INSTRUCTION
MANUAL
Manual de Instruccíon
MODELS: 1760A & 1761
Para los modelos 1760A y 1761
Triple Output
DC POWER SUPPLY
With Dual 4- Digit LED Displays
Fuentes de Poder de Triple Salida
DC
Con Pantalla tipo LE D Dual de 4
Dígitos
TEST INSTRUMENT SAFETY
Normal use of test equipment exposes you to a certain amount of danger from electrical shock because testing must sometimes be
performed where exposed high voltage is present. An electrical shock causing 10 milliamps of current to pass through the heart will
stop most human heartbeats. Voltage as low as 35 volts dc or ac rms should be considered dangerous and hazardous since it can
produce a lethal current under certain conditions. Higher voltages are even more dangerous. Your normal work habits should
include all accepted practices to prevent contact with exposed high voltage, and to steer current away from your heart in case of
accidental contact with a high voltage. Observe the following safety precautions:
1. There is little danger of electrical shock from the dc output of this power supply. However, there are several other possible test
conditions using this power supply that can create a high voltage shock hazard:
a. If the equipment under test is the “hot chassis” type, a serious shock hazard exists unless the equipment is unplugged (just
turning off the equipment does not remove the hazard), or an isolation transformer is used.
b. If the equipment under test is “powered up” (and that equipment uses high voltage in any of its circuits), the power supply
outputs may be floated to the potential at the point of connection. Remember that high voltage may appear at unexpected
points in defective equipment. Do not float the power supply output to more than 100 volts peak with respect to chassis or
earth ground.
c. If the equipment under test is “off” (and that equipment uses high voltage in any of its circuits under normal operation),
discharge high-voltage capacitors before making connections or tests. Some circuits retain high voltage long after the
equipment is turned off.
2. Use only a polarized 3-wire ac outlet. This assures that the power supply chassis, case, and ground terminal are connected to a
good earth ground and reduces danger from electrical shock.
3. Don’t expose high voltage needlessly. Remove housings and covers only when necessary. Turn off equipment while making
test connections in high-voltage circuits. Discharge high-voltage capacitors after removing power.
(continued on inside back cover)
WARNING
2
Instruction Manual
For Models
1760A and 1761
Triple Output DC Power Supplies
With Dual 4-Digit LED Displays
22820 Savi Ranch Parkway
Yorba Linda, CA 92887
www.bkprecision.com
3
TABLE OF CONTENTS
Page
Page
TEST INSTRUMENT SAFETY---------------inside front cover
INTRODUCTION----------------------------------------------------5
FEATURES ------------------------------------------------------------ 7
SPECIFICATIONS --------------------------------------------------- 8
CONTROLS AND INDICATORS-------------------------------10
General Controls and Indicators ----------------------------------10
4-6.5 V Supply Controls and Indicators -------------------------10
“A” Supply Controls and Indicators -----------------------------12
“B” Supply Controls and Indicators------------------------------12
Rear Panel Controls -------------------------------------------------13
OPERATING INSTRUCTIONS----------------------------------14
Safety Precautions---------------------------------------------------14
Equipment Precautions ---------------------------------------------14
Independent Use of “A” Or “B” Supply-------------------------14
Hook-up ---------------------------------------------------------------15
Typical Constant Voltage Operation-----------------------------18
Setting Current Limit -----------------------------------------------19
Typical Constant Current Operation -----------------------------20
Constant Voltage/Current Characteristic------------------------21
Series Tracking Operation -----------------------------------------22
Parallel Tracking Operation ---------------------------------------26
4-6.5 V Power Supply Operation ---------------------------------29
APPLICATION ---------------------------------------------------------33
General--------------------------------------------------------------------33
Electronics Servicing --------------------------------------------------33
Electronics Manufacturing--------------------------------------------33
Electronics Design Lab ------------------------------------------------34
Electronics Education--------------------------------------------------34
Battery Charging--------------------------------------------------------34
Split Supply --------------------------------------------------------------34
MAINTENANCE-------------------------------------------------------41
Fuse Replacement ------------------------------------------------------41
Line Voltage Conversion----------------------------------------------41
Adjustments --------------------------------------------------------------42
“A” Supply and “A” Metering Adjustments-----------------------42
4-6.5 V Supply and 4 -6.5 V Metering Adjustments -------------44
“B” Supply and Metering Adjustments-----------------------------44
“B” Series Tracking Adjustment -------------------------------------45
Instrument Repair Service --------------------------------------------45
WARRANTY SERVICE INSTRUCTIONS-----------------------46
LIMITED TWO-YEAR WARRANTY-----------------------------47
SPANISH MANUAL --------------------------------------------------49
4
INTRODUCTION
These B+K Precision Triple Output DC Power Supplies are high
In constant current applications, the maximum voltage may
quality, general purpose dc power sources. They provide two “main”
supplies with a 0-30V (0-35V model 1761) volt dc output and a “third”
output with a 4-6.5A (2-6.5A model 1761) volt dc output. The “main”
V supplies are adjustable with both coarse and fine voltage controls for
precise settability and are capable of current output of 0-2 (0-3 model
1761) amps. The “third” supply has a current output of 0-5 amps,
allowing it to handle extensive digital logic circuitry. Two large panel-mounted LED meter displays can monitor either the output current or
output voltage of each supply.
The two “main” volt supplies can be operated independently or in
one of two tracking modes. In the series tracking mode, the “B” Supply
tracks from 5% to 100% of the voltage of the “A” Supply. Maximum
current setting of the two supplies can still be set independently when
in the series tracking operating mode. In the series tracking mode the
“A” and “B” supplies are connected in series, allowing a single output
of 0-60 (0-70 model 1761) V at up to 2 (3 model 1761) amps. In the
parallel tracking mode, the two supplies are connected together in
parallel, allowing a single 0-30 (0-35 model 1761) V output at up to 4
(6 model 1761) amps.
Both “main” volt supplies may be used in constant voltage or
constant current applications. The crossover from constant voltage to
constant current modes is smooth and automatic. LED’s indicate the
“CV” (constant voltage) or “CC” (constant current) mode of operation.
In constant voltage applications, a current limit may be preset. When
load variations cause the current to reach the preset limit, the unit then
regulates output current rather than output voltage. Current limits are
adjustable from 5% to 100% of maximum.
be preset. When load variations cause current to drop below
the regulated value, the unit reverts to regulated voltage
operation at the preset value.
The “third” V supply is ideal for powering digital logic
circuitry. The 0-5 amp capacity allows the supply to be used
for large circuits. Built-in overload protection automatically
limits the current output to a maximum of 5 amps. An
indicator lights when the supply is overloaded.
These models exhibit excellent regulation and low ripple
characteristics. The circuit design incorporates a pre-regulator,
which greatly reduces internal power dissipation at low output
voltages.
Reverse polarity protection prevents accidental damage to
the power supply from improper connection to an external
voltage, and current limiting protects the equipment being
powered, as well as the power supply.
The output is isolated from chassis and earth ground, which
permits full flexibility of connections. When needed, the (+)
or (-) polarity may be strapped to ground, or either polarity
may be floated to an external voltage. Additionally, the two
“main” volt sup plies can be used as a “split supply” with two
positive voltages and a common negative, two negative
voltages and a common positive, or one positive, one
negative, and a common. All of these configurations can be
used with either matching (tracking) or differing
(independent) voltages.
5
The features and versatility of the unit, especially the triple output
The same features that make the Model 1760 a good
and tracking features, make it an ideal general purpose power
supply for engineering lab applications. It can serve as a single or
multi-voltage power source, including the bias supply, for
breadboard and prototype circuits and equipment. It can provide
single or simultaneously varying voltages for circuit evaluation. It
can provide tracking (+) and (-) voltages for evaluating differential
amplifiers. It may be used as a battery eliminator, or to power
individual circuit boards or cards while removed from the system.
Its output can be evaluated while powering a breadboard or
prototype circuit to determine the circuit’s power supply
requirements. Its laboratory quality specifications will meet most
engineering laboratory requirements.
choice for an engineering lab also make it a good choice for
most other solid state electronic applications. These
applications include service shops; industrial production
testing of components, assemblies, and complete equipment;
for school laboratories, and home use by electronic
hobbyists.
6
FEATURES
TRIPLE OUTPUT
CONSTANT VOLTAGE OR CONSTANT CURRENT
reverse po
larity.
Operates as three separate power supplies. Each has floating
output and is completely isolated from the other two.
ONE 4 TO 6.5 V (2 to 6.5V model 1761) SUPPLY
Durable 0-to-5 amp supply is ideal for use with most digital
logic circuitry. Adequate current capacity for extensive circuitry.
TWO 0-30 VOLT (0-35V model 1761) SUPPLIES
“A” and “B” supply are continuously variable over their
respective voltage ranges with coarse and fine controls. Each
supply has a 2 amp (3 amp model 1761) current capacity.
UNIQUE TRACKING FEATURE
The two 0-to-30V (35V model 1761) supplies can be operated so
that the “B” supply tracks the “A” supply. Outputs can be strapped
for two positive voltages with a common negative, two negative
voltages with a common positive, or one positive and one negative
with a neutral common.
SINGLE 0-60V (0-70V mo del 1761) SUPPLY
Series tracking feature allows use of “A” and “B” supplies as
one 0-to-60V, 2 amp (0-70V, 3 amp model 1761) supply.
SINGLE 0-30V, 4A (0-35V, 5A model 1761) SUPPLY
Parallel tracking feature allows use of “A” and “B” supply as a
0-to-30 (0-35V model 1761) V supply with a 4 amp (6 amp model
1761) current capacity (through “A” output terminals).
The “A” and “B” supplies provide regulated dc voltage
output or regulated dc current output. Crossover is smooth and
automatic.
LED DISPLAY
Two large, easy-to-read LED 4-digit displays monitor
output voltage or output current of all three supplies. Use of
two meters allows simultaneous current and voltage metering
when using “A” and “B” supplies in tracking operat ion. Good
visibility in bright or low light.
LABORATORY QUALITY
Excellent regulation, low ripple.
PRE-REGULATOR
Limits internal dissipation for higher reliability and
efficiency.
ISOLATED OUTPUT
Either polarity may be floated or grounded.
OVERLOAD PROTECTION
Fully adjustable current limiting (from 5% to 100% of
maximum output current) for “A” and “B” supplies protects
circuit under test and the power supply.
REVERSE POLARITY PROTECTION
Prevents damage to power supply from external voltage of
7
“A”
AND “B” SUPPLIES
Tracking Series, “B” tracks “A”:
Output Voltage Range:
0V to 30V (0V to 35V model 1761)
Output Current Limit Range:
0.1A (5%) to 2A (3A model 1761) (100%).
Load Regulation (Constant Voltage):
=0.01% + 3 mV.
Line Regulation 108 - 132 V (Constant Voltage):
=0.01% + 3 mV.
Ripple (Constant Voltage):
=1 mV RMS.
Recovery Time (Constant Voltage):
=100 ~S.
Temp. Coefficient (Constant Voltage):
<300 ppm/°C.
Load Regulation (Constant Current):
=0.2% + 3mA.
Line Regulation 108 - 132 V (Constant Current):
=0.2% + 3mA.
Ripple Current (at 108 V for Constant Current):
=3mA RMS.
Tracking (Series) Accuracy:
±0.2% + 10mV.
SPECIFICATIONS
5% to 100%.
Panel Meter Accuracy (Volts):
±0.5% + 9 digits.*
Panel Meter Accuracy (Current):
±0.5% + 9 digits.*
(* see note 1)
“Third” SUPPLY
Output Voltage Range:
4V to 6.5V (2V to 6.5V model 1761)
Load Regulation (Constant Voltage):
=10mV (0 to 5A load).
Line Regulation 108 - 132V (Constant Voltage):
=l 0mV.
Ripple and Noise:
=2mV RMS.
Over Voltage Protection Threshold:
6.8V to 7.3V.
Panel Meter Accuracy:
Same as “A” Supply Meter.
8
SPECIFICATIONS
GENERAL
Dimensions (H x W x D):
Power Requirements:
Domestic: 120 VAC + 10%, 60 Hz.
International: 120/220/230/240 VAC -* 10%, 50/60 Hz.
Power Consumption (Fully Loaded):
Approximately 350 W.
Protection:
Reverse polarity protection and current limiting.
NOTE: Specifications and information are subject to change without notice. Please visit www.bkprecision.com for the most current product
information.
Note 1:
Important: Even with noticeable Thermal Drift, this high resolution power supply will be considerably more accurate than any standard three
digit display bench power supply.
Thermal Drift: Since this power supply has greater resolution than standard bench power supplies they are more susceptible to Thermal
Drift. Thermal Drift occurs on almost every type of power supply but is more apparent on high resolution types. Thermal Drift results in the
metering of the power supply to either slowly increase or decrease with the change in the power supply’s internal temperature. As the power
supply outputs more power its internal temperature will increase causing the metering (primarily the current) to slowly increase. As the power
demand is deceased the power supply will cool causing the metering (primarily the current) to slowly decrease. If the power supply remains
with a constant output of power for more than fifteen minutes the power supply metering will remain constant and should not continue to
drift.
5.7" x 10.5" x 15" (145 mm x 267 mm x 381 mm).
Weight:
10 kg (21 lbs).
Accessories Supplied:
Two earth ground bus straps.
9
CONTROLS AND INDICATORS
10
GENERAL CONTROLS AND INDICATORS
1. POWER Switch. Turns power on and off.
2. TRACKING Mode Switches. Two pushbutton switches that select
INDEPendent mode, SERies tracking mode, or PARallel tracking
mode as follows:
a. When INDEP/TRACK switch is disengaged (out), the unit is in
the INDEPendent mode and the “A” and “B” power supplies are
completely independent from one another.
b. When the INDEP/TRACK switch is engaged (in) and the
SER/PAR switch is disengaged (out), the unit is in the TRACKing SERies mode. In this mode, maximum voltage of both
supplies is set using the “A” VOLTAGE controls (voltage at
output terminals of the “B” supply tracks the voltage at the
output terminals of the “A” supply). Also, in this mode of
operation the positive terminal (red) of the “B” supply is
internally connected to the negative terminal (black) of the “A”
supply. This allows the two supplies to be used as one 0-to-60
volt supply.
c. When both INDEP/TRACK and SER/PAR switches are engaged
(in), the unit is in the TRACKing PARallel mode. In this mode
the “A” and “B” supplies are wired together in parallel and both
the maximum current and voltage are set using the “A” controls.
The “A” and “B” outputs can be used as two individual (but
tracking) power supplies or just the “A” output can be used as a
0-to-30 volt supply with a 4 A capability.
3. 0-30V/4-6.5V Switch. Controls “A”/4-6.5V LED Display.
When this switch is in the 0-30V position (out), the LED
display monitors the “A” (0-30 V) supply. When this switch is
in the 4-6.5V position (in), the LED display monitors the 4-
6.5V supply.
4. Right V/A Switch. Selects current or voltage metering mode
for the “A” 0-30 V supply or the 4-6.5 V supply (depending on
setting of 0-30 V/4-6.5 V switch). When in the A (amps)
position (in), current is read from the “A”/4-6.5 V LED
Display. When in the V (volts) position (out), voltage is read
from the “A”/ 4-6.5 V LED Display.
5. “A”/4-6.5 V LED Display . Digital display indicates voltage or
current at the 0-30 V “A” supply or the 4-6.5 V supply
(depending on the setting of the Right V/A and 0-30 V/4 -6.5 V
switches).
4-6.5 V SUPPLY CONTROLS AND INDICATORS
6. “-” Terminal (Black). Negative polarity output terminal for 4-
6.5V supply.
7. “+” Terminal (Red). Positive polarity output terminal for 4-
6.5V supply.
8. Voltage Level Control. Adjusts output voltage for 4-6.5V
supply. Fully counterclockwise rotat ion adjusts output voltage
to 4V. Clockwise rotation increases voltage to a maximum of
6.5V (full clockwise rotation).
5 A OVERload Indicator. Lights when load on 4-6.5 Volt supply
becomes too large
CONTROLS AND INDICATORS
Fig. 1. Front Panel Contr
ols and Indicators.
11
“A” SUPPLY CONTROLS AND INDICATORS
9. C.C. (Constant Current) Indicator. Red LED lights when
“A” supply is in the Constant Current mode. The Power
Supply regulates the output current at the value set by the “A”
CURRENT control. In the Parallel Tracking mode, when this
indicator is lit, both the “A” and “B” supplies are in the
Constant Current mode.
10. C.V. (Constant Voltage) Indicator. Green LED lights when
the “A” supply is in the Constant Voltage mode. The Power
Supply regulates the output voltage at the value set by the “A”
VOLTAGE controls. In either the Series or Parallel Tracking
mode, when this indicator is lit, both the “A” and “B”
supplies are in the Constant Voltage mode.
11. Coarse VOLTAGE Control. Coarse adjustment of the output
voltage of the “A” supply. Also functions as coarse
adjustment control for the maximum output voltage of the “B”
supply when either parallel or series tracking mode is selected.
Read the value on the “A”/4-6.5 V LED Display when the
voltage (V) and master (0-30 V) metering modes are selected.
12. Fine VOLTAGE Control. Fine adjustment of output voltage
of the “A” supply. Also functions as fine adjustment control
for the maximum output voltage of the “B” supply when
either parallel or series tracking mode is selected. Read the
value on the “A”/4-6.5 V LED Display when the voltage (V)
and master (0-30 V) metering modes are selected.
13. CURRENT Control. Adjusts current limit of “A” supply in
constant voltage mode. Adjusts constant current value of “A”
supply in constant current mode. Current can be read from the
“A”/4-6.5V LED Display when the current (A) and master (0-
30V) metering modes are selected.
14. “+” Terminal (Red). Positive polarity output terminal for the
“A” supply. Also serves as the positive polarity terminal for 4
A parallel and 0-to-60 V series tracking operation.
15. Terminal (Green). Earth and Chassis Ground.
16. “-” Terminal (Black). Negative polarity output terminal for
the “A” supply. Also serves as the negative polarity terminal
for 4 A parallel tracking operation. In series tracking
operation, this terminal is internally tied to the (+) positive
terminal of the “B” supply.
“B” SUPPLY CONTROLS AND INDICATORS
17. C.V. (Constant Voltage) Indicator. Green LED lights when
the “B” supply is in the Constant Voltage mode. The Power
Supply regulates the output voltage at the value set by the “B”
VOLTAGE controls.
18. C.C. (Constant Current)/PARallel Indicator. Red LED
lights when “B” supply is in the Constant Current mode. The
Power Supply regulates the output current at the value set by
the “B” CURRENT control when in the series tracking or
INDEPendent modes. Also lights when the TRACKing
PARallel mode is se lected.
19. Coarse VOLTAGE Control. Coarse adjustment of the output
voltage of the “B” supply when the INDEP endent mode is
selected. Also sets the 5% to 100% tracking in the SERies
TRACKing mode. Disabled in the PARallel TRACKing mode.
Read the value on the “B” LED Display when the voltage (V)
metering mode is selected.
20. Fine VOLTAGE Control. Fine adjustment of output voltage of
the “B” supply when the INDEP endent mode is selected. Also
sets the 5% to 100% tracking in the SERies TRACKing mode.
Disabled in the PARallel TRACKing mode. Read the value on
12
21. the “B” LED Display when the voltage (V) metering mode is
selected.
22. CURRENT Control. Adjusts current limit of “B” supply in
constant voltage mode. Adjusts current value of “B” supply in
constant current mode. Current can be read from the “B” LED
Display when the current (A) metering mode is selected.
23. Left V/A Switch. Selects current or voltage metering mode for
the 0-30 V “B” supply. When in the A (amps) position (in),
current is read form the “B” LED Display. When in the V
(volts) position (out), voltage is read form the “B” LED
Display.
24. “B” LED Display. Digital display indicates voltage or current
at the 0-30 V “B” supply (depending on the setting of the A/V
switch).
25. “+” Terminal (Red). Positive polarity output terminal for the
“B” supply. In series tracking operation, this terminal is
connected to the negative terminal of the “A” supply.
26. Terminal (Green). Earth and Chassis Ground.
27. “-” Terminal (Black). Negative polarity output terminal for the
“B” supply. Also serves as the negative polarity terminal for 0to-60 V series tracking operation.
Fig. 2. Rear Panel Controls.
REAR PANEL CONTROLS
28. Fuse
29. Power Cord
30. 110/220 Line Voltage Conversion Switch
13
OPERATING INSTRUCTIONS
SAFETY PRECAUTIONS
EQUIPMENT PRECAUTIONS
Avoid contacting the heat sink at the rear of the
power supply. When the unit is providing large
amounts of current at any or all of its outputs, the
heat sink can become very hot. Contacting the
heat sink when it is hot could result in skin burns
or damage to the equipment in contact with them.
Use only a polarized 3-wire ac outlet. This assures that the power supply chassis, case, and
ground terminal are connected to a good earth
ground and reduces danger from electrical shock.
There may be great danger of electrical shock if
the power supply output is connected to an external high voltage. Some equipment being powered
may contain high voltage and present a shock
hazard. Observe caution. If the power supply
output is floated (referenced to a voltage rather
than earth ground) turn off the power supply and
the equipment under test when making connections. Never float the power supply to a potential
greater than 100 volts peak with respect to earth
ground.
CAUTION
Avoid using the power supply in ambient temperatures above
+40° C. Always allow sufficient air space around the heat sink at
the rear of the power supply for effective radiation to prevent
internal heat build-up.
Although the power supply is protected against reverse polarity
damage, the circuit being powered may not include such protection.
Always carefully observe polarity; incorrect polarity may damage
the equipment under test.
Do not exceed the voltage rating of the circuit being powered.
Many transistors and integrated circuits will not withstand voltage
of 30 volts.
There is no need to worry about voltage spikes or overshoot
damaging the equipment under test. The voltage between the output
terminals of the power supply never exceeds the preset value as the
POWER switch is turned on or off.
INDEPENDENT USE OF “A” OR “B” SUPPLY
The “A” and “B” supplies each provide a 0-to-30 volt output at
up to 2.0 amps. This procedure covers the use of the “A” and “B”
supplies only when they are used independently from one another.
When used in the INDEPendent operating mode, the operating
controls of the two power supplies are completely independent and
either supply can be used individually or both can be used
simultaneously. Basic operation is covered here. Several variations
are covered in the APPLICATIONS section of this manual.
14
Hook
-up
b.
Similarly, the positive polarity can be grounded by
1. Disengage the INDEP/TRACK mode switch so that the
power supply is in the INDEPendent operating mode.
2. Turn off the power supply and the equipment to be powered
during hook-up.
3. Connect the positive polarity of the device being powered to
the red (+) terminal of the power supply.
4. Connect the negative polarity of the device being powered to
the black (-) terminal of the power supply.
5. Fig. 3 illustrates the grounding possibilities when used in the
INDEPendent mode.
a. If the negative polarity of the equipment or circuit being
powered is also the chassis or common, it may be
grounded to earth by strapping the black (-) terminal to
the green ( ) terminal as shown in Fig. 3A.
OPERATING INSTRUCTIONS
strapping the red (+) terminal to the green ( )
terminal as shown in Fig. 3B.
c. If an earth ground reference is not required, the
configuration of Fig. 3C may be used. The scheme
in Fig. 3C should also be used where it is not
known whether the chassis is common with either
the positive or negative polarity.
d. If the chassis or common of the equipment being
powered is separate from both the positive and
negative polarity power inputs, use the connection
shown in Fig. 3D.
6. Observe proper polarity. If the circuit being powered
is not equipped with reverse polarity protection,
damage to the circuit can result from reverse polarity.
Use color coded hook-up leads, for convenience in
identifying polarity, red for (+) and black for (-).
7. Make sure that the hook-up leads offer sufficient
current capability and low resistance between the
power supply and the circuits being powered.
15
OPERATING INSTRUCTIONS
Fig. 3. Independent Operation Grounding Possibilities.
16
OPERATING INSTRUCTIONS
Fig. 3. Independent Operation Grounding Possibilities.
17
Typical Constant Voltage Operation
1. Before connecting the device to be powered to the power
supply, determine the maximum safe load current for the
device to be powered and set the current limit value (see
“Setting Current Limit” procedure in this section).
2. Set Fine VOLTAGE control to center and Coarse
VOLTAGE control to minimum (fully counterclockwise).
3. Turn off power supply and connect it to the device to be
powered (see “Hook -Up” procedure in this section).
4. Turn on POWER switch. The CV indicator should light.
5. Set the meter selection switch to the V posit ion to select the
voltage metering mode.
6. Increase the VOLTAGE setting until the LED display reads
the desired value. The Fine control permits easier setting to a
specific value.
7. Set the meter selection switch to the A position to select the
current metering mode and note the load current on the
display.
8. If the load current exceeds the preset current limit, the CV
indicator will go off and the CC indicator will light. In this
case, the power supply automatically switches to the constant
current mode and further rotation of the VOLTAGE control
will not increase the output voltage.
OPERATING INSTRUCTIONS
Fig. 4. Typical Constant Voltage Operation.
18
OPERATING INSTRUCTIONS
Setting Current Limit
1. Determine the maximum safe current for the device to be
powered.
2. Temporarily short the (+) and (-) terminals of the power
supply together with a test lead.
3. Rotate the Coarse VOLTAGE control away from zero
sufficiently for the CC indicator to light.
4. Set the meter selection switch to the A position to select the
current metering mode.
5. Adjust the CURRENT control for the desired current limit.
Read the current value on the LED display.
6. The current limit (overload protection) has now been preset.
Do not change the CURRENT control setting after this step.
7. Remove the short between the (+) and (-) terminals and hook
up for constant voltage operation.
Fig. 5. Setting Current Limit.
19
Typical Constan
t Current Operation
1. Before connecting the device to be powered to the power supply,
determine the maximum safe voltage to be applied, set the meter
selection switch to the V position, and set the VOLTAGE
controls to obtain that voltage reading on the LED display.
2. Determine the desired constant current value.
3. Set the CURRENT control to minimum (fully counterclockwise).
4. Turn off the power supply and connect it to the device to be
powered.
5. Turn on the power supply. The CC indicator should light if the
load is greater than 5% of full scale.
The CC indicator will not light if the load is less than 5% of
full scale or approximately 0.1A.
6. Set the meter selection switch to the A position to obtain the
current metering mode.
7. Increase the CURRENT control setting until the desired constant
current value is read on the display, or set the current limit in
advance (before connecting the load) as prescribed earlier in the
“Setting Current Limit” procedure.
8. If the load current drops below the constant current value, the CC
indicator will go off and the CV indicator will light. In this case,
the power supply automatically switches to the constant voltage
mode, and further rotation of the CURRENT control will not
increase the output current.
NOTE
OPERATING INSTRUCTIONS
Fig. 6. Typical Constant Current Operation.
20
OPERATING INSTRUCTIONS
Figure 7. Constant Voltage/Constant Current
Constant Voltage/Constant
Current Characteristic
The working characteristic of this power supply is called a constant
voltage/constant current automatic crossover type. This permits continuous transition from constant current to constant voltage modes in response to the load change. The intersection of constant voltage and
constant current modes is called the crossover point. Fig. 7 shows the
relationship between this crossover point and the load.
For example, if the load is such that the power supply is operating in
the constant voltage mode, a regulated output voltage is provided. The
output voltage remains constant as the load increases, up until the point
where the preset current limit is reached. At that point, the output
current becomes constant and the output voltage drops in proportion to
further increases in load. The crossover point is indicated by the front
panel LED indicators. The crossover point is reached when the CV
indicator goes off and the CC indicator comes on.
Similarly, crossover from the constant current to the constant voltage
mode automatically occurs from a decrease in load. A good example of
this would be seen when charging a 12 -volt battery. Initially, the open
circuit voltage of the power supply may be preset for 13.8 volts. A low
battery will place a heavy load on the supply and it will operate in the
constant current mode, which may be adjusted for a 1 amp charging
rate. As the battery becomes charged, and its voltage approaches 13.8
volts, its load decreases to the point where it no longer demands the full
l amp charging rate. This is the crossover point where the power supply
goes into the constant voltage mode.
Characteristics.
21
SERIES TRACKING OPERATION
1.
Set the
0-30 V/4
-
6.5 V
switch to the
0-30 V
When the series tracking mode of operation is selected, the positive
(red) terminal of the “B” supply output is internally connected to the
negative (black) terminal of the “A” supply. This allows the power
supply to be used as a single 0-to-60 volt power supply simply by
using the negative (black) terminal of the “B” supply and the positive
(red) terminal of the “A” supply.
In the series tracking mode, the maximum output voltage of both
the “A” and “B” supplies can be simultaneously varied with one
control. The maximum “B” supply voltage can be set to the same
value of the “A” supply by setting the “B” Coarse and Fine
VOLTAGE controls fully clockwise, so that “B” is set to 100%
tracking.
Simultaneous metering of both current and voltage can be obtained
in this mode of operation by setting one of the displays for current
metering and one for voltage metering. In this case, the output voltage
(across the two supplies) is actually double the displayed value. For
example, if the “B” display is set for voltage metering and the “A”
display for current metering, the output voltage across the “A”
positive (red) terminal and the “B” negative (black) terminal would
be double the reading on the “B” LED Display (since both supplies
are putting out the same voltage). The actual output current would be
the value read from the “A” LED Display.
8. Set the power supplies to the TRACKING SERIES mode by
engaging the INDEP/TRACK switch and releasing the
SER/PAR switch.
22
OPERATING INSTRUCTIONS
position, the “B” V/A switch to the V (voltage
metering) position, and the “A” V/A switch to the A
(current metering) position.
2. Set the “B” Coarse and Fine Voltage and
CURRENT controls to the fully clockwise position.
The maximum current is set using the “A”
CURRENT control. Follow the instructions for
“Setting Current Limit” (INDEPENDENT USE OF
“A” OR “B” SUPPLY section of this manual) using
the “A” CURRENT control.
3. Adjust the output voltage to the desired level using
the “A” VOLTAGE controls (remember that the
actual output voltage is double the reading on the
“B” LED Display ).
4. Turn off the power supply and the equipment to be
powered during hook-up.
5. Connect the positive polarity of the device being
powered to the red (+) terminal of the “A” power
supply.
6. Connect the negative polarity of the device being
powered to the black (-) terminal of the “B” power
supply.
7. Fig. 8 illustrates the grounding possibilities when
the unit is used as a 0-to-60 volt supply.
a. If the negative polarity of the equipment or circuit
being powered is also the chassis or common, it
may be grounded to earth by strapping the black
(-) terminal of the “B” supply to the green ( )
terminal of the “B” supply as shown in Fig. 8A.
OPERATING INSTRUCTIONS
Fig. 8. Series Tracking (0-to-60V) Operation Grounding Possibilities
23
OPERATING INSTRUCTIONS
F
ig. 8. Series Tracking (0
-to-60V) Operation Grounding Possibiliti
es
24
OPERATING INSTRUCTIONS
F
ig. 8. Series Tracking (0
-to-60V) Operation Grounding
a.
Similarly, the positive polarity can be grounded by
Possibilities
strapping the red (+) terminal of the “A” supply to the
green terminal of the “A” supply as shown in Fig. 8B.
b. If “split supply” operation is desired, a positive and
negative voltage with a center ground can be achieved
by strapping the black (-) terminal of the “A” supply
to the green ( ) of the “A” supply as shown in Fig.
8C. See the APPLICATIONS section of this manual
for more informat ion on “split supply” operation.
NOTE
If one of the supplied ground straps is to be used,
only use it in one of these three ways. Connecting
two ground straps could ground both the positive
and negative terminals and load down the power
supply, causing improper operation.
c. If an earth ground reference is not required, the
configuration of Fig. 8D may be used. The scheme in
Fig. 8D should also be used where it is not known
whether the chassis is common with either the positive
or negative polarity.
d. If the chassis or common of the equipment being
powered is separate from both the positive and
negative polarity power inputs, use the connection
shown in Fig. 8E.
25
9.
Observe proper polarity. If the circuit being powered is not equipped with
1.
Adjust the output voltage to the desired level
reverse polarity protection, damage to the circuit can result from reverse
polarity. Use color coded hook-up leads, for convenience in identifying
polarity, red for (+) and black for (-).
10. Make sure that the hook-up leads offer sufficient current capability and
low resistance between the power supply and the circuits being powered.
PARALLEL TRACKING OPERATION
In the parallel tracking mode of operation, both supplies are strapped
together (in parallel). This allows for a 0-30 V supply with a 4 amp current
capability. Only the “A” output terminals are used for parallel tracking
operation. In the parallel tracking mode, the “B” supply output voltage and
current track the “A” supply output voltage and current.
6. Set the power supplies to the TRACKING PARALLEL mode by
engaging both TRACKING switches (INDEP/TRACK and SER/PAR
switches).
7. Set the 0-30V/4-6.5V switch to the 0-30V position, the “A” V/A switch to
the V (voltage metering) position, and the “B” V/A switch to the A
(current metering) position. Output voltage will now be read from the “A”
LED Display. Output current is exactly double the value read from the
“B” LED Display (because each supply is providing the same amount of
current).
8. Because both voltage and current of the “B” supply track the “A” supply,
the maximum current and voltage are set using the “A” controls. Using
the “A” supply output jacks, follow the instructions for “Setting Current
Limit” (INDEPENDENT USE OF “A” OR “B” SUPPLY paragraph of this
section). Remember that the actual current output at the “A” supply
output jacks is double the reading on the “B” LED Display.
26
OPERATING INSTRUCTIONS
using the “A” VOLTAGE controls.
2. Turn off the power supply and the equipment to
be powered during hook-up.
3. Connect the positive polarity of the device
being powered to the red (+) terminal of the
“A” power supply.
4. Connect the negative polarity of the device
being powered to the black (-) terminal of the
“A” power supply.
5. Fig. 9 illustrates the grounding possibilities
when used in the TRACKing PARallel mode.
a. If the negative polarity of the equipment or
circuit being powered is also the chassis or
common, it may be grounded to earth by
strapping the black (-) terminal to the green
( ) terminal as shown in Fig. 9A.
b. Similarly, the positive polarity can be
grounded by strapping the red (+) terminal to
the green ( ) terminal as shown in Fig. 9B.
c. If an earth ground reference is not required,
the configuration of Fig. 9C may be used.
The scheme in Fig. 9C should also be used
where it is not known whether the chassis is
common with either the positive or negative
polarity.
d. If the chassis or common of the equipment
being powered is separate from both the
positive and negative polarity power inputs,
use the connection shown in Fig. 9D.
OPERATING INSTRUCTIONS
Fig. 9. Parallel Tracking Operation Grounding Possibilities
27
OPERATING INSTRUCTIONS
Fig. 9. Parallel Tracking Operation Grounding Possibilities
28
OPERATING INSTRUCTIONS
9.
Observe proper polarity. If the
circuit being powered is not
1.
Fig. 10 illustrates the grounding possibilities of the
4-6.5
V
equipped with reverse polarity protection, damage to the circuit
can result from reverse polarity. Use color coded hook-up leads,
for convenience in identifying polarity, red for (+) and black for
(-).
10. Make sure that the hook-up leads offer sufficient current
capability and low resistance between the power supply and the
circuits being powered. 10-amp test leads are available as an
optional accessory.
4-6.5 V POWER SUPPLY OPERATION
The 4-6.5V supply provides a 4.0 to 6.5V DC output with a 5 amp
current capacity. The supply is ideal for use with TTL circuits.
5. Set the 0-30V/4-6.5V switch to the 4-6.5V position and the Right
V/A switch to the V position. This sets the “A”/4-6.5V Display
to show output voltage of the 4-6.5V supply.
6. Using the Voltage Level Control to adjust the output voltage of
the 4-6.5 V supply to the desired level.
7. Turn off the power supply and the equipment to be powered
during hook-up.
8. Connect the positive polarity of the device being powered to the
red (+) t erminal of the 4-6.5V supply.
9. Connect the negative polarity of the device being powered to the
black (-) terminal of the 4-6.5V supply.
supply.
a. If the negative polarity of the equipment or circuit being
powered is also the chassis or common, it may grounded to
earth by connecting a jumper from the black (-) terminal to
either green ( ) terminal as shown in Fig. 10A.
b. Similarly, the positive polarity can be grounded by
connecting a jumper between the red (+) terminal and either
green ( ) terminal as shown in Fig. 10B.
c. If an earth ground reference is not required, the
configuration of Fig. 10C may be used. The scheme in Fig.
10C should also be used where it is not known whether the
chassis is common with either the positive or negative
polarity.
d. If the chassis or common of the equipment being powered is
separate from both the positive and negative polarity power
inputs, use the connection shown in Fig. 10D.
2. Observe proper polarity. If the circuit being powered is not
equipped with reverse polarity protection, damage to the circuit
can result from reverse polarity. Use color coded hook-up
leads, for convenience in identifying polarity, red for (+) and
black for (-).
3. Make sure that the hook-up leads offer sufficient current
capability and low resistance between the power supply and the
circuits being powered. 10-amp hook-up leads are available as
an optional accessory.
4. Set the Right V/A switch to the A position to monitor the load
current.
29
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