help me with 555

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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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:

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