Importance

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Abstract

A manually operable pulse generating apparatus comprises a dial knob assembly having a outer grippable knob member rotatably mounted around an inner knob member connected to an operating shaft carrying a ratchet wheel-forming cam having saw-toothed ratchet teeth-forming lobes. Each lobe has a gradually rising leading side and a sharply dropping trailing side. The outer knob member is connected to the inner knob member through a one-way clutch so that the outer knob member can be rotated in one direction without rotating the inner knob member, the inner knob member rotating with the outer knob member when rotated in the opposite direction. Where the outer knob member is opaque, it contains numbered markings for identifying the degree of rotation imparted thereto relative to a stationary index mark on a control panel over which the dial knob assembly is mounted. For some applications, the outer knob member may be transparent in which case the numbered markings referred to are on the inner knob member. A pawl-forming, force-transmitting spring or spring-urged member normally rests in the crotch between successive ratchet teeth-forming lobes of the cam where it is in a partially tensed condition to form a detent for the shaft. The rotation of the outer knob member in said other direction rotates the cam and causes the pawl to ride up the gradually rising side of a cam lobe so that the tension in the pawl initially slowly increases. The tension on the spring or spring-urged member is coupled to a piezo-electric element which generates a damped sine waveform as the tension thereon is suddenly relieved as the end of the pawl falls into the crotch between a pair of cam lobes.

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First Claim