TM 11-6130-243-35
configuration as shown in the simplified sche-
matic diagram (A, fig. 1-4). Each secondary
winding applies an ac voltage to a bridge rec-
tifier circuit consisting of four of the six
diodes CR1 through CR6. The middle sec-
ondary winding of transformer T1 (fig. 4-3) is
associated with the bridge rectifier consisting
of diodes CR2, CR3, CR5, and CR6 as shown
in the simplified schematic diagram (B, fig.
transformer T1 is associated with diodes CR1,
CR2, CR4, and CR5 while the bottom wind-
ing is associated with diodes CR1, CR3, CR4,
and CR6. The simplified schematic diagram
with the middle winding.
b. When the half-cycle of the ac voltage oc-
curs, making secondary winding terminal 9
positive with respect to terminal 10 (B, fig.
biased and diodes CR2 and CR6 become re-
verse-biased. Electrons flow from terminal 10
through diode CR3, resistors R1 and R2 diode
CR5, terminal 9, and to terminal 10. The cur-
schematic diagram.
rent pulse thus produced causes a dc voltage
of the polarity indicated on figure 1-4 to ap-
pear across resistors R1 and R2. During the
other half-cycle, diodes CR2 and CR6 become
DIRECT CURRENT VOLTS meter M2 is
connected across the output of the power sup-
forward-biased and diodes CR3 and CR5 be-
ply and monitors the output voltage. DIRECT
come reverse-biased. Electrons flow from ter-
CURRENT AMPERES meter M1 monitors
minal 9 through diode CR2, resistors R1 and
output current whenever spring-loaded AM-
R2, diode CR6, terminal 10, and to terminal 9.
This current pulse also causes a dc voltage
METER switch S1 is set to the READ (de-
of the same polarity to appear across resistors
pressed) position. With switch S1 de-
R1 and R2.
pressed, load current flowing through low-re-
sistance shunt resistor R3 produces a small
c. The dc voltage pulses appearing across
voltage drop which is proportional to the cur-
resistors R1 and R2 are applied to the choke-
rent. Although the scale of DIRECT CUR-
input filter consisting of inductor L1 and ca-
RENT AMPERES meter M1 is marked to in-
pacitors C1 and C2. The filter network
dicate amperes, the meter is actually a milli-
smoothes the ripple and assists in power sup-
voltmeter which measures the voltage across
ply regulation. AS a result, the output volt-
shunt R3. Resistor R4 is a calibrating resistor
age approaches the average value of voltage
for meter M1. When AMMETER switch S1 is
produced by the bridge rectifiers. Bleeder re-
released to the OFF position, the switch
sistors R1 and R2 also provide a discharge
creates a short circuit across R3, R4, and M1.
path for capacitors C1 and C2.
