Improved Phase Controlled Thyristor D.C. Power Supply

A simple method of reducing ripple in thyristor phase controlled d.c. power sources is described. Phase controlled power supplies are widely used in medium energy capacitor discharge systems using electrolytic capacitors. In the method outlined, the thyristor triggering is modified by the inclusion of a double time constant network in the unijunction transistor (UJT) trigger circuit. Reliability of triggering at low conduction angles is improved and the ripple is significantly reduced by this modification.