paranormal activity of CMOS IC

[vinodquilon]

Look at two attachments...

In the circuit 4017 doesn't like its home place.

When I changed its place from circuit IC socket to a breadboard and fed its input &
supply directly from corresponding IC socket in PCB (by tapping upper socket pins through
simple wire strips) ,I got output at pin 1.

But when I return IC back to PCB socket from breadboard, I didn't get output at pin1!!!


I am sure there would be no problems with IC and socket. Also all inputs to 4017 was correctly
there.

Does there exist any interferences from neighboring components as 4017 is a CMOS IC ?

 

[karesz]

Hi Vinod,
I believe, that your only problem is the full missing of bypassings your both supplies! :-(
Pls apply on +5V & +12V (on both)an 10--100uF electrolytic/tantalum + on all your CMOS ICs an extra 100nF, but direct & so short as possible on the ICs...
You have surly other GND system on breadboard and PCB, these can be one more reason for some other behaviour.
Good luck!
K.

 

[vinodquilon]

Someone says it is due to 'cold solder joints'.
Some others care about 'missing of bypassing of supplies'.
Others are interested in 'floating inputs'.
I think by clearing all the above three cases, my problem would be solved. Thanks...

 

[karesz]

Hi,
They are all a possible source of your problem...
As Murphy told: past visited is the solution, or notihng is inpossible in live (or so)...
K.