Power Designs 2005 Service Manual
Description
New high-stability, low-noise silicon semiconductor devices
and advanced solid-state circuit technology are the basis for
this unusually stable voltage regulator. The improved
performance of the Model 2005 permits dial readout of the
output voltage to five places. Interpolation of the last place is
provided by a potentiometer with a resolution of 10 microvolts.
Conventional, more complex chopper techniques for DC
amplifier stabilization are avoided by maintaining critical
amplifier stages and a specially processed zener diode voltage
reference in a temperature-controlled oven. The design
simplicity results in a low-cost unit, half the size and weight of
comparable instrumentation.
Design Features of the Model 2005
• Self-restoring electronic overload and short-circuit
protection.
• All silicon-semiconductor regulator system.
• Critical semiconductors and components maintained
at constant ambient in temperature-controlled oven.
• Accurate remote programming at 1000 ohms-per.volt.
• Front and rear access to output terminals.
• 100 hour pre-aging of power supply before test and
calibration. Individual calibration data furnished with
each unit.
• Line and load circuits separately fused. Accessible at
rear. Performance specifications based on anticipated
ratings after 5 years service.
• "Controlled-Parameter" semiconductor program
• Calibrated decade voltage readout to four significant
figures at outputs below 10 volts, to five significant
figures above 10 volts. Interpolation of the last place
is provided by a potentiometer with 10-microvolts
resolution.
• Provisions for rear-panel zero calibration (may be
used to offset lead drop during remote sensing).
• Adjustable current limiting.
insures long life expectancy. Features "controlled
avalanche" silicon rectifiers and power transistors,
pre-aged zener voltage references and transistors,
noise-testing techniques for establishing predictable
device reliability, derating to 50% of rated voltage and
current, etc.
• Modular package construction suitable for rack
mounting. Single or dual mounting in 5¼"x 19" panel.
See Cat. RPA-62 for rack panel adapters.
General Description
• OUTPUT - 0 to 20 VDC, continuously adjustable, at 0 to 500 MA.
• INPUT - 105 to 125 V, 50 to 440 Hz, 40 W max. (Including oven heater).
• CALIBRATION AND ACCURACY - Two dual, concentric, decade switches provide dial
readout to four places with an accuracy of 0.1% ± 1 MV at outputs below 10 V. A 1-MV
range, single-turn potentiometer permits interpolation of the last place. This potentiometer
has a resolution of 10 uV. A toggle switch extends the range of the dial readout from 10 to
20 V, without affecting resolution or accuracy (five-place readout). An illuminated
indicator identifies the range in operation.
• REGULATION - Output voltage change less than 100 uV (at sense connection points) for
line or load variations over the operating range.
• RIPPLE AND NOISE - Less than 100 uV peak-to-peak.
• SOURCE IMPEDANCE - Less than 0.2 milliohm at DC, 0.04 ohm at 20 KHz, 0.5 ohm at
1 MHz.
• RECOVERY TIME - Less than 10 uS to return to within 250 uV or 0.005% (whichever is
greater) of the set voltage for a 10% to 100% step change in rated load; less than 40 uS to
return with 100 uV.
• OPERATING TEMPERATURE RANGE - 15 to 4 °C ambient; 0 to 60 °C ambient with
reduced accuracy.
• TEMPERATURE COEFFICIENT - DC output voltage change less than 0.001% or 50 uV
(whichever is greater) per °C over the range of +15 to +45°C; less than 0.002% or 100uV
(whichever is greater) per °C from 0 to +15°C and +45 to +60 °C.
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• STABILITY - Better than 0.001% + 100 MV/8 hrs.; better than 1 MV/wk (at constant
ambient temperature, load and line voltage, after warmup).
• OUTPUT TERMINALS - Three front-panel binding posts and rear-panel barrier block.
Either positive or negative output terminal may be grounded.
• METER - Front-panel volt-ammeter permits monitoring output voltage or current with an
accuracy of ±2%.
• REMOTE SENSING - Two terminals on rear-panel barrier block are provided for remote
sensing of voltage at the load.
• REMOTE PROGRAMMING - Rear terminals are provided for remote programming of
the output voltage at 1000 ohms-per-volt. Accuracy of programming is better than 0.01%
of value of resistance (including connecting leads).
• CURRENT LIMITING - The output current can be limited to any value from 0 to 500
MA by a front-panel control. A push-button permits easy adjustment without the need for
shorting the output terminals.
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SECTION 1
GENERAL DESCRIPTION
1-1. DESCRIPTION
The Model 2005 is a precision DC power source designed to supply an extremely stable 0 to 20 volt, 0 to
500 milliampere output. The instrument combines the accuracy of a precision calibrator with the power
capability of a general-purpose regulated supply. Two dual, concentric decade switches provide a digital
readout of the selected output voltage to within 0.1% +1 millivolt of the selected value. A 1-millivolt
range, single-turn potentiometer permits interpolation of the last place. This potentiometer has a
resolution of 10 microvolts. A toggle switch selects the range of the dial readout; either from 0 to 10
volts, or from 10 to 20 volts. The output voltage of the supply may be remotely programmed with the
same accuracy, using an external resistance. The supply also includes provisions for remote sensing of the
output voltage at the load. Compact and light, the power source is self-contained in a portable housing
designed for bench use. The modular construction of the Model 2005 makes it suitable for rack mounting.
Panel adapters are available for mounting one or two units in a standard 19-inch rack having a panel
height of 5 1/4 inches.
1-2. ELECTRICAL SPECIFICATIONS
Refer to Table 1 for a complete list of electrical specifications.
TABLE 1. ELECTRICAL SPECIFICATIONS
Parameter Value
Output 0 to 20 volts DC, continuously adjustable, 0 to 500 milliamperes
105 to 125 volts, 50 to 440 Hz, 40 watts (nominal) Regulation DC voltage change less
Input
Ripple and
Noise
Source
Impedance
Recovery Time
Stability
Temperature
Coefficient
Calibration
Accuracy
than 100 microvolts for line variations of ±10% or load variations of 100% (at sense
lead connection points)
Less than 100 microvolts peak-to-peak
Less than 0.2 milliohm at DC, 0.04 ohm at 20 KHz, 0.5 ohm at 1 MHz
Less than 10 microseconds to return to within 250 microvolts or 0.005% (whichever is
greater) of the set voltage for a step change in rated load (1 microsecond rise time) of
10% to 100% or 100% to 10%; less than 40 microseconds to return to within 100
microvolts
Better than 0.001% +100 microvolts per 8 hours; better than 1 millivolt per week (at
constant line, load and ambient temperature after warm-up).
DC output voltage change less than 0.001% or 50 microvolts (whichever is greater) per
°C over the range of +15 °C to +45 °C, less than 0.002% or 100 microvolts (whichever
is greater) per0 °C from °C from 0 °C to +15°C and from +45 °C to +60 °C
Better than 0.1% +1 millivolt
Current
Limiting
0 to 500 milliamperes continuously adjustable by a front panel control. A front panel
push button permits easy adjustment without shorting the output terminals.
1‐1
Output Terminals
Front Panel Three insulated binding posts for positive output, negative output, and chassis ground
Rear Panel
Remote Sensing
Screw terminals on a molded barrier block for positive output, negative output, chassis
ground, remote voltage programming and remote sensing.
Two terminals are provided on a rear panel barrier block for remote sensing of the
voltage at the load.
Parameter Specifications
Rear panel barrier block terminals are provided for remote programming of the output
Remote
Programming
voltage. The ratio of the programming resistance to the output voltage is 1000 ohms
per volt. The programming accuracy is better than 0.01% of the resistance value,
including the resistance of the programming leads.
Front panel volt-ammeter permits monitoring output voltage or current with an
Metering
accuracy of ±2% of full scale.NOTE: This accuracy is considerably less than that of the
power source.
Circuit
Protection
The AC line and DC load circuits are separately fused. The fuses are accessible at the
rear of the unit.
Indicator Lamps
AC Lamp Lights when AC toggle switch is set to ON and power is applied to the unit.
Lights when AC input is applied and oven heater is energized (operates even when AC
OVEN Lamp
toggle switch is turned off). Lamp cycles on and off as oven maintains constant
temperature environment for critical components.
+10 V Lamp
Lights when RANGE switch is set to 1O-20V position to indicate that output is 10
volts plus the dial readout.
1-3. MECHANICAL SPECIFICATIONS
• Dimensions : 8-3/8 inches wide by 4-3/4 inches high by 8-
• Weight : 9 pounds.
• Finish : The panel is finished in brushed aluminum and has
15/16 inches deep behind the front panel.
etched black lettering. The housing is finished in blue-gray
vinyl enamel. The chassis and bottom plate are gold iridite.
1‐2
SECTION 2
2) INSTALLATION AND OPERATION
2-1 INSTALLATION
a) Laboratory Bench . The Model 2005 is a portable unit designed for bench use. No
preliminary processing or special unpacking procedures are required. The power source is
ready for operation as shipped from the factory.
b) Rack Mounting . Panel adapters are available for mounting one or two units in a standard 19-
inch relay rack. Hardware kits are provided with each panel adapter. The power source is
fastened to the rear surface of the adapter with the black anodized rivnuts in each corner of its
front panel. If the rubber bumper feet interfere with the assembly of the equipment to the
rack, they may be removed by disassembling the bottom plate of the power source and
unscrewing them.
2-2 OPERATION
a) Operating Procedures:
(i) Ensure that the power source is turned off and the shorting links are connected between
the following rear-panel terminals: DC+ and S+; S+ and RV; and S- and DC-.
(ii) Set the CURRENT LIMIT ADJ control fully clockwise.
(iii) Connect the AC line cord to a source of 105 to 125 volts, 50 to 440 Hz. NOTE: The
OVEN indicator will normally light as soon as line voltage is applied to the unit, even
when the power source is turned off. The indicator will remain lighted until the oven
reaches operating temperature (approximately 10 minutes). The indicator will cycle on
and off as the oven maintains a constant- temperature environment for critical circuit
components.
(iv) Read the information in paragraphs b through e to connect for remote sensing, series
operation, remote programming of the output voltage, or current limiting.
(v) Set the AC switch to ON.
(vi) Set the output voltage to the desired value, using the front panel dials. Set the
VERNIER control to zero if interpolation between 1 millivolt steps is not desired.
(vii) Connect the DC+ and DC- terminals (on the front or rear panel) across the load. If
desired, connect the positive or negative output terminal to ground.
b) Sensing: The regulator circuit maintains the potential between the sense leads (s+ and S-) at
the set output voltage. When these leads are connected to the positive and negative output
terminals, the power source is connected for local sensing. When the sense leads are
connected to the load, the source is connected for remote sensing. Remote sensing is used
when an appreciable voltage drop is anticipated in the leads connecting the positive and
negative output terminals to the load. The Model 2005 is connected for local sensing when
shipped from the factory. For remote sensing, proceed as follows:
(i) Remove the shorting links from between the rear panel DC+ and S+ terminals and from
between the DC- and S- terminals.
(ii) Connect the DC+ and DC- leads across the load.
(iii) Connect the S+ and S- leads to the positive and negative sides of the load, respectively.
Run the sense leads as a tightly twisted, shielded pair. Connect the shield to the G
(chassis ground) terminal to minimize output ripple
(iv) Turn on the Model 2005.
2‐1
c) Series Operation: As many as four Model 2005 units may be connected in series to provide
up to 80 volts. Connect the positive DC output terminal of one supply to the negative output
terminal of the next, in the same manner as connecting batteries in series. The ground
terminals on all units may be left floating or they may be tied together and connected to either
the most positive or the most negative output terminal. To insure optimum voltage regulation,
disconnect the shorting links between all S+ and DC+ output terminals except those at the
most positive potential. Then connect jumper wires between each S+ terminal and the Sterminal on the next more positive power source. In this way, the voltage drops in the leads
connecting the power sources will be compensated for by the regulator circuits of the
individual units. For remote sensing, proceed as directed above, except connect the most
positive and most negative S+ and S- leads across the load.
d) Remote Voltage Programming: The output voltage can be programmed remotely by an
external fixed or variable resistance. Proceed as follows:
(i) Turn off the power source, set all output voltage controls to zero and set the RANGE
switch to 0 -10V.
(ii) Remove the shorting link from between the rear panel RV and S+ terminals.
(iii) Select a programming resistance by multiplying the desired output voltage by 1000 (the
programming constant is 1000 ohms per volt). A constant current of 1 milliampere will
flow through this resistance, and its wattage rating should be chosen to minimize drift
due to heating.
(iv) Connect the external programming resistance between the RV and S+ terminals using
twisted, shielded wire. Connect the shield to the G (chassis ground) terminal to minimize
output ripple.
(v) Turn on the power source.
CAUTION: IF THE REMOTE PROGRAMMING CONNECTIONS ARE OPENED
WHILE THE SUPPLY IS OPERATING, THE OUTPUT VOLTAGE WILL RISE
SLIGHTLY ABOVE THE SET VALUE. WHEN A SWITCH IS USED TO SELECT
RESISTORS FOR OUTPUT VOLTAGE PROGRAMMING, IT SHOULD HAVE
SHORTING TYPE CONTACTS TO AVOID VOLTAGE SPINES.
e) Current Limiting: The maximum output may be limited to a value below 500 milliamperes as
follows:
(i) Turn on the power source and set the meter switch to MA.
(ii) Depress the CURRENT LIMIT SET button and adjust the CURRENT LIMIT ADJ
control until the meter indicates the maximum desired output current. Release the
CURRENT LIMIT SET button.
2‐2
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