GW Instek GPD-4303S - Manual (Page 15)

OVERVIEW
Auxiliary Rectifier The auxiliary rectifiers D1011~ D1014 provide bias
voltage filtered by the capacitors C102 and C103,
for the pre-regulators U101 and U102. They
provide a regulated voltage for other modules.
Main Rectifier The main rectifier is a full wave bridge rectifier. It
provides the power after the rectifier is filtered by
the capacitor C101, and then regulated via a series-
wound regulator, which is finally delivered to the
output terminal.
Current Limiter U104 acts as a current limiter. When the current is
over predetermined rating, U104 is activated and
decreases the current. U208 provides a reference
voltage. U206 is an inverter amplifier. U103 is a
comparator amplifier which compares the
reference voltage to the feedback voltage, and then
delivers it to Q102, which then calibrates the
output voltage.
Overload When the unit is overloaded, Q107 activates to
control the current magnitude of Q102, to limit the
output current. The relay control circuit controls
the power dissipation in the series-wound
regulated circuit.
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