Redpitaya Forum

We've been running into issues with Red Pitayas generating substancial periodic switching noise trains shown below. The problem was most noticeable with the 1st generation of the USB power supplies that were included with RP. It almost disappeared with the second generation of the power supplies, but it re-appeared with the latest PS models supplied with the Red Pitayas. I can dig around the lab to look up the part numbers if you need them, we purchased a few dozen Read Pitayas over the years. Ii just run another test, red is noise induced by the Red Pitaya into DUT when powered by the wall wart PS supplied, blue is the exact same circuit, but now RP is powered by a high quality linear PS. Time is in seconds:



Zoomed-in burst:



How can we mitigate this problem with current breed of the included PS? Are there plans to provide high-quality 5V power supply in the future?

Just to be thorough, I rummaged through the cupboards and located a PS we used to get with RP few years back, Shen Zhen Keyu Power, Model KA23-050200DES, plugged it into RP and run the same test (blue waveform) against the currently supplied PS KA1201A-0502000DE (red waveform), and it is like night and day:

Hello, fbalakirev,

Thank you for reporting the issue; we appreciate it. We will test this and use better power supplies in the future.

Thank you for taking the time to report the power supply codes, this will help with the testing.

Hello,
I am afraid, that you will always get a loss of measurement quality by using a swith mode power supply. When I bought the RP in the past, I never spared a thought about using other than a linear regulated power supply. You have to imagine, that one quantize step is about 0.2 mV of the inputs.
Of course, there are a lot of quality differences amongst the switch mode power supplies. To suppress (not to say to eliminate) the common mode disturbances, many of them even do not use any bridge capacitors and/or drain the spikes to earth or filter it with ferrites -- this would be too expensive in comparison to the cheapness of their main functional construction.

Sorry to say, but I would recommend to use linear regulated power supplies only.

Best regards

Dieter