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).
Product specification and information sheet for Marconi-Ekco noise meters and accessories.
| Identifier | ExFiles\Box 138\2\ scan0189 | |
| Date | 1st December 1938 | |
| PAGE 1 NOISE METER, type TF{T. Fisher}397 SPECIFICATION. Noise Meter, TF{T. Fisher}500. RANGE. 50-110 phons. This corresponds with a range of 50 to 110 dB{Donald Bastow - Suspensions} when referred to a reference level of 0.0002 dyne per sq. cm. at 1,000 c.p.s. ACCURACY. ±2 phons on steady sounds. ±4 phons on impulsive sounds. FREQUENCY CHARACTERISTIC. Three alternative adjustments are provided :— (a) Flat. (b) 40 phons equal loudness contour. (c) 70 phons equal loudness contour. MICROPHONE. Piezo-electric non-directional type having an exceptionally wide frequency response. METER. The indicator system agrees approximately with the ear in regard to the rapidity of response. AMPLIFIER GAIN. An input signal of about 20 µV applied to the microphone socket will produce half scale deflection on the output meter at the 50 phon setting. BATTERIES. Unspillable 2-volt accumulator and 90-volt dry battery. CALIBRATION. Means are provided for restandardising the calibration at power supply frequencies. MOUNTING. The controls and meter are conveniently disposed on a vertical aluminium panel which is mounted in a welded aluminium case having a removable lid{A. J. Lidsey} and carrying handle. FINISH. Panel—Black crackle lacquer. Case—Grey cellulose enamel. DIMENSIONS. 12½" x 14½" x 8½" (over projections). 19" x 20" x 15" (approx.) packed. WEIGHT. 23 lbs. nett. 61 lbs. gross (approx.) packed. PRICE. See Price Index. Vibration Pick-Up Unit, TF{T. Fisher}481. FREQUENCY RANGE. 10 to 3,000 c.p.s. FREQUENCY CHARACTERISTIC. For constant amplitude, the voltage output is roughly proportional to the square of the frequency up to 3,000 c.p.s. which is the natural frequency of the unit. PROPORTIONALITY. The voltage output is very nearly proportional to the vibration acceleration up to approximately 1,000 c.p.s. SENSITIVITY. At 250 c.p.s. the output is approximately 0.25 volt per 0.001 inch of motion. PROBE. Duralumin prod 8½" long with hardened steel tip. The tip may be removed and screwed directly into the unit. CONNECTIONS. 8 feet of screened cable, terminated in a plug for connection to the Noise Meter. DIMENSIONS. 2½" diam. x ⅞". WEIGHT. 8 ounces ; with probe 11 ounces. MARCONI-EKCO INSTRUMENTS LTD., ELECTRA HOUSE, VICTORIA EMBANKMENT, LONDON, W.C. 2. Telephone: TEMple Bar 4321. PAGE 2 MARCONI-EKCO INSTRUMENTS LTD. ELECTRA HOUSE, VICTORIA EMBANKMENT, LONDON, W.C.2, ENGLAND. DECEMBER, 1938 Section Ind.-A-2 superseding APRIL, 1938 NOISE MEASUREMENT. Noise Meters, types TF{T. Fisher}500 and TF{T. Fisher}397 and Accessories. The measurement and comparison of noise and vibration is becoming of increasing importance particularly in relation to industrial and social psychology. The abatement of noise has definite beneficial effects on the health of individuals and on their efficiency, and the quantitative evaluation of noise is therefore of growing interest not only in factories and offices but to public authorities and such bodies as transport organisation. The Noise Meter is self-contained and portable, and is read directly in phons. Certain features—notably the type of rectifier circuit used—are based on the description of an instrument in a paper by Dr. A.{Mr Adams} H.{Arthur M. Hanbury - Head Complaints} Davies of the National Physical Laboratory. Particular care has been taken in the design to ensure an accurate indication of transient noises. The auxiliary apparatus available includes a piezo-electric Vibration Pick-Up which replaces the microphone when mechanical vibration is to be measured. For special purposes an Adjustable Tuning Unit is available by means of which noise of a particular frequency can be emphasised or suppressed. For individual wave analysis we recommend the Wave Analyser, type TF{T. Fisher}455. Some examples of the application of the Noise Meter and its accessories are given. Domestic Appliances. Sewing machines, vacuum cleaners, refrigerators, fans, etc. Transport. Noise from all types of vehicles, including the exhaust noises of internal combustion engines. Industrial. "Steady" sounds such as transformer hum, noise from motors and alternators, from shafting, lathes, milling machines and saws. "Impulsive" sounds, such as noise from rivetters, pneumatic drills, belting etc. Offices. Persistent sounds, such as noise in general offices, lifts, etc. Impulsive sounds, such as noise from typewriters, computing machines, etc. Technological. Determination of the effects of sound proofing and absorbing materials. Printed in England. | ||