APPENDIX L POWER SUPPLIES 2. WP-775B Single-Output DC ...

APPENDIX L POWER SUPPLIES
2. WP-775B Single-Output DC Power Supply
Purpose:
The WP-775B Single-Output DC Power Supply, hereafter denoted “power supply”
provides both adjustable output voltage and direct current.
Controls:
1. POWER ON: This is the main power switch.
2. Voltage meter: This meter indicates the output voltage as measured at the
output terminals.
3. Current meter: This meter indicates the output current as measured at the
output terminals.
4. COURSE VOLTAGE adjust: Allows you to set the voltage to the closest
tenth of a volt.
5. FINE VOLTAGE adjust: Allows you to set the voltage to a thousandth of a
volt.
6. CURRENT adjust: Allows one to adjust the upper (“compliance”) limit of the
output current between minimum (MIN) and maximum (MAX) values.
7. OUTPUT terminals. There are three terminals, representing positive,
negative and ground.
8. Mechanical meter zero. This is a screw adjustment for setting the zero point
of the analogue panel meters.

9. HI/LO switch. This switch selects the top (HI) or bottom (LO) scale of the
current output and corresponding meter scale. You should not adjust this without
consulting your instructor, since HI range currents may damage equipment.
10. CC lamp: When the power supply is in an overload or short condition, the
light will be ON. It means that the output DC voltage will be down until output
current adjust is cut to a lower value.
11. CV lamp: When the power supply is in a normal working mode, the lamp
will be ON. But when the power supply is in an overload or short condition, the
light will be OFF.
Preset Procedures:
1. Before applying power, make sure that the AC input voltage is correctly set on
the back of the power supply for your available power.
2. Connect the power supply to an AC power source using the line cord provided
and turn the POWER ON switch on. For maximum stability, allow the
instrument to warm up for at least 20 minutes.
3. Set the voltage and current adjustment knobs as you desire.
Operating Notes:
1. Verify that the AC voltage setting is the same as your available power before
you apply power to the power supply.
2. Do not connect a voltage that is greater than the current output voltage to the
terminals of the instrument.
3. Do not connect the output of two or more power supplies in parallel.
4. When the power supply is not to be used in a portion of the procedure, turn the
output voltage to minimum.
3. Tektronix PS281 DC Power Supply
Purpose:
The PS281 DC Power Supply, hereafter denoted “power supply” provides both adjustable
output voltage and direct current at up to 90 W of power (up to 30 V, 3 A), with a 3 and one-half
digit digital readout.
Front Panel Controls:
1. POWER switch: Turns on the AC line power to the instrument.
2. Digital readout: A four-digit display that shows the output of the power supply
in either volts or amperes.
3. VOLTS/AMPS selector: A switch that controls which unit (amps or volts) is
displayed on the readout; an LED will light next to the unit presently displayed.
This switch only affects the display; it does not affect the output of the supply in

any way.
4. VOLTAGE controls: The FINE and COURSE voltage knobs can be turned to
set the output voltage when in the constant voltage mode. The constant voltage
(C.V.) indicator lights when the power supply is in the constant voltage mode
(when the voltage limit is set lower than the current limit for a given load).
5. CURRENT controls: The FINE and COURSE current knobs can be turned to
set the output current when in the constant current mode. The constant current
(C.C.) indicator lights when the power supply is in the constant current mode
(when the current limit is set lower than the voltage limit for a given load). The
HI/LO AMPS button selects either a high or low (greater or less than 2A,
respectively) range of current.
6. Output jacks: Banana jacks that carry the power supply output to a load. The
plus (red) and minus (black) carry current, and the ground (green) jack is
connected to the chasis and earth ground through the AC power cord.
Rear Panel Controls:
1. Power cord jack: A standard, three-prong power connector to receive AC line
power.
2. Safety fuse holder: A safety fuse is located beneath the power cord jack to
protect the instrument against drawing excessive current. A spare fuse is also
located in the holder.
3. LINE VOLTAGE SELECT: Consists of a top switch and bottom switch that
are set in tandem to configure the power supply for the available AC power (100,
120, 220 or 240 V). See the label on the back of the power supply for the
appropriate switch positions for each AC voltage type. Consult your instructor if
you are unsure of the proper setting of these switches.
4. REMOTE section: The switches and terminals in this section are used to set
the power supply up in a parallel or series connection with other supplies, use the
supply in the MASTER or SLAVE modes, or control the power supply output via
an externally applied (remote) voltage source. These controls will not be used in
laboratory exercises. Consult your instructor or the power supply manual if
questions arise concerning these controls.
Preset Procedures:
1. Before applying power, make sure that the AC input voltage is correctly set on
the back of the power supply for your available power.
2. Connect the power supply to an AC power source using the line cord provided
and turn the POWER ON switch on. For maximum stability, allow the
instrument to warm up for at least 20 minutes.
3. Initially set the voltage and current adjustment knobs to full counterclockwise
(effectively no output) position; then you may adjust them as you desire.
Operating Notes:

1. Verify that the AC voltage setting is the same as your available power before
you apply power to the power supply.
2. Do not connect a voltage that is greater than the current output voltage to the
terminals of the instrument.
3. Do not connect the output of two or more power supplies in parallel.
4. When the power supply is not to be used in a portion of the procedure, turn the
output voltage to minimum.
5. A more precise multimeter may be necessary to accurately read output levels at
low output settings, due to the limited precision of the 3.5 digit display (e.g., only
one digit may be active).