On Sunday, January 30, 2011 12:25:41 am Igor Chudov did opine: > Been reading the datasheet for the resolver: 11BRW-300-F10-10.pdf > > > http://igor.chudov.com/manuals/Harowe-Resolvers/11BRW-300-F10-10.pdf > > It calls for input voltage of 12 volts. I think that I give it much less > than that, 4.7 volts or so. > > This could explain why things are bad in every quadrant, when sine and > cosine together are only 50% of 4.7/sqrt( 2 ). > > Still trying to make sense of it, but I think I need more voltage on > input. One comment I was remiss in not making before this, Igor. The ac/dc conversions in many meters are "absolute value" amps as that gives a much more linear scale at low voltages, but are quite slow in terms of frequency response vs accuracy. At 400 hertz I would expect the average $150 DVM, particularly those that claim true rms readings, is going to be off, and off a long ways, reading way low. At 400 hertz, and a known 10 volts rms input, I have had some that would indicate that at well under a volt.
This I think, is where you either need a well calibrated scope, or believe it or not, one of the cheapest analog meters they sell. Those will have nothing more complex than a cheap diode to rectify the ac and give you an average reading that for a sine wave input, will be pretty close if the range switch is set so the reading is in the top half of the scale, and do it just as well at 400hertz, or even 2500 hertz as that data sheet indicates. No digital dvm I have ever had and that is quite a lengthy list over the years, could ever think of working at frequencies above 60 hertz and meet the nameplate 2% or 3% accuracy claimed. So I think, if I didn't have a scope, or I could question my scope, I'd go get the $7 pocket meter from the shack & pray the meter isn't too sticky. -- Cheers, Gene "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) <http://tinyurl.com/ddg5bz> A bore is a man who talks so much about himself that you can't talk about yourself. ------------------------------------------------------------------------------ Special Offer-- Download ArcSight Logger for FREE (a $49 USD value)! Finally, a world-class log management solution at an even better price-free! Download using promo code Free_Logger_4_Dev2Dev. Offer expires February 28th, so secure your free ArcSight Logger TODAY! http://p.sf.net/sfu/arcsight-sfd2d _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
