_____________________________________________________________________ Special Amplifiers
7-125. Figure 7-35 shows a simple half-wave magnetic amplifier. This is a half-wave
magnetic amplifier because it uses a half-wave rectifier. During the first half cycle of the
load voltage, the diode conducts and the load windings develop load flux (shown in view
(A) by the dashed-line arrows) The load flux from the two load coils cancels and has no
effect on the control flux. During the second half cycle, the diode does not conduct and the
load coils develop no flux (shown in view (B)). The load flux never has to reverse direction
as it did in the saturable-core reactor, so the hysteresis loss is eliminated.
7-126. Figure 7-35 shows the circuit that is able to use only half of the load voltage (and
therefore half the possible load power) since the diode blocks current during half the load-
voltage cycle. A full-wave rectifier used in place of CR1 would allow current flow during
the entire cycle of load voltage while still preventing hysteresis loss.
Figure 7-35. Simple Half-wave Magnetic Amplifier
23 June 2005