RF noise elimination
I put a chest freezer in my TV room near my computer.
When the freezer kicks on, the PC speakers make a loud pop. When it cycles off, the speakers pop even louder. Naturally, if the speakers are off, there isn't a pop. I switched the freezer power source to another outlet using an extension chord (on another breaker). It helped a little, but not much. I read that the pop could be from RF interference created by arcing in the freezer's compressor motor, and it can be mitigated with a suppressor or snubber circuit, which I understand is a combined capacitor and resistor. Like this: https://www.digikey.com/en/product-h...nubber-network That's where I stopped understanding. I have no idea what to get and where to install it. Taking apart the freezer and soldering in a couple components is not a problem, but I don't know what to get. Help appreciated. |
The easiest solution is making sure that the audio cable is as short as possible and moving it around some to try and stop the noise. I'm lazy so that's as far as I've ever gone. A discussion I happened to be reading yesterday mentioned that these little ferrite core clips were magic, they seem cheap enough and you can get them easy enough. https://www.cablechick.com.au/cables...ml#productTab3 is the one they were discussing in particular.
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May or may not work, I use to fix similar noise on my cheap car stereo system by twisting the cables.
The cable itself just twist it. The goal is to do a similar loop, the more, the more efficient it will be. You can also use ferrite core noise suppressors: https://th.bing.com/th/id/R.9c0cf931...pid=ImgRaw&r=0 https://tse3.mm.bing.net/th/id/OIP.9...r=1.25&pid=1.7 |
Thanks a lot you guys.
I'm pretty sure the pop is caused by the opening of the contacts in the thermostat since it's loudest when the freezer clicks off. Since I moved the freezer to another room, the noise is not as loud, but it's still annoying as shit. I have an old cable with a ferrite clip molded onto it; I could swap that in just to try. I'm really want to try a snubber circuit, but I just don't know which one to get... |
You might also want to try powering your speaker amp through a common mode choke, see if you can't isolate the issue to speaker leads vs. the common AC supply (all your breakers are connected to the same bus, there is no isolation as standard for high freq noise).
That said if the freezer is riiiiight next to the speakers, then yeah EMI from the compressor motor clicking on (i.e. coils energizing or the B field collapsing when the motor turns off) can for sure be the culprit. A shielded lead form amp to speaker would be your next bet there IMO. |
You connect the snubber electrically across the contacts that open.
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Wanted to come back and close this out. I got a snubber circuit from ebay for $1.59 and wired it as Jason suggested. It has worked perfectly now for a few months. Nothing else seemed to work. Thanks for the help.
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Originally Posted by maplewood
(Post 1624236)
The easiest solution is making sure that the audio cable is as short as possible and moving it around some to try and stop the noise. I'm lazy so that's as far as I've ever gone. A discussion I happened to be reading yesterday mentioned that these little ferrite core clips were magic, they seem cheap enough and you can get them easy enough. https://www.cablechick.com.au/cables...ml#productTab3 is the one they were discussing in particular.
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Thank you so much for the information, I am going to buy it.
Spoiler
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