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).
Requesting the purchase of a Ferranti Rectifier type 253.P Alternating Current Milliammeter.
| Identifier | ExFiles\Box 165\3\ img074 | |
| Date | 12th March 1930 | |
| X975. s6033 To ROY{Sir Henry Royce} from EFC. EFC3/MG12.3.30 X.975 - ALTERNATING CURRENT MILLIAMMETER Will you please order, for the use of the Electrical Experimental Laboratory:- One - Ferranti Rectifier type 253.P Alternating Current Milliammeter with a 0-25 milliampere range. The Catalogue price is ................... £3. 0. 0d This type of instrument has only recently become available. Up to now we have made shift with a Dynamometer type instrument which absorbs 9 Volts for full scale deflection, and therefore is not properly suitable for measurements on secondary windings of ignition coils and Magnetos. The Rectifier type instrument is required: (1) As a more convenient and accurate instrument for the type of measurements to be made with it. (2) As a second instrument for similar duty to our present Dynamometer type A.C. instrument, which is in nearly continuous use, in conjunction with its external resistance, as an A.C.Voltmeter. EFC. | ||