Posted on Aug 23, 2012 10974
Full-wave control might be realized by the addition of a bridge rectifier, a pulse transformer, and by changing the thyristor from an SCR to a TRIAC, shown in Fig 50-9b. In this circuit, R 81 is not necessary since the pulse transformer isolates the thyristor gate from the steady-state UJT current. Occasionally, a circuit is required to provide constant output voltage regardless of line voltage changes. Adding potentiometer Pl to the circuits will provide an approximate solution to this problem. The potentiometer is adjusted to pro· vide reasonably constant output over the desired range of line voltage.