TM 11-6625-539-14-4
FUNCTIONING OF EQUIPMENT
5-1. Basic Functioning of
Test Set
the device under test through a drive amplifier,
a. The basic functioning of the test set is shown
either in conjunction with closed feedback loops or
calibrated signals to provide either an ac or dc
test set is provided by six dry cells in the battery
signal as required.
supply. The battery supply energizes the multivi-
brator section which provides a 1-kHz square
b. The collector sense amplifier is used in beta
wave output that generates signals to drive the
measurements, and forces the transistor under
device under test and also the regulating voltage-
test to conduct an average of 1-mA collector cur-
rent. The meter sense amplifier converts the cur-
rent from the device under test to a proportional
voltage. The meter amplifier drives the meter. A
three-decade divider produces three ranges for
each parameter.
5-2. Regulated Power Supply
a. A simplified schematic diagram of the regu-
circuit converts the 9-volt battery supply to a
regulated +5.1 and -5.1 output.
b. Transistors Q3 and Q5 are driven out of phase
tion with analog switch Z1C and Z1D. When Q3 is
turned on, the 9-volt battery power supply is
applied direct to C13 through Q3 and CR15. At the
same time, transistor Q6 base emitter and Zener
diode CR16 provide a clamp for the base of Q3,
forcing Q3 to cut off when voltage across capacitor
C13 is equal to the voltage of Zener diode CR16
and base emitter voltage of Q6, minus the base
emitter voltage of Q3. Transistors Q6 and Q3 are
in thermal contact to provide temperature com-
pensation for the base-emitter voltage of Q3. This
way, the voltage across C13 (5.1-volt supply) is
equal to the zener voltage of CR16, and will
continue to be regulated as long as the battery
power supply is sufficient to cause the zenering.
c. The two halves of the power alternate charg-
ing their respective capacitors C12 and C13 to
EL6625-539-14-4-TM-4
produce two supplies of opposing polarity. These
supplies power the remaining circuits of the test
set.