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).
Advice from Marconi's Wireless Telegraph Company on suppressing electrical interference from the dynamo and ignition systems.
| Identifier | ExFiles\Box 163\2\ img017 | |
| Date | 25th November 1932 | |
| TELEGRAPHIC ADDRESSES: Inland: EXPANSE, ESTRAND, LONDON. Foreign: EXPANSE, LONDON. CODES: MARCONI INTERNATIONAL, WESTERN UNION, BENTLEY'S, A.B.C. 5th & 6th Ed.{J. L. Edwards} LIEBER'S, SCOTT'S. TELEPHONE TEMPLE BAR 4321 (Private Branch Exchange) MARCONI'S WIRELESS TELEGRAPH COMPANY LIMITED. CONTRACTORS TO THE BRITISH AND FOREIGN GOVERNMENTS. Marconi House, Strand. London, W.C.2. 25th November, 1932. PLEASE ADDRESS THE COMPANY AND REFER TO [STAMP: ENGINEERING DEPT. No. E/A 7312] [HANDWRITTEN: 86008] Rolls-Royce, Ltd., Derby. [HANDWRITTEN: WST] Dear Sirs, With further reference to your letter of the 16th inst., ref.Hs{Lord Ernest Hives - Chair}/Wst.9/MA, and our acknowledgment of the 17th, ref.E/A.{Mr Adams} 76753, we are now in a position to advise you as follows. Much depends upon the type of engine, ignition system and dynamo. The dynamo L.T. ripple does not generally radiate interference, but if the car battery is used to feed the wireless receiver, then trouble may be experienced from this source. If a choke is used in series with the L.T. charging leads it will be rather heavy, say, 9 or 10 lbs., and should have an inductance of something of the order of .0015 henry, when carrying, say, 16 amps. Interference from the dynamo, however, is likely to be more serious from sparking brushes when charging. This nuisance generally can be cured by connecting two 2 mfd. T.C.C. paper condensers in series across the dynamo brushes and earthing the centre point. Interference from the ignition system is a widely varying factor from one model engine to another. It may be that the engines in question have a dual ignition system, viz. coil and magneto. In some cases the use of a simple resistor unit at the plug end of the leads is sufficient to bring the noise down to a reasonable level, but it is better to use screened cable for the plug leads, screening to be earthed at each end. | ||