Jump to content
Electronics-Lab.com Community

what is noise??


Recommended Posts

Hi Eie,
If you switch between two inputs that have a different DC voltage, you will hear a "pop" noise, or see a flash on a video screen.
Even if you switch between two audio sources that are capacitively-coupled and are grounded by a resistor, if one signal is positive at the moment when you switch to another one that is negative, you will hear a "pop" noise. Digital switches have a "zero-crossing" circuit to eliminate the pop.
If you use a switch that is designed to switch a high mains current and has silver contacts that corrode, to switch low-level audio or video, then you will either get nothing or a lot of crackling noise and distortion. Switches with gold contacts (at very little extra cost) are designed for that application. Switches are also made with bifurcated contacts or with a wiping action (self-cleaning) for low-noise.

Of course ICs have noise. If you use an old general purpose one like a 741 as a low-level microphone high-gain preamp, its output will have a constant "ssssssssssshhhhhhh" noise. If you use an IC that is designed for low-noise low-level audio or video, the noise will be so small you won't notice it.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


  • Create New...