S_SHAPED_RAMP

Published:2009/7/15 22:08:00 Author:Jessie | From:SeekIC

Developed for 60-Hz vertical deflection in high-resolution video display requiring highly linear ramp summed with second integral of ramp to give S shaping of deflection so sweep is linear on flat screen. Opamp A1 is connected as integrator that takes integral of constant voltage across zener D1. Period of integration is limited by UJT Q1 that resets integrating capacitor C1 when negative-going sync signal is applied to base 2 of Q1. Sawtooth linearity can be trimmed by adjusting ratio of R.4 to R5. Sync range is wide enough so external vertical hold can be eliminated. Amount of shaping can be adjusted with pot.-L. G. Smeins, S -Shaped Sawtooth Oscillator, EDN Magazine, Feb. 20, 1974, p 83 and 85.



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