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REV.-A
(6) The above causes the energy previously induced in the secondary side (in step (4), above) to be
released from coils 0-@, @-QJ), and
@-®
in the direction opposite to
@, and current flows in the
easy-flow direction of the diodes.
The secondary side therefore outputs a voltage
(7) The release of energy declines linearly over time. When energy release is completed, all T 1 coil
voltages momentarily reach zero. R3, however, again induces switching current
@ in the direction
of
@, and
Q 1 conducts. Because the potential at point
®
then surpasses that at point
@, the energy
in
e
10 is released, so that
@ is maintained.
(8) The sequence returns to the stage described in (3) above.
This repetition enables the circuit to maintain oscillation. R7 is involved, however, only at the time
of starting.
The above sequence is generally known as a self-excitation type ringing choke converter
(R.e.e.)
configuration.
Note that, at the instant when Q 1 goes off (in step (5), above), the potential at point
®
jumps violently
upwards, but because of the action of D2, the energy is fed into R5 and consumed.
Below are shown the waveforms for each part of the circuit.
As Figure 2-10 makes clear, the output voltage is controlled by the time period that Q 1 is off. In other
words, the circuit is controlled by controlling the period during which Q 1 is off.
Figure 2-9. Starting Circuit (Main Switching Circuit)
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