Global Specialties 1310 - Manual (Page 13)

3.12 SPLIT SUPPLY :
A split supply may be arranged by connecting the positive ( + )
terminal of one supply to the negative ( - ) terminal of any other
supply ( see figure 5 ). These connected terminals are then used
as circuit ground ( also called circuit common ). This arrangement
is often used with op-amps which required a +V and -V supply.
Figure 5 : Split Supply "Connection
CAUTION : The power supplies should not be connected in any
manner which causes electron current to flow out of a
positive ( + ) terminal or into a negative ( - ) terminal. This
would be a series subtraction configuration, and could
damage the 1310.
3.13 PARALLEL CONNECTION :
The variable supplies may be connected in parallel to increase
the available load current, giving an output of 1.3 to 20 volts at up
to 500 milliamps. However, current-equalizing resistors must be
used ( see figure 6 )
Figure 6 : Parallel Connection
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DIGITAL DISPLAY :
Display of voltage and current is accomplished by U
5' an ICL7107 3½
digit A / D converter LED display driver. Power for this device is supplied
by a separate transformer, T
1
. The center-tapped output of this
transformer is full-wave rectified by diodes D
1 through D 4 and filtered
by capacitors C
1 through C 4
. The +5V supply, used only by U
5' is
created by U
1' a 7805 three-terminal 5 volt regulator, whose output is
further filtered by capacitors C
5 and C 7
. The -5A supply, also used only
by U
5' is produced by zener diode D 5' with filter capacitors C 6 and C 7
.
The A / D converter is calibrated for a full scale range of 200mV. The
current and voltage outputs of the variable supplies are therefore scaled
to accommodate this range, and the signals are routed to the A / D
converter through switches S
2 ( the A / B supply switch ) and S 3 (the V
/ A select switch). The yields a display of 000 - 250 to represent a
current flow from the variable supplies of 0 to 250 milliamps, and a
display of 013 - 200 to represent an output voltage of 1.3 to 20.0 volts.
When in the voltage range, the proper decimal point on the LED display
is illuminated by the action of switch S
3 to correctly indicate the voltage.
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