Circuit Noise

Thread Starter

yasir_66

Joined Jun 25, 2009
71
I am having problem with my counter.
I works proper but when i hold it in hand then it becomes working when i place it on a table or anything it starts counting itself.
whats the problem?
plz help me
 

SgtWookie

Joined Jul 17, 2007
22,230
It appears that you have left the COUNT and RESET inputs "floating".

All CMOS inputs must be tied to either Vdd or ground, or problems like this can occur.

You could use individual 10k resistors from the COUNT and RESET pins to ground to avoid this problem.
 

Thread Starter

yasir_66

Joined Jun 25, 2009
71
i have added 555 clock to pin#12(count) & reset to vcc through 10k.
i still have problems like that.
help me plz
 

hgmjr

Joined Jan 28, 2005
9,027
i have added 555 clock to pin#12(count) & reset to vcc through 10k.
i still have problems like that.
help me plz
It might help things if you place another 0.1uFd bypass capacitor very close to the positive voltage terminal on the 4-bit counter.

Check your wiring. You need to keep interconnectin wires as short as plausible.

hgmjr
 

Thread Starter

yasir_66

Joined Jun 25, 2009
71
hello SIR,
I followed u & i added 0.1uf to the 4bit counter(14553) on vcc but i am suffering same problem.
plz help me
 

bertus

Joined Apr 5, 2008
22,270
Hello,

Do you also have a 0.1 uF capacitor on the power lines of the NE555?
Is there a 0.1 uF capacitor on pin 5 (control voltage) to ground of the NE555?

Greetings,
Bertus
 

Thread Starter

yasir_66

Joined Jun 25, 2009
71
i observe that whenever i touch any soldering point my counter becomes normal & when i dnt touch then i becomes abnormal & counts itself.
what does it mean of touching my finger to any soldering point?
 

Audioguru

Joined Dec 20, 2007
11,248
A 555 oscillator causes 400mA current spikes on its power supply. That is enough to kill any counter circuit operating off the same supply.
 

hgmjr

Joined Jan 28, 2005
9,027
Greetings yasir_666,

I have merged all your related and scattered threads into the original thread.

In the future, please keep related replies and requests for information in the same thread. Splitting them up into multiple threads makes it hard for those members following the thread to keep track of the discussion.

Thanks,
hgmjr
 

bertus

Joined Apr 5, 2008
22,270
Hello,

Can you post a photo on how you have build you counter?
The touching behavour can be related to the way you made it.

Greetings,
Bertus
 
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