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Posted by Dave on October 12, 2008, 4:09 am
Hi !
If you are using a digital scope to look at waveforms, you may be suffering
from aliasing because the time/div is set wrongly - or another common
problem is probing a circuit without using the earth lead on the probe -
this would give you a line frequency injection of noise ...
Dave
E.persia wrote:
> hi every body
> I have a signal generator thak works with 555
> sometimes I see a a noise like digital FM that I think it from 50hz
> 220 (network voltage)
> what i can do to remove it I dont know even when it comes
> may be its the malfunction of breadboard
> but this my problem the output square wave wavelenght decrease and
> increase priodically!
> what i can i do for such a thing?
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> I have a signal generator thak works with 555
> sometimes I see a a noise like digital FM that I think it from 50hz
> 220 (network voltage)
> what i can do to remove it I dont know even when it comes
> may be its the malfunction of breadboard
> but this my problem the output square wave wavelenght decrease and
> increase priodically!
> what i can i do for such a thing?