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In Reply to: Plotting B-H curves posted by cjenrick on August 12, 2004 at 15:56:40:Cheap B-H loops.You can use a Variac and an isolation transformer to drive the part at 60 Hz. Use an RC set to 0.6 Hz or lower to make the B curve. The capacitor must be a polypropylene (not mylar, not aluminum). Use a resistor in the ground leg at less than 10% of the winding resistance to measure current and then look at the curve on a scope set to X-Y.Measure the voltage across the coil with an average (not true RMS) volt meter to get the saturation voltage of the B-H loop point you are testing. You need an average reading meter because saturation is average based issue, not true RMS based issue.Another interesting test is to drive the low voltage side from a 600 ohm signal generator and look at the primary voltage at different frequencies (beware, The primary side is a serious shock hazard.) This gives you an idea of what the magnetization current is doing to your signal.Play safe and play longer! Don't be an "OUCH!" casualty.Unplug it, discharge it and measure it (twice) before you touch it. . . .Oh!. . .Remember: Modifying things voids their warrantee.
CJ,70% calculation and about 30% 'get out some cores and wind some wire'. Charlie