igure 2-4. Waveshape Inputs from Logic Cicuits to Major Drive Section.

TM 1-6125-259-30

figure 2-4. Waveshape Inputs from Logic Cicuits to Major Drive Section.

end of 120 degrees point

goes to zero and point

The waveshapes at points

and

are used to

goes Postive. Transistor Q405will now conduct

produce the composite waveshape for phase

reversing the direction of current flow in trans-

(points

and

produce Phase B, points

former T402 causing Transistor Q205 to cut off and

and

produce phase C). When the logic level of

transistor Q31 to conduct. When transistor Q204

point E is positive, transistor Q404 will conduct

conducts a circuit is completed through primary

through transformer T402 in such a direction that

the polarity dots will be positive. This positive will

winding (phase B) of transformer T1, through

transistor Q203 (turned on previously) to the 37 vdc

forward bias transistor Q205. At the same time the

power source. This condition will last for an ad-

logic level of point

is positive causing transistor

ditional 60 degrees (total 180 degrees at which time

Q401 to conduct through transformer T400 in such

point

goes to zero and point

goes positive

a direction that the ends opposite the polarity dots

causing transistor Q401 to conduct and transistor

will be positive. This positive will forward bias

Q400 to cut off which will reverse direction of

transistor Q200. We now have a complete circuit for

current flow in transformer T400. Transistor Q201

current to flow through transistor Q205, through

will conduct and transistor Q200 will cut off.

primary winding (phase A) of transformer T1,

transistor Q201 will provide 37 vdc through

through transistor Q200 to ground. This condition

primary winding (phase A) of transformer T1 (op-

will last for 120 degrees of a 360 degree cycle.

osite direction from previous current flow). By

During this 120 degree period the waveshape at

continuing the above process a quasi waveshape will

point went positive causing transistor Q402 to

be produced for each of the three phases as shown in

conduct through transformer. T401 in such a

figure 2-5.

direction that the polarity dots will be positive. This

positive will forward bias transistor Q203. At the

2-8