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).
Test report detailing ignition coil secondary voltages under various conditions.
| Identifier | ExFiles\Box 165\5\ img107 | |
| Date | 17th July 1933 | |
| IGNITION COIL SECONDARY VOLTAGES. Coil under test :- coil filled with brown wax. Date :- 17/7/33 (1) Normal temperature maximum open-circuit voltage. DAMPING FACTOR | Primary Volts. | Battery Normal. | Battery Reversed. 784 | 10 | 15300 | *12000 792 | 8 | 13000 | 10300 (2) Maximum temperature open-circuit voltage. DAMPING FACTOR | Primary volts | Battery normal. | Battery Reversed. 376 | 10 | 10900 | 11100 408 | 8 | 9800 | 4000 (3) Maximum temperature working voltage. DAMPING FACTOR | Primary volts. | Battery normal. 1 meg. 1/2 meg. | Battery Reversed. 1 meg. 1/2 meg. - | 10 | 5700 | 3400 | - | - - | 8 | 4500 | 1600 | - | - Signed :- | ||