Re: Any one tried living in a cave?
Posted by Karl on
URL: https://www.es-forum.com/Any-one-tried-living-in-a-cave-tp4031407p4031439.html
Plop Plop, if you want to block mains noise, you can use an AC low pass filter.
Most of them use some combination of common mode inductors and capacitors, and multi-stage filters often have one or more resistors to limit resonance.
Ideally you would want to block differential noise as well, but it's hard to do that on mains power because the high current saturates the inductors. This is the only manufacturer I've come across that tries, and you can see in their datasheets that they're only able to get 30-40 microhenries of inductance:
http://www.qualtekusa.com/products_chassis_mount_filters.php
You can also make your own filters, and in that case you can use toroids instead or E-shaped cores and make a few other tweaks.
I use pairs of small, low permeability toroids (Epcos B64290L0618X027) in parallel (2 on hot, 2 on neutral) for differential mode filtration because the math works out better. Still, that only gives me 1.9 millihenries and it saturates at less than one ampere, so I only use it to filter my computer and appliances. You're on 230V, so the saturation will be a little less of a problem, but still too low to filter a whole house.
For common mode chokes, I use a bifilar-wound high permeability toroid (Epcos B64290L0674X038) with 30 loops (counting both hot and neutral). I tried symmetrical winding at first because that gives you some differential inductance at high current levels, but the stray magnetic flux from the core is much worse. There's another type of winding that might be better, but I haven't tried it yet:
URL: https://www.es-forum.com/Any-one-tried-living-in-a-cave-tp4031407p4031439.html
Plop Plop, if you want to block mains noise, you can use an AC low pass filter.
Most of them use some combination of common mode inductors and capacitors, and multi-stage filters often have one or more resistors to limit resonance.
Ideally you would want to block differential noise as well, but it's hard to do that on mains power because the high current saturates the inductors. This is the only manufacturer I've come across that tries, and you can see in their datasheets that they're only able to get 30-40 microhenries of inductance:
http://www.qualtekusa.com/products_chassis_mount_filters.php
You can also make your own filters, and in that case you can use toroids instead or E-shaped cores and make a few other tweaks.
I use pairs of small, low permeability toroids (Epcos B64290L0618X027) in parallel (2 on hot, 2 on neutral) for differential mode filtration because the math works out better. Still, that only gives me 1.9 millihenries and it saturates at less than one ampere, so I only use it to filter my computer and appliances. You're on 230V, so the saturation will be a little less of a problem, but still too low to filter a whole house.
For common mode chokes, I use a bifilar-wound high permeability toroid (Epcos B64290L0674X038) with 30 loops (counting both hot and neutral). I tried symmetrical winding at first because that gives you some differential inductance at high current levels, but the stray magnetic flux from the core is much worse. There's another type of winding that might be better, but I haven't tried it yet:
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