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).
The design and performance of ignition coils, comparing coils with and without ballast resistance.
| Identifier | ExFiles\Box 163\7\ img111 | |
| Date | 1st October 1927 | |
| EFC4/T6.10.27. -3- Contd. may be the case (difficult to prove conclusively) but it certainly does not have anything like the effect of altering the mechanics of the contact breaker. Apparently this point would remove one objection to the use of the ignition coil without a ballast resistance (taking large current at low speed). I do not think I altogether like the idea of using the coil without a ballast resistance because it must necessarily be a more serious matter if the switch is inadvertently left on, and secondly you do not get the levelling up effect of the spark intensity at varying speeds with which we think there is some advantage. On the other hand, we think the principle of the coil with the H.T. on the core inside and the potentials gradually reducing to the outside where the primary is, is very right, and we think we have sometime ago expressed this view to Mr. Royce when you sent us over a coil of this type which we examined. EFC. | ||