PASCO PI-9877, Instruction Manual

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DC Power Supply Basic Operation
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Safety Feature: Whenever the Power Supply enters Constant DC mode, the output voltage is
automatically set to zero.
Set Voltage
Rotate Coarse knob to change the output voltage by 1.0 V per detent;
rotate the Fine knob slowly to change the voltage by 0.01 V per detent, or quickly to
change the voltage by 0.04 V per detent.
By default the output voltage is limited to 18 V, but this limit may be set lower. If a
load is connected to the Power Supply, the highest allowable voltage may also be lim-
ited by the maximum-current setting, which is 1 A by default. See “Maximum Val-
ues” below for instructions on setting these maximums.
Voltage and Current Display
To switch the display from voltage to current,
press (DISPLAY); the output current appears on the display, and the Current LED
lights. Press (DISPLAY) again to switch the display back to voltage.
When current is displayed, rotating the Coarse and Fine knobs adjusts the voltage .
Note that the current is not regulated. If the load changes the voltage will remain con-
stant at its set value, but the current will change.
In Constant DC mode you can set the display to cycle between voltage and current.
Press
and hold (SET) while rotating the Coarse knob to set the cycle time in sec-
onds (while you are making this adjustment, the Time LED is lit and the display
shows the cycle time); then release the button. The display alternates between current
and voltage at a rate determined by the cycle time that you set. Press
(DISPLAY)
to pause the display on voltage or current; press again to restart alternating. To
disable alternating display mode, press and hold (SET) while rotating the knobs to
set the cycle time to zero.
You can also press and hold (STOP) to reset both the cycle time and the voltage to zero.
Output Switch-off
To temporarily switch off the output, press . The Voltage
LED blinks quickly to indicate that the actual output voltage is zero even though the
voltage
setting (which may not be zero) is displayed. While the output is switched off,
you can turn the Coarse and Fine knobs to adjust the voltage setting. Press again
to switch the output voltage back on.
Over-current
If output current exceeds the maximum-current setting (see “Maxi-
mum Values” below), the output voltage drops to zero, the display reads OL (for
“overload”), and Current LED flashes amber. Press (START) to resume normal
operation.
Reset Output and Display
Press and hold (STOP) to set the voltage to zero
and set the display to show voltage. The output and display are also reset in this way
if you turn the Function knob and return it to Constant DC mode.
Maximum Values
By default, the Power Supply is set for a voltage limit of 18 V and a maximum current
of 1 A. The Power Supply will not allow its output to exceed the voltage limit, and it
will turn off the output if it exceeds the maximum current. To lower the
maximum-allowable voltage or current, turn the Function knob to SET MAX. In this
mode you can also set the Power Supply to turn off the output after a specified time.
In SET MAX mode, the display shows maximum-value settings; the actual output
voltage is always zero.
To prevent accidental damage to lab equipment, set an appropriate maximum voltage or current
for the equipment that the Power Supply will be used with.
Display reads OL if the
maximum current is
exceeded