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).
Graph showing the volt-ampere characteristics for four different types of double ballast resistances.
| Identifier | ExFiles\Box 168a\5\ img014 | |
| Date | 3rd September 1929 | |
| VOLT-AMPERE CHARACTERISTICS OF DOUBLE BALLAST RESISTANCES. AMPERES. VOLTS. A - 34" of 34 SWG WIRE B - 39" . 33 . " C - 44" . 32 . " D - 50" . 31 . " -STD. GAUGE X.F.A.D. 3.9.29 | ||