Electronics > Beginners
RF filter from audiophool to realety.
<< < (3/5) > >>
helius:
I guess it would be interesting to plug a power quality analyzer from Yokogawa or Dranetz into this thing and see what kind of difference it makes.
There are many sources of conducted interference and the best filter for one type is different from another.
FriedMule:
T3sl4co1l you are completely correct! :-)

To answer your questions: Mr. EEV and others are often fighting with outside and inside noise, while testing or messeure electronic. EEV has build a noise free enclosure with 2 x 9V batteries, but for my purpose I need a lot more power. So therefore a noise filter that cleans main, before it delivers it to my project. So that any noise are from the project itself.
rstofer:

--- Quote from: helius on May 13, 2018, 09:15:08 pm ---
The idea of a "ground lift" is that if one of the interconnected devices' local grounds was allowed to float, it would follow the other device via the cable shield, keeping them at the same potential.

--- End quote ---

And if you unplug the device with the earth ground, all of the remaining equipment becomes ungrounded.  As I said, this practice seems dubious (to me).

The 'star' ground probably works better and, to some extent, we get this for free when we plug all the devices into a common power strip.  The shorter the power cords, the better.  Then we get the problem back again if the power requirements exceed the capability of a single branch circuit but that's at least 1200W in the US so I'm not sure if this ever happens.

Fiber optics is probably the best answer but the cost of converters (and the signal quality) may put this out of reach.
FriedMule:
Would the power cords not act as antennas for every signal?

I thought that a simple 100hz-3Ghz filter could be perfect for cleaning and then build it into a cast aluminium box?
rstofer:
They do make shielded power cords and even recommend cutting off the computer end to break out the shield as a 4th conductor.  At the equipment end, I would probably leave it unterminated.

http://www.slt.co/products/ShieldedPowerCords/ShieldedPowerCords-6Foot-12Foot.aspx

They may even make twisted cable but I didn't go look for it.  Of course, you could use any suitable cable as a power cord and Belden makes just about every conceivable cable.

3 GHz?  I thought the discussion was around audio, sorry about previous references to audio.  When I look at the OP, it mentions only a filter for the workbench.

I think T3sl4co1l's reply above about sums it up.  If you can't measure it, it doesn't exist.

We did use LC filters on the power coming into screen rooms, back in the day.  It was just a big, heavy, sealed box that hung on the side of the structure.  Power went in on one side and came out on the other.  I have no idea what was on the inside other than it generically being an LC filter.

In concept, they were a lot like these commercial units except they had enclosures over the connections suitable for conduit.

http://www.kemet.com/Lists/ProductCatalog/Attachments/718/KEM_EMI0002_FLLD4-TH.pdf

Power line conducted interference is only one source and may be the easiest to deal with.  Radiated interference is much harder to deal with and that's why we had screen rooms.  And no fluorescent lights...
Navigation
Message Index
Next page
Previous page
There was an error while thanking
Thanking...

Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod