Simpson 460 4 Series - Page 46

Theory of Operation
into 7-Segment information, and numerically displayed through
the Segment and Anode Drivers.
5.4.6 The other requirements of the A/D Converter such as
overrange and polarity indications are accomplished by the Con-
trol Logic and Counter Circuits.
5.5 POWER SUPPLY CIRCUITS
5.5.1 AC Line Power
5.5.2 The AC line power supply is shown in Figure 7-2, Sche-
matic Diagram. The incoming AC power is applied to the primary
power transformer T,. The primary winding is tapped for 240
VAC, 220 VAC and 120 VAC operation. The secondary wind-
ings generate step-down voltage to provide 3 regulated DC
voltages.
5.5.3 Regulated DC voltages of +12V and —12V are produced
by two full-wave rectifiers, followed by two series-type voltage
regulators. These regulated voltages are used to supply power
to the analog circuits.
5.5.4 А full-wave rectifier, followed by IC12, provides a regu-
lated +5V supply to all digital integrated circuits and the LED
display. An unregulated +15V is generated for operating the
Resistance Converter.
5.5.5 Battery Power (460D only)
5.5.6 The battery-operated power supply of the 460D is shown
on Figure 7-2, Schematic Diagram. With the POWER switch ON,
the battery is connected to the input of the DC-To-Dc converter
consisting essentially of T201 and transistors Q201 and Q202
in a multivibrator configuration. The multivibrator signal is
coupled by T201 to bridge rectifier and regulators to generate
5-10