of the sequences of the LEDs in the circuit.
A CD4017 steps forward one step each time its input goes positive. It makes one output go positive during a step.

Start the chart by resetting all the CD4017's so that each one has its "0" output high and that LED turned on. Then let the 555 oscillate which makes the "00" CD4017 step its sequence, and its outputs cause the CD4017's connected to its outputs to step through their sequences.