HI all,
I've been having problems with a timer circuit I'm building. It uses a chai n of seven CD4017BE decade counters. The first in the chain gets clock puls es from a 555 running at about 10Hz. I take the last output from this chip (puts out one pulse for every 10 input pulses) and feed it to the input of the next chip where the same thing is done and so on so the pulses get time
-divided by 10 at each stage. All's fine up to decade 4, then something odd happens. Instead of just pulsing, the output goes high and remains high un til the next pulse comes along and toggles it back to low, so this stage's output is high for far too long. For this prototype I'm using rat's nest on PCB construction and believe I'v e paid proper attention to grounding and decoupling. Funny thing is, if I t ransfer the components over to proto-board, the problem disappears. Do thes e symptoms ring a bell with anyone? Is the 4017 particularly layout-sensiti ve? It's driving me nuts.
TIA