switches the transistor ON, and its emitter-to-collector saturation voltage
decreases to a point below the voltage of zener diode Z1. Zener diode Z1 therefore
blocks the flow of gate current in silicon controlled rectifiers SCR1 and SCR2
until the output voltage falls to a level which shuts OFF the base current of
transistor TR as previously explained. As the phase terminals of silicon
controlled rectifiers SCR1 and SCR2 become negative, the rectifiers are switched
OFF and they remain switched OFF until gate current is again restored. This field
current switching action is rapid enough to provide a level output voltage control.
SUMMARY. This lesson has covered the construction and operation of the
multioutput AC charging system. The fundamentals of current flow and magnetism
were reviewed along with transistors and diodes.
a. Specifically, the effects of voltage and current were analyzed to
b. Transistor and SCR operations were analyzed to explain the electronic
c. The exercise will reinforce the discussion which was basically
fundamental and necessary to learn the reasoning behind the testing and overhauling
procedures which will be discussed in the next lesson.
OS 010, 1-P24