
25 2
Analog Electronics
Choke
To post-regulator
Figure
10.8 Choke input phase-controlled preregulator. Note that only two of the bridge rectifier diodes need to be
replaced by SCRs.
even down to zero, it is advisable to take some
precautions to avoid the large rise in output
voltage below the critical current. One simple step
is to fit a bleed resistor or 'bleeder' to draw a
current equal to the critical current. The resultant
waste of power can be minimized by using a choke
with a very large inductance, to make the required
magnetizing current, and hence the critical cur-
rent, very small. However, a larger inductance will
be more expensive ...