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THE BELL SYSTEM TECHNICAL JOURNAL, JULY 1954 



described earlier (Diode IV, Fig. 2), a reference voltage diode (Diode 

 I, Fig. 2), two 50-milli\vatt, and two 2-watt junction transistors. 



The dc output voltage of the rectifier is controlled by a high gain self 

 saturating magnetic amplifier. High gain in the magnetic amplifier is 

 achieved by using tapewound gapless nickel-iron cores having rectangu- 

 lar hysteresis loops. The control current for the magnetic amplifier is 

 provided by 2, 2-watt n-p-n transistors acting in push-pull. The 2-watt 

 transistors are driven by 2, 50-milliwatt p-n-p transistors also acting in 

 push-pull. The circuit is similar to Fig. 21. Again, the reference potential 

 is furnished by a reference voltage diode. 



Where the rectifier is connected to storage batteries an additional 

 feature kno^vn as "current droop" is needed to protect the rectifier. The 

 output characteristic of the rectifier ^^dth current droop is sho^Mi in 

 Fig. 23. This characteristic is obtained by coupling a signal proportional 

 to load into the first stage transistor amplifier through a gating circuit. 

 This signal is provided by a dc current transformer which is another 

 form of magnetic amplifier. At currents below the "droop" value the 

 current signal is blocked from the amplifier. At full load the gating cir- 

 cuit allows the current signal to take over and hold the output current 

 constant over a wide range of output voltage. In Fig. 23, the performance 



60 80 100 120 140 160 180 200 220 240 

 LOAD CURRENT IN AMPERES 



Fig. 23 — Output characteristics of experimental 65-volt 200-ampere ger- 

 manium rectifier. 



