Tweakers' Asylum

Posted by Æ (A) on February 09, 2011 at 09:23:59

In Reply to: RE: That will just radiate the noise posted by Maxamillion on February 09, 2011 at 06:16:13

That's weird, because they use caps to suppress NOISE in all sorts of places. They use caps across rectifiers, they call them snubbers. They use caps across switching contacts, they call them sparking capacitors. They use caps across the contacts in car distributors, they call them "condensers." In fact if you DON'T use a capacitor you can hear the alternator/distributor whine through your car radio! Yes, I said hear. They use caps across the starter contacts in simple fluorescent light fixtures. They install caps across the brushes in many motors. My scale electric helicopter uses a simple DC motor to propel it and it has caps across the brushes/commutator to suppress radiated noise from interfering with the operation of the receiver, were talking about Radio Control and Radio Frequency Interference.
So, if what you are saying is true, then we should avoid caps in their entirety. But obviously we can't because caps serve a useful purpose and suppress all kinds of radiated noise.

I have an entire book on Radio Frequency Interference both receivers and transmitters and it recommends various bypass capacitors depending on the particular problem. It also recommends the use of chokes too.

Edits: 02/09/11