4017 strange output level - Page 2 - Electronic Circuits Projects Diagrams Free

**mechie** · 10th July 2003, 10:30 AM

Pebe's circuit description is correct, and there is no need for any resistors.

What is the input to this circuit :?:

If you are using, say, a pushbutton and when released the input is just floating...
CMOS is so sensitive it could be picking up an input capacitively from an output, causing the 4017 to 'race', trying to count faster than is reliable, and giving unpredictable results.

Contradicting what I said above :? try a 100k resistor from 0v to the 4017 input, see if that calms it down.
NOTE:- I think 100k to 1MEG should be OK for CMOS, enough without loading the outputs too much. 10k or less is starting to get too heavy in my experience.

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10th July 2003, 10:30 AM	(permalink)
mechie	Try this Pebe's circuit description is correct, and there is no need for any resistors. What is the input to this circuit :?: If you are using, say, a pushbutton and when released the input is just floating... CMOS is so sensitive it could be picking up an input capacitively from an output, causing the 4017 to 'race', trying to count faster than is reliable, and giving unpredictable results. Contradicting what I said above :? try a 100k resistor from 0v to the 4017 input, see if that calms it down. NOTE:- I think 100k to 1MEG should be OK for CMOS, enough without loading the outputs too much. 10k or less is starting to get too heavy in my experience. __________________ I need a memory upgrade ... My head is full !