Products > Test Equipment

Spikes and noise on Rigol DHO814

<< < (4/10) > >>

Fungus:

--- Quote from: eTobey on March 13, 2024, 09:15:25 am ---Just in my first post! I found the same frequency on the cable, and doing measures for this, got rid of that spikes quite a bit!

Did you actually read what i wrote, and looked at the pictures???

--- End quote ---

That doesn't prove anything.

It can be coming through the power supply from the mains.

eTobey:
I happily would try to investigate this, if you tell me how i could track the sourc of it.

ebastler:

--- Quote from: eTobey on March 13, 2024, 01:17:24 pm ---I happily would try to investigate this, if you tell me how i could track the sourc of it.

--- End quote ---

You could try and block interference on the primary (mains) side, before the power supply: Use a plug-in mains filter on the 230V side, or put ferrite cores on the 230V input cable instead of the 15V output. Or move the scope to a different mains phase (different room), or better yet to a friend's house, for comparative testing.

eTobey:
Shouldnt the powersupply filter this all out and not generate it either?

ebastler:

--- Quote from: eTobey on March 13, 2024, 06:33:57 pm ---Shouldnt the powersupply filter this all out and not generate it either?

--- End quote ---

It's not black and white...

All switching power supplies generate some level of switching noise on their outputs. (There is a reason why good laboratory power supplies, which you may want to use e.g. for sensitive analog prototype circuits, still use big fat transformers running at 50 or 60 Hz and linear regulators, rather than the much cheaper switchers.) The output of a switching supply does not have to be perfectly clean if the device that you power from it does some filtering of its own.

The power supply may or may not have some internal input filters. In any case it will suppress most of the incoming noise by charging a large capacitor, then chopping the voltage up again for transfomation. But it does not suppress 100% of the incoming noise: If a particularly nasty source of voltage spikes is operating on your mains, some of that may come through.

(A motor with bad interference suppression is a classical source of powerline interference. Very cheap switching supplies are a more modern, but rather common source. E.g. I originally used a cheap no-name 12V supply to power the LED light strips on my bench, and that created nasty interference spikes everywhere...)

Finding the source of interference signals, and the path how they couple into your measurements, is not an easy task. Small changes can have a big impact, and there may be influences which you are unaware of and/or which are outside of your control -- e.g. some device which only runs part of the time and which causes interference. Be diligent and systematic, and take good notes: short description what you did and changed, note what was connected to the scope, photos of shielding or probe arrangements, screenshots of scope data. You will track it down eventually!

Navigation

[0] Message Index

[#] Next page

[*] Previous page

There was an error while thanking
Thanking...
Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod