Design and construction details for a De Jon ignition coil.
| Identifier | ExFiles\Box 164\5\ img094 | |
| Date | 3rd November 1931 guessed | |
| PARTICULARS OF DESIGN AND METHOD OF CONSTRUCTION OF DE JON IGNITION COIL. (a) Iron Circuit. Consists of two parts, the inner core composed of 36 plates 3.200" x .410" x .016" together with an outside sheath consisting of 4 plates 3" x 3/4" x .013". The magnetic flux of the core is thereby mainly confined to the inside of the metallic coil case. Total weight of iron 8 1/2 ozs. (b) Primary Winding. This is on the outside next the case and consists of 404 turns of 25 S.W.G. plain enamelled wire of weight 3 1/4 ozs. wound in 6 layers with the following numbers of 82, 75, 71, 65, 57, 54. (c) Secondary winding. The actual length of this winding is 2.35" leaving a clear distance at each end of .400". It is wound on a paper tube over the core. The wire is enamelled copper wire .004" diameter. Weight of secondary wire 3 1/4 ozs. (d) Primary insulation. This appears to consist of .005" thickness of varnished paper between successive layers. (e) Secondary insulation. The interlayer insulation is .008" thick between the first and second and second and third layers (i.e. next to primary), the remaining layers consisting of .003" thickness except the last layer of insulation which is .009" thick. Material of the insulation appears to be a plain white paper impregnated with some bituminous compound. (f) General. Coil enclosed in .012" sheet metal case with soldered seam with top and bottom spun over and soldered. The core of the coil is supported in the case on a porcelain disc 1 1/2" dia. x 5/16" thick, this insulates the core, which is at H.T., from the coil case. A bakelite moulding with the top tin flange of the case apparently moulded in, holds the coil in position by means of a circular spigot extension which fits over the core at its top end, the H.T. terminal being in the centre of the moulding externally with the two L.T. primary terminals one on each side. | ||
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).