Products > Test Equipment
Measuring power supply ripple with Siglent 1202X-E
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tautech:

--- Quote from: Electro Fan on August 31, 2023, 10:23:40 pm ---Not sure what size your Siglent probe requires - tautech can probably help you determine that.

--- End quote ---
Mario has a SDS1202X-E supplied with PP215 probes and probe to BNC adapters.
These are a nominal 5mm tipped probe and these should fit (select 5mm size)
https://www.aliexpress.us/item/2255800926120810.html?
Caliaxy:
Have you tried turning your (presumably LED or fluorescent…) lights off?
BillyO:

--- Quote from: tautech on August 31, 2023, 10:00:25 pm ---BW limit .. should be used for PSU measurements.

--- End quote ---
Why?

This is one of those ancient things from a bygone era when the scopes got better than 20MHz BW but the equipment under test could not react to noise at higher frequencies.  This is a different time and ignoring HF PS noise can lead you to endless grief.


To the OP:
Turn off your PS and measure the noise.  See if any of that is being caused by something else.
tautech:

--- Quote from: BillyO on September 01, 2023, 12:51:55 am ---
--- Quote from: tautech on August 31, 2023, 10:00:25 pm ---BW limit .. should be used for PSU measurements.

--- End quote ---
Why?
--- End quote ---
I said:
BW limit and 1x probe should be used for PSU measurements.

The modern 1x probe is itself a BW filter to some 6-10MHz as its additional tip capacitance helps reduce noise.
Of course probing technique itself further determines what we might see as does if the PSU is linear or SMPS.

The OP's screenshots photos indicate something at 50+kHz plus lots of other random noise, some of which is expected at higher sensitivity settings when probing technique is suboptimal.
For his 20mV/div 10x probe setting the actual scope setting is 2mV/div and well within the region where all manner of noise gets displayed.

His PSU appears linear with a ripple and noise CV <1mV rating so at these levels probing technique is everything so to not get bogus results and with us timebase settings instead of ms settings for a linear PSU it's no wonder the man is confused when using a highly sensitive scope with a fine antenna probe based measuring system.

MarioBros69:
Thank you for your answers, when I receive another device I will put all your advice to the test, measure in X1 with 20Mhz and the source with a load and direct connection to the source terminals

The power supply is linear and I have tried turning off all the LED lights, I have even taken the power supply and the oscilloscope to the kitchen and I got the same result, it is as if that noise were in the electrical grid and will be amplified within supply transformers

The strangest thing is that with the power supply off I get the same noise level
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