GB552033A - Improvements in or relating to electrical musical instruments - Google Patents

Abstract

552,033. Electrical musical instruments. ELECTRICAL RESEARCH PRODUCTS, Inc. Oct. 6, 1941, No. 12864. Convention date, Oct. 15, 1940. [Class 88 (ii)] An electrical musical instrument employing rotating tone generators 13 driven by a constant speed motor 18 is provided with means for changing the rotation speeds of the tone generators substantially instantaneously from one predetermined speed to another predetermined speed so that music can be transposed to sound in keys other than that in which it is written and played, said means comprising speed-changing mechanism interposed between the time generators and the driving motor and giving a number of fixed speed ratios appropriate to the different musical keys and control means for selecting one of the available speed ratios. As shown, the speed-changing mechanism comprises constantly meshed gear trains 1 ... 5 and electro-magnetic clutches 22 for effecting the drive between the pinions 3, 4, these clutches being controlled by switches 11 so arranged that not more than one switch can be in closed position at a time. The switches are disposed in key-control section 10 of the console 6, the manuals, pedals, stops and volume controls being schematically indicated at 7. The wheels 1, 5 may have 86 and 172 teeth respectively. For the major key C, the ratio of the revolutions of the wheel 5 to those of the wheel 1 may be 1, obtained by providing a wheel 2 with 53 teeth and wheels 3 and 4 with 20 and 40 teeth respectively. For major key G, with ratio 3/2, the wheel 2 will have 59 teeth and wheels 3 and 4 16 and 48 teeth respectively; and so on.