My delta uses 100K NTC thermistors for the bed and hot end. In preparation for the PT1000 platinum hot end sensor, I flashed Marlin with the hot end sensor appropriately changed (from Type 5 to Type 1047). I then taped the sensor to the bed, and set the bed for 100C. It tracked quite nicely, but the reading "bounced" between readings about 3C. No way the heavy glass bed was doing that, so I soldered a 1000uF tantalum cap as close as I could get it to the control board microprocessor.
Problem solved.
