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).
Harmonic tests of buzzer type horns.
Identifier | ExFiles\Box 59\3\ Scan107 | |
Date | 9th January 1931 | |
X6031 COPY. AD.80. 9th January, 1931. X.6077/8 X.6031 X.6075. HARMONIC TESTS OF BUZZER TYPE HORNS. We have now made some tests for the presence of harmonics in a Bosch UKR. and a UK.12A horn and a Klaxon buzzer type horn using a piano as a calibrated resonator. The front of the piano was removed and the respective horns blown whilst the damper or a selection of them were lifted. A considerable range of strings responded, probably owing to forced vibrations set up in the sounding board behind them, but certain strings could be picked out from the rest as specially responsive. The horns were all of approximately 300 vibrations per second fundamental pitch, but the exact pitch could be sufficiently adjusted by varying the working voltage. The harmonics observed in the three horns were as follows : Bosch UK.12 (earlier type). Moderately strong third harmonic, also a fairly strong eighth. Bosch UK.12A (later type). A more powerful fundamental than the UK.12. No very marked harmonics. Klaxon. (Two-tone type used, working on high tone.) A strong third harmonic and a very strong twelfth. These results confirm the view that the Bosch is characterised by purity of the fundamental. We think that the strong twelfth in the Klaxon accounts for its characteristic quality. RJA. | ||