GB1100572A - Organ portamento system - Google Patents

Abstract

1,100,572. Electrophonic musical instruments. HAMMOND CORPORATION. 31 May. 1966 [15 June, 1965], No. 24178/66. Heading G5J. A portamento effect for an electronic organ is brought into operation when more than one contact associated with one or more playing keys is actuated. The organ consists of a number of transistor oscillators 10 the frequency of which varies with the potential applied to their base. All the oscillators are connected to a common line 46 to which the portamento voltage is applied and are connected selectively to the organ output by playing keys 28. Operation of a single playing key 28 to sound a particular note also closes one of portamento contacts 80 to generate a pulse which is differentiated by condenser 88 and resistor 90 to produce a sharp rise and a slow decay but which cannot pass transistor 72 because of clamp transistor 74. If two or more keys 28 and their associated portamento keys 80 are closed simultaneously, the pulse is able to pass the clamp transistor 72 thus depressing the oscillator frequency abruptly and allowing it to rise slowly in the manner of an Hawaiian guitar. The portamento effect is increased according to the number of keys pressed simultaneously but reaches a limit determined by diode 86. Releasing the keys discharges condenser 88 quickly through clamp 74. A vibrato signal may be also applied through a vibrato normal-vibrato small switch 44 but the portamento overrides the vibrato until the frequency of the oscillator is restored to normal. A single key may be provided with a number of contacts so that the portamento increases with pressure.