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).
Ignition coil experiments, detailing the effects of reversing current direction on sparking characteristics.
| Identifier | ExFiles\Box 52\3\ Scan344 | |
| Date | 14th November 1919 | |
| Contd. -2- EFC {E. Fowler Clarke - Electrical Engineer} 1/T14.11.19. battery round or reversing the connections to the primary, there is an immediately difference in the sparking characteristics. There is no difference, however, brought about by changing the order of the various pieces of apparatus in the circuit without changing the direction of the current in the primary. Making use of a Remy 6 volt 12 cylinder coil which has both ends of its secondary winding insulated and brought out independently, we have proved by reversing the secondary in relation to the primary by connecting the high tension terminal to earth and using the earth connection as the high tension, that it is the direction of the high tension discharge only which affects the sparking characteristics. The effect of connecting the inside end of the secondary coil direct to earth or to different points of the primary circuit is quite unappreciable on the secondary spark. (There should be a slight effect due to whether the turns of the primary are added, subtracted, or neutral to the secondary winding, but this effect is too small to be observable). With the high tension discharge in one direction, the sparking on 5 mm. gaps in air is almost perfectly regular with the average coil. If, however, the direction of high tension discharge be reversed by changing over battery or primary winding, the mis-fires usually become rather pronounced. At the same time the sparks which do occur seem to be stronger and louder. In the former case, the running current can be reduced by the gradual insertion of resistance in the primary circuit to a very much greater extent without "putting the" sparks | ||