1-in-4 sequencer freezes up--a noise problem?

Dear Ed, Thanks for the "hot tips"--I'll try the diode and 470 uF cap when I get back to Fresno. Also, Jasen, sorry for the seasonal confusion. Yes, I do mean THAT sort of Christmas tree. I think you can now view my Christmas tree (and ALL the "trimmings") at:

Bruce

Dear Ed,

I GOT IT! I tried your suggestions (diode and 470uF cap) and did not find success, but when I put 470 uF caps across all three chips (CD4013 & CD4001, as well as the 555) I got some improvement. The new problem that surfaced was that it would go to the bottom light (green) and trigger the circuit, but then continue on back to the top amber light. So the green light would consistently trigger the computer clock to start timing, but if a racer blinked, they'd not see that the green light had been ON--since the top amber light light is the one that stayed on. I figured that the 470 cap on the 555 was holding so much charge that it allowed the 555 to get one more clock pulse to be delivered, even after the power to the 555 was shut off. That may not be a correct analysis, but in any case, when I removed the 470 cap from the 555 timer, it worked flawlessly (stopping with green light ON) 30 times in a row. I assume that means it works "consistently". Thanks for inspiring me to fiddle with the circuit. Sorry about never getting pictures of my circuits posted for people to see--I had two trojan viruses that attacked last week, and some other frustrations in trying to get my pictures posted on the net. I know that should be a simple thing, but I never succeeded in doing it.

Thanks again for your help, Bruce

Did you bypass the supply on all the chips with .01 uf caps from + to ground, physically near each chip? If not, do so.

Ed

Dear Ed, Yes, I did do that, initially, but it didn't do the trick. In any case, it tis working now : ) Bruce.

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Thanks to all you who helped me along the way to my eventual success. With everything else you know, perhaps you'd know someone who'd like my extra copy of Rudolph Graf's Encyclopedia of Electronic Circuits, Volume 6. I'm in Fresno, will ship anywhere in USA. Bruce