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15 May 2016

8th Nov 1946: family cremation... electronic discovery

8 Fri. Very cold, very dull; bitter NE wind. Did all the usual week-end shopping locally, also bought cats’ meat at Morden.

Uncle Will’s remains were cremated to-day; it was his wish. Only Dad, Aunt Liza and Uncle Ben remain of the family now. Uncle Will was a forceful personality and abounding in self-confidence. He was devoted to his wife whom we rarely see and they now live at Romford.


Experimenting with a tapped secondary output transformer. I discovered the cause of transformer distortion*. An out-of-phase effect is set up in high-amplitude frequencies due to the secondary being influence by the magnetic field of the centre core. The secondary should have currents induced in it from the outer poles of the core only. The secondary should be separated from the primary and wound as close to the outer poles as possible. I have made a note of it as I regard this as a discovery of great importance.


* Note: For most transformers, core saturation is a very undesirable effect, and it is avoided through good design: engineering the windings and core so that magnetic flux densities remain well below the saturation levels. This ensures that the relationship between mmf and Φ is more linear throughout the flux cycle, which is good because it makes for less distortion in the magnetization current waveform. Also, engineering the core for low flux densities provides a safe margin between the normal flux peaks and the core saturation limits to accommodate occasional, abnormal conditions such as frequency variation and DC offset.
Quoted from and acknowledged to: http://www.allaboutcircuits.com/textbook/alternating-current/chpt-9/practical-considerations-transformers

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