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).
Suggested scheme of windings for an outside primary ignition coil design.
| Identifier | ExFiles\Box 164\5\ img095 | |
| Date | 10th November 1931 guessed | |
| SUGGESTED SCHEME OF WINDINGS FOR R.R. DESIGN OF OUTSIDE PRIMARY IGNITION COIL. Primary. 400 turns of 23 S.W.G. S.C.C. enamelled wire Length of mean turn 6.00" Approx. resistance cold 3.60 ohms. Watts dissipation 40.2 Secondary. 20,000 turns 42 S.W.G. wire Iron circuit. Core dia. .500" made spiral construction by winding up a long strip of "Lohys" iron .012" thick. Over the outside of the primary 10 turns of "Lohys" also spirally wound. A 3 B.A. iron bolt through centre could be securing bolt and winding mandril for winding up the core. Case. Thin gauge iron with a joint or seam. The case could be ventilated with advantage at the top. Only one paxolin tube would be used - that over the core. Two or three turns of oil silk over the primary would insulate it from the outside iron sheath. | ||