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RF Noise - Do you notice the RF noise floor has greatly increased with the influx of wall warts?

Cquk

I would be interested to see if any one else has noticed the issue. Maybe if you work on RF devices / have a spectrum analyiser etc.

Even some bench PSU's seem to produce more EMI than i would expect. 

I am working on adding Ferrite's to all my cables but where does it stop?

  • They are built cheap, not as a quality power product.

  • I suspect that a noisy supply would manifest itself in the form of amplitude modulation which could raise the noise near any RF tones you're creating.  It also wouldn't surprise me if you're seeing side bands at the frequency produced by the converter used inside the wall wart.  Often linear regulators will go a long way to clean some of this up.  One application area where the noise floor sufferers is if you have a log amp or something like that that doing wide-band detection.  In the past I found that particularly challenging in terms of elevated noise floor.

  • I also have had many problems with several cheap LED lamps.

  • If you can manage a spectrum analyzer, you can use it to identify the frequencies of the noise produced by different devices and power supplies.

  • in reply to bidrohini

    Of course. This was more an open ended question to see if others had noticed this and how they were approching it.

  • in reply to DAB

    100% the big problem is how do you identify a good quality vs bad quality at the time of purchase. It seems that compliance like CE is not being validated. Therefore you buy somthing and hope it works.

    I have seen products like bench supplies also fail to be as clean as you would expect.

  • in reply to javagoza

    Thats a good point. I did a lot of testing of these when they were first coming the mass market. The challange is there is not really enough space for good quality mains noise surpression. Add to this that a lot of dimmers where not designed for the load type presented by LEDs.

  • Just finished an emc seminar and they showed just that: the comparison between a "good" and a "bad" phone charger.

    Unfortunately you can't tell the difference just by looking at it.

  • in reply to javagoza
    javagoza said:
    cheap LED lamps

    Oh no kidding yeah. I bought some of those flower shaped garage lights and couldn’t even get the local radio channel. Other similar ones were fine though.

  • Good riddance.

    www.youtube.com/watch