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).
Table of finally approved windings for a green lamp switch and auto charge control switch.
| Identifier | ExFiles\Box 60\3\ Scan055 | |
| Date | 12th June 1928 | |
| X4040 12.6.28. TABLE OF FINALLY APPROVED WINDINGS FOR GREEN LAMP SWITCH AND AUTO CHARGE CONTROL SWITCH. X4008 Armature bobbin. | Pivot bobbin. R.R.12. volt Green lamp switch. | Fill up with 28 S.W.G. D.S.C. copper wire. | Fill up with 24 S.W.G. D.C.C. Manganin wire. R.R. 12 volt Auto charge Control Switch. | As above, with 28 S.W.G. D.S.C. Copper wire. | As above, but one layer less of 24 S.W.G. D.C.C.Manganin wire. Field resistance winding 12 feet of 30 S.W.G. D.C.C. Eureka wire. R.R. U.S.A. 6 volt auto charge control switch. | Fill up with 24 S.W.G. D.S.C. copper wire. | Fill all but one layer with two 24 S.W.G. D.C.C. Eureka wires in parallel. Field resistance winding: 6 feet of 26 S.W.G. D.C.C. Eureka wire. EFC. | ||