INSTRUCTION MANUAL Model 1744A & 1745A 0-35 V, 0-10 A DC POWER SUPPLY With Dual Displays
TEST INSTRUMENT SAFETY WARNING 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.
TABLE OF CONTENTS Page Page TEST INSTRUMENT SAFETY --------------inside front cover APPLICATIONS------------------------------------------------ 20 General -------------------------------------------------------- 20 Electronics Servicing ---------------------------------------- 20 Electronics Manufacturing ---------------------------------- 20 Electronics Design Lab -------------------------------------- 20 Electronics Education---------------------------------------- 21 Battery Charging ----------------
INTRODUCTION The B+K Precision Models 1744A &1745A DC Power Supplies are high quality, general purpose dc power sources. They provide 0-35 volts dc output, adjustable with both coarse and fine voltage controls for precise settability. The current output is 0-10 amps, adjustable with both coarse and fine current controls (model 1745A). Two large LED meters continuously monitor the output voltage and current (model 1745A). The VOLTAGE meter is green, while the CURRENT meter is red (model 1745A).
FEATURES LED INDICATORS 0-35 VOLTS Act as pilot light and identify mode of operation and metering. Continuously variable over 0-to-35 volts with coarse & fine controls. PRE-REGULATOR 0-10 AMPS Limits internal dissipation for higher reliability. 0-to-10 amps current rated for continuous duty at full output current. Coarse and fine current adjust controls. ISOLATED OUTPUT LABORATORY QUALITY Either polarity may be floated or grounded. Excellent regulation, low ripple.
SPECIFICATIONS OUTPUT VOLTAGE: adjustment. 0 to 3 5 VDC, coarse and fine OUTPUT CURRENT: adjustment. 0 to 10 A, coarse and fine CONSTANT VOLTAGE OPERATION Voltage Regulation Line (108 -132 V): Load (no load to full load): ≤0.2% +2 mV ≤0.04% + ≤0.04% + 2 mV Recovery Time: ≤100 μs typical. Ripple Voltage RMS: ≤1 mV. Temperature Coefficient (0° to +40 °C): ≤300 PPM/°C 4 digit Green LED Display 0 to 99.99 V. (0.5% + 9 digits) Ammeter Hi Range: Accuracy: 4 digit Red LED Display 0 to 9.999 A.
SPECIFICATIONS WEIGHT: TEMPERATURE RANGE Operation: Storage: 0° to +40° C, ≤75% R.H. -15° to +70° C,≤85% R.H. DIMENSIONS (HxWxD): 5.7” x 10.5” x 15” (145 x 267 x 38 mm) 27 lb. (12.25 kg) ACCESSORIES SUPPLIED: Instruction Manual, Spare Fuse NOTE: Specifications and information are subject to change without notice. Please visit www.bkprecision.com for the most current product information.
CONTROLS AND INDICATORS INDICATORS CURRENT CONTROL Either the “CC” or “CV” and the LED indicators will be lit whenever the unit is operating, thus serving as a pilot light. The unit automatically changes from CV to CC operation when the preset current limit is reached. 1. C.C. (Constant Current) Indicator. Red LED lights in constant current mode. Unit regulates output current at value set by CURRENT controls. 2. C.V. (Constant Voltage) Indicator. Green LED lights in constant voltage mode.
CONTROLS AND INDICATORS REAR PANEL CONTROLS 7. Fuse. 8. Power Cord. 9. 110/220 Line Voltage Conversion Switch. Figure 1. Front Panel Controls and Indicators. Figure 2.
OPERATING INSTRUCTIONS SAFETY PRECAUTIONS Do not exceed the voltage rating of the circuit being pow ered. Most transistors and integrated circuits will not withstand voltage of 35 volts. 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 is no need to worry about voltage spikes or overshoot damaging the equipment under test.
OPERATING INSTRUCTIONS Figure 3 (A and B). Grounding Possibilities.
OPERATING INSTRUCTIONS Figure 3 (C and D). Grounding Possibilities.
OPERATING INSTRUCTIONS c. If an earth ground reference is not required, the configuration of Fig. 3Bmay 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 weirsd@earthlink.net inputs, use the connection shown in Fig. 3D. 5. Observe proper polarity.
OPERATING INSTRUCTIONS 5. . Increase the VOLTAGE setting until the Voltage LED display reads the desired value. The FINE control permits easier setting to a specific value. 6. Note the load current on the Current LED display. 7. 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 TYPICAL CONSTANT CURRENT OPERATION 1. Before connecting the device to be powered to the power supply, determine the maximum safe voltage to be applied, and set the VOLTAGE controls to obtain that voltage reading on the Voltage LED display. 2. Determine the desired constant current value. 3. Set the Coarse and Fine 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.
OPERATING INSTRUCTIONS 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.
OPERATING INSTRUCTIONS Figure 8. Connecting Two Power Supplies in Series.
OPERATING INSTRUCTIONS Figure 9. Connecting Two Power Supplies in Parallel.
OPERATING INSTRUCTIONS CONNECTING TWO POWER SUPPLIES IN PARALLEL If the current equalizing resistors are not well matched, it is preferable that the voltages be slightly unbalanced to achieve current balance. Be sure that the supplies are adequately balanced so that both remain in the CV mode. Two power supplies may be connected in parallel to double the maximum load current.
APPLICATIONS GENERAL These model power supplies have a very wide variety of applications in electrical and electronics servicing, engineering laboratories, manufacturing and testing facilities, schools, and home hobbies. The power supply output is fully adjustable from 0 to 35 volts and 0 to 10 amps. This flexibility makes them suitable for most applications requiring a dc power source. The equipment being tested may contain its own power supply and operate from ac power.
APPLICATIONS ELECTRONICS DESIGN LAB BATTERY CHARGING The technician or engineer working in an engineering laboratory requires a dc power supply to power breadboard and prototype circuits. This power supply is ideal because it monitors output current, output voltage, limits current to protect the circuit, is adjustable over a wide range, and has excellent regulation and very low ripple.
MAINTENANCE WARNING LINE VOLTAGE CONVERSION, INTERNATIONAL UNITS The following instructions are for use by qualified personnel only. To avoid electrical shock, do not perform any servicing other than contained in the operating instructions unless you are qualified to do so. The primary winding of the power transformer is tapped to permit operation from 120/220/230 or 240 VAC, 50/60 Hz line voltage.
MAINTENANCE CALIBRATION If readjustment is required, use the following procedure. Locations of the adjustments are shown in Fig. 11. 1. Set the front panel controls of the Model 1743BA as follows: Coarse and Fine VOLTAGE controls fully clockwise. Coarse and Fine CURRENT controls fully clockwise. Power switch to On. 2. Connect the Multimeter to measure the voltage at pin 14 of IC2 with respect to the front panel red (+) output jack. Adjust R21 for -5.00 volts on the Multimeter. 3.
MAINTENANCE Figure 11. Location of Adjustments.
Service Information Warranty Service: Please return the product in the original packaging with proof of purchase to the address below. Clearly state in writing the performance problem and return any leads, probes, connectors and accessories that you are using with the device. Non-Warranty Service: Return the product in the original packaging to the address below. Clearly state in writing the performance problem and return any leads, probes, connectors and accessories that you are using with the device.
Limited Two-Year Warranty B&K Precision Corp. warrants to the original purchaser that its products and the component parts thereof, will be free from defects in workmanship and materials for a period of two years from date of purchase. B&K Precision Corp. will, without charge, repair or replace, at its option, defective product or component parts. Returned product must be accompanied by proof of the purchase date in the form of a sales receipt. To obtain warranty coverage in the U.S.A.
TEST INSTRUMENT SAFETY (continued from inside front cover) 4. If possible, familiarize yourself with the equipment being tested and the location of its high voltage points. However, remember that high voltage may appear at unexpected points in defective equipment. 5. Use an insulated floor material or a large, insulated floor mat to stand on, and an insulated work surface on which to place equipment; and make certain such surfaces are not damp or wet. 6.
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