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 function of an ignition coil with external resistance for a 6-cylinder engine.
| Identifier | ExFiles\Box 60\4\ Scan117 | |
| Date | 8th December 1931 guessed | |
| the correct ignition of a 6-cylinder running at 6000 r.p.m. On the other hand, ignition is still assured when, at the moment of starting, the feed voltage drops to one third of the nominal voltage, i.e. 4 volts for a 12-volt installation. Since the coil includes an external resistance playing the part of regulator, there is no need to make use of the American idea which consists in placing the primary outside the secondary winding (so as to permits its cooling in case the circuit remains closed when the engine stops. we are at your disposal for any further information you may require and remain, etc. | ||