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 the quality of electrical contacts carrying high-frequency currents using an oscillatory circuit.
| Identifier | WestWitteringFiles\K\June1923\ Scan43 | |
| Date | 11th August 1923 | |
| To R & E.{Mr Elliott - Chief Engineer} from EFC. c. C.J. & F.H. c. Hy{Tom Haldenby - Plant Engineer} & EF. c. RG.{Mr Rowledge} c. HJT. ORIGINAL EFC2/T11.8.23. X.4054 - RE ELECTRICAL CONTACTS. 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 a spring contact in the circuit will cause more or less noise when disturbed in any way (without the connection actually being broken) Contd. | ||