good point, Gary. Only the front end of the switcher would see the different input voltage and frequency. The high-speed oscillators on the motherboards, etc., should not be affected by input voltage/frequency, yes?
Dwight Gary McInturff wrote: > > That's interesting. The change from 50 to 60 Hz would change some input > components and that could effect the input impedance and hence the > conducted emissions signature but the voltage, especially if its a well > regulated and filtered supply should be invisible. The components that > radiate at that point are all of the secondary 5 or 3.3 volt oscillators > and stuff. They shouldn't even know the difference in the input voltage. > If using a switcher power supply it seems even more odd. The input > voltage is rectified and then chopped to "#$@ then more regulating and > filtering stuff happens. Then it hits the electronics. > Anybody else see this and have an idea why it might. I may be living in > a fools paradise here. > Gary McInturff > Packet Engines > > -----Original Message----- > From: hmellb...@aol.com [SMTP:hmellb...@aol.com] > Sent: Monday, July 06, 1998 11:16 AM > To: dwight.hunnic...@vina-tech.com; emc-p...@ieee.org > Cc: eric.lif...@natinst.com > Subject: Re: Ce versus FCC > > I have encountered certain European agencies requesting that not > only are the > conducted emissions required to be performed at 230V 50Hz but > radiated > emissions as well. I agree that for conducted emissions it may > make a > difference but I have not seen radiated emissions change when > the power source > is changed from 60 to 50 Hz (while keeping Voltage the same). I > did, however, > see recently a product change emissions when the voltage was > changed from 120 > to 230 V. And, it did not matter if it was 50 or 60 Hz, only the > voltage was > significant. Go figure! > Hans -- DWIGHT HUNNICUTT Sr. Compliance Engineer **************************** * <dwi...@vina-tech.com> * * (510) 413-1349 direct * * (510) 492-0808 fax * * VINA Technologies,Inc. * * 42709 Lawrence Place * * Fremont, CA 94538 * ****************************
