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).
Proposing a test for electrical contacts in high-frequency circuits, such as ignition and radio systems.
| Identifier | ExFiles\Box 52\3\ Scan089 | |
| Date | 11th June 1923 | |
| X4430 To R & E. {Mr Elliott - Chief Engineer} from EFC. {E. Fowler Clarke - Electrical Engineer} c. CJ. & PN. {Mr Northey} c. BY. {R.W. Bailey - Chief Engineer} EP. {G. Eric Platford - Chief Quality Engineer} HM. {Capt. W. Hallam - Head Repairs} WOR. {Arthur Wormald - General Works Manager} EFC {E. Fowler Clarke - Electrical Engineer} 2/T11.6.23. X.4054 - RE ELECTRICAL CONTACTS. X.4430. Electrical contacts through which have to pass high frequency currents such as exist in ignition systems, particularly in the circuit comprising the condenser and the contact points, and in radio circuits, appear from experiments, to need to be more definite or positive than contacts for direct or low frequency alternating currents. We have had instances of this phenomenon, both in ignition and in radio work. A test for the goodness of an electrical contact is suggested from this latter class of work. The contact under test is included in an oscillatory circuit in which a high frequency oscillation is sustained through the agency of an ordinary radio valve. Any variations of resistance in this oscillatory circuit will cause a modulation (or variation of amplitude of the high frequency oscillation) which modulation can readily be detected by one of the usual detecting devices and made audible in a telephone ear-piece. There is also the advantage that a complete condenser of any practical capacity can be included in such a circuit for the purpose of testing the connections thereto. If all the connections in the oscillator, circuit are sound, there is no audible noise, but wi a spring | ||