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Author Topic: moderately on topic...no RFI from new humidifier  (Read 916 times)

Offline IQ_imbalance

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moderately on topic...no RFI from new humidifier
« on: November 21, 2021, 1827 UTC »
Just purchased a small ultrasonic humidifier for my office since the desert-like humidity levels play havoc with my sinuses.  I was pleasantly surprised that the wall briquette and the device did not hash up my radios....at least the bits of HF, VHF, and UHF I'm currently monitoring. 

That is all!
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Re: moderately on topic...no RFI from new humidifier
« Reply #1 on: November 22, 2021, 0218 UTC »
Well that's certainly good news!

Nowadays I figured everything would generate RFI.

Offline RobRich

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Re: moderately on topic...no RFI from new humidifier
« Reply #2 on: November 22, 2021, 0538 UTC »
You might have gotten lucky with a decently filtered switching wall wart power supply. 8)

For those note so lucky, a good quick read on improving wall wart regulation and filtering:

http://www.dxing.info/equipment/wall_warts_bryant.dx
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Offline Ray Lalleu

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Re: moderately on topic...no RFI from new humidifier
« Reply #3 on: June 04, 2022, 2346 UTC »
You might have gotten lucky with a decently filtered switching wall wart power supply. 8)

For those note so lucky, a good quick read on improving wall wart regulation and filtering:

http://www.dxing.info/equipment/wall_warts_bryant.dx

Interesting reading, but quite outdated : it's about wall warts in the old way, with transformer on the 50/60 Hz mains frequency. Those old wallwarts were not so bad!

Nowadays, all wall warts are of the switching type : first, change the mains current to a high voltage continuous current, then use switching at some frequency between 30 and 120 kHz, where the transformer can be of light weight, then pass the output through diodes and (hopefully) capacitors. A switching PSU is a much more complex device, and can send HF noise on both the AC input and the DC output. The very bad ones are hardly producing 'DC' current, and can destroy the connected device rather quickly.
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