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Circuit Description-Type 324
When the Power Pack is being charged and the oscillo
scope POWER switch is turned on, the base of Q 634 Is
driven negative between charging current pulses. This
occurs because the battery reverses current flow through
R615 while it supplies the oscilloscope with power. The net
result is that the average charge on C636 tends to decrease,
♦
providing more drive to Q 634. This permits more current to
flow through Q617, keeping the average charge o n C 6 3 6 e t
its previous value by supplying the battery with additional
current to make up for that being drained between half
cycles. See Fig. 3-5(B).
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