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).
Comparative table of specifications for various ignition coils.
| Identifier | ExFiles\Box 164\5\ img373 | |
| Date | 29th June 1938 guessed | |
| SIMILAR TO D.75672 SECONDARY WDG. 15,000 TURNS OF 42 S.W.G. ENAM. COPPER WIRE. RESISTANCE 2810 OHMS AT 18°C. IMPEDANCE 8120 OHMS AT 18°C. INDUCTANCE 24-25 HENRIES. RR. AERO-COIL DC.277 WDGS TO D.7966. PRIMARY WDG. 384 TURNS OF 20 S.W.G. S.P. ENAM. COPPER WIRE. RESISTANCE 1.6 OHMS AT 20°C. IMPEDANCE 3.8 OHMS AT 20°C. INDUCTANCE .011 HENRIES. SECONDARY WDG. 15017 TURNS OF 42 S.W.G. ENAM. COPPER WIRE. RESISTANCE 2940 OHMS AT 20°C. IMPEDANCE 6680 OHMS AT 20°C. INDUCTANCE 19.1 HENRIES. DELCO-REMY COIL. PRIMARY WDG. DESIGN PARTICULARS UNKNOWN. RESISTANCE 3.57 OHMS AT 17.5°C. IMPEDANCE 6.81 OHMS AT 21°C. INDUCTANCE .01844 HENRIES. SECONDARY WDG. DESIGN PARTICULARS UNKNOWN. RESISTANCE 3970 OHMS AT 17.5°C. IMPEDANCE 16600 OHMS AT 21°C. INDUCTANCE 51.3 HENRIES. DELCO-REMY COIL WITHOUT BALLAST RR. COIL D.75260 RR. COIL D.72503 AERO-COIL DC.277 RR. COIL D.75672 DELCO-REMY COIL 240 280 EL 402 | ||