PASCO PI-9880 Power Supply User Manual
Page 8
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D C P r o g r a m m a b l e P o w e r S u p p l y
01 2 - 1 2 69 5 A
S p e c i f i c a t i o n s
8
Experiment-design Considerations
Please note the following properties of
the Programmable Power Supply when planning an application:
•
The Power Supply is over-current protected, but it is not current-limited or
current-regulated. If the maximum output current (1 amp by default, or lower if
you have changed the maximum-current setting) is exceeded, the Power Supply
will need to be manually reset before operation can resume. See “Over-current”
on page 20.
•
The output voltage range is 0 to 18 V. To achieve a negative voltage switch the
positive and negative leads.
•
This device is a programmable power source, not a function generator. The max-
imum frequency of the rectangle and ramp functions is 10 Hz. The maximum fre-
quency of the default sine-wave custom program is about 0.1 Hz.
•
The Power Supply is designed for current flow in one direction: out of the posi-
tive terminal and into the negative terminal. In the example illustrated below, the
Power Supply is switched from 0 V to 5 V, then back to 0V. The capacitor does
not discharge in a predictable way because there is not a simple path to ground.
To provide a path to ground, connect a resistor across the Power Supply’s
terminals as shown.
A current-sinking resistor is not typically required when driving motors, lamps
and heating resistors since these devices have a low DC resistance.
Power
Supply
+
-
100 mF
100 W
100 mF
100 W
Power
Supply
+
-
20 W