Strange behaviour: Shelly 1 makes interference from Shelly dimmer 2 disappear

  • I know, the title sounds very weird. So here is what I'm seeing and I'd like to understand it. It's probably more about electrical engineering that about shellies, but anyway:

    My dimmer 2 is suddenly causing interferences in my external computer speakers - but only when my Shelly 1 relay is turned off. I'm assuming that the interference sound id produced either by the dimmer 2 itself or by the voltage transformer that sits between the dimmer and the 12V halogen lights. And I think it only occurs when the light is dimmer down.

    Although I'm not sure how exactly the dimmer/transformer creates the annoying sound in my speakers, I wouldn't be writing this post if that alone was happening. What puzzles me is that the interference goes away is I turn on a Shelly 1 that is sitting on the same circuit. As soon as I turn it off again, the interference comes back...

    Can anyone explain?

    P.S. The interference sounds like this (it's not very loud, so you'll probably need to turn up the volume to hear it).

  • if you configure the anti-flickering debounce option you can minimize or even completely avoid this interference. In my case I manage to only keep the interference between 80 and 90% of the total power.