GB653102A - Improvements in or relating to pulse generating apparatus - Google Patents

Abstract

653,102. Supersonic inspection devices. SPERRY PRODUCTS, Inc. June 30, 1948, No. 17570. Convention date, July 5, 1947. [Class 118 (ii)] [Also in Group XL (c)] A damped oscillatory pulse of relatively long duration is cut short by applying a shortduration pulse to a device which short-circuits the tuned circuit of the oscillation generator. A damped oscillation is periodically generated in a resonant circuit at 10 and is fed through a condenser to a load circuit, e.g. a piezo-crystal vibrator 12. The output from 10 is also fed to a delay network 31 and synchronizes a pulse generator 30 which gives delayed short pulses of a duration about equal to half the oscillatory period and applies them positively to the grid of a triode valve 15 connected across the generator 10. These pulses cause the valve to operate as a short-circuit, and cut short the damped train of oscillations. The crystal 12 may be used to transmit vibrations to a test specimen 14, irregularities in which will reflect the vibrations to an amplifier 35, the position of the irregularity being indicated on an oscilloscope 40 as in Specification 641,095.