fantastic... i had the same "skipping step 7" issue with my gate sequencer
a while back and had actually given up... swapping in a TL072 did the trick.
another project rescued from the "shelf of failure".
thanks!
bbob
on 3/20/05 9:26 AM, cgs_synth@yahoogroups.com at cgs_synth@yahoogroups.com
wrote:
a while back and had actually given up... swapping in a TL072 did the trick.
another project rescued from the "shelf of failure".
thanks!
bbob
on 3/20/05 9:26 AM, cgs_synth@yahoogroups.com at cgs_synth@yahoogroups.com
wrote:
> Message: 3
> Date: Sun, 20 Mar 2005 06:54:39 -0000
> From: "peng3002" <peng3002@...>
> Subject: Gate Sequencer funny behavior and different chips
>
>
> I got the main sequencer board soldered up. Powered it up and weird
> things started happening. Output 3 permanantly on, output 4 never
> turns on, and output seven is skipped (by skipped I mean it jumps
> from out 6 to out 8 with not even a pause on 7). Thought what the...?
> After much head scratching I decided to breadboard the circuit. Just
> the 4017 and half the LM358. No reset or End Out circuitry. Fired it
> up and this time I got nothing on output 2 and output 7 is still
> skipped over. Hmm...I replaced the transistor (bad one) for output 2
> and that problem was fixed. Tried different chips: seven different
> Fairchild CD4017BCN all had the skipping output 7 problem. Out of ten
> Motorola MC14017BCP five worked perfectly. Problem solved, now all 8
> outputs work properly.
> Out of 17 chips I only have five good ones? I found this hard to
> believe, so I re-installed one of the bunk Fairchild chips and
> started swapping out different LM358s. I tried Fairchild and National
> brands, and also LM2904. No change. Then I tried a TL072. Fixed it!
> Then I tried TL082, BA4558,MC33077. All worked. It seemed any split
> supply opamp worked. With the LM358 replaced by a TL082, I started
> swapping out 4017s. Every one of the seventeen 4017s I have worked
> perfectly!
> Can anyone explain this ? I'm just starting to dig into CMOS stuff
> and this really threw me. A nice thing about this discovery is maybe
> I can finally get my Gated Comparator working properly since it
> exhibits the same kind of skipping behavior.
>
>
>
>
>
> ________________________________________________________________________
> ________________________________________________________________________
>