New design Switch mode supplies do not even need shielding. Try dis-assembling a cell phone charger and see for yourself. In the old days, shielding and filtering was used but today they design the parts so they don't radiate. The primary method is to control the raise time of the signals so there is less RF energy in the signal. Next they might go with spread spectrum rather then constant frequency so the radiated power per Hz is very much reduced and finally the PCB can be designed so the traces carrying the signal are very poor antennas. Doing all of this requires specialist engineers and a lot of up front design effort and computer simulation but it saves a ton of manufacturing cost by not needing a metal shield or filters.
My guess is that there are already close to 30 active switch mode power supplies in your house. Are they killing you TV, Radio and WiFi? When I first studied SMPS I was a student in the 1970's and the ones we designed and built as a student projects were horrible. The technology has matured a lot, like I said to the point ware now they don't even need shielding. On Wed, Apr 25, 2018 at 8:20 AM, Jon Elson <el...@pico-systems.com> wrote: > On 04/25/2018 04:48 AM, Erik Christiansen wrote: > >> As mentioned upthread, a linear regulator wastes power. But cheap >> switchmode power supplies tend to radiate RF, and wipe out radio reception >> in my remote rural location. >> > It is possible to place switchmode supplies in shielded enclosures to > reduce radiated EMI as much as you want to. The power savings can be > enormous. If your DC bus voltage is VERY stable, then you can use linear > regulation with minimal loss. But, if the lights have to work when the > battery is being charged through being discharged, you can't be that > efficient. > > Jon > > ------------------------------------------------------------ > ------------------ > Check out the vibrant tech community on one of the world's most > engaging tech sites, Slashdot.org! http://sdm.link/slashdot > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > -- Chris Albertson Redondo Beach, California ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
