Kain Posted February 13, 2005 Report Share Posted February 13, 2005 Hello, recently I did some CMOS timer design and it was working fine until we tested it in combination with some other relays. When we did this it started bouncing like crazy, so I think it is typical example of industrial noise influence :-[. Now I tryed to deal with it by putting optocouplers in the trigering inputs. Well it didn't even come close to solving it... You can see on the chematics that the power supply separates them from the AC. Maybe I need some additional filtering against high frequency noise (using inductance) or so. Am I missing something in the overall, such as some input floating and picking up noise? ??? Quote Link to comment Share on other sites More sharing options...
Kain Posted February 16, 2005 Author Report Share Posted February 16, 2005 Ok, here is the big no no I did on the PCB - I have traces passing between the pins of the ICs... Don't comment me pls ;D. The other thing is that some of the traces (I just didn't want to say all :-[) are pretty long for CMOS based circuit. And the really big no no was powering them up at 5V in the presense of industrial noise. At this voltage the noise to signal ratio is just bad (according to what I read 2 days ago). I tryed now the same thing at 12V and they worked nicely. Here is the PCB so you can see my major screw ups ... Who said that it's time to redo the board ? ;D Quote Link to comment Share on other sites More sharing options...
MP Posted February 19, 2005 Report Share Posted February 19, 2005 You might start with using a double sided board and use the second layer as a ground plane. This will clean it up a lot without re-design.MP Quote Link to comment Share on other sites More sharing options...
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