From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Table of maximum voltage readings at different tapping points on a coil, with an accompanying analysis.
| Identifier | ExFiles\Box 69\2\ scan0010 | |
| Date | 22th May 1930 guessed | |
| -2- Tapping point on coil. Max. voltage with secondary discharging at 8000 v.{VIENNA} Max. voltage with secondary discharging at 9000 v.{VIENNA} Primary negative to primary positive. | 737 | 913 2nd layer of secondary to primary negative. | 892 | 897 4th layer of secondary to primary negative. | 897 6th layer to 2nd layer. | 918 6th layer to 4th layer. | 489 | 620 10th layer to 6th layer. | 871 | other readings over the scale 14th layer to 10th layer. | 881 18th layer to 14th layer. | 840 These results indicate the presence of abnormal voltages particularly on the first two layers of the secondary winding. Taking the voltage proportionately to the number of layers which is 60 secondary, i.e. the secondary layers vary very little in the number of turns, the approx. voltage from layer to layer would be 250 with a secondary discharge voltage of 8000, and 280 at 9000. EFC/HEW. | ||