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Power Supply Tester With Control for Load Simulating Transistor

IP.com Disclosure Number: IPCOM000085079D
Original Publication Date: 1976-Feb-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 2 page(s) / 27K

Publishing Venue

IBM

Related People

Dannenberg, RE: AUTHOR

Abstract

Power transistor 2 forms a load for testing a power supply 3. A current regulator 4 provides base current to transistor 2 according to the setting of a potentiometer 5 for operating the power supply 3 with a selected load current. Potentiometer 5 may be part of a digital-to-analog converter that receives digital signals from a program running on a digital computer, so that a selected sequence of tests can be run.

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Power Supply Tester With Control for Load Simulating Transistor

Power transistor 2 forms a load for testing a power supply 3. A current regulator 4 provides base current to transistor 2 according to the setting of a potentiometer 5 for operating the power supply 3 with a selected load current. Potentiometer 5 may be part of a digital-to-analog converter that receives digital signals from a program running on a digital computer, so that a selected sequence of tests can be run.

It is undesirable to operate transistor 2 as a high-current load during initial start-up of regulator 4 when the regulator voltage has a low value. Differential amplifier 6 and diode 7 control the current regulator 3 so that transistor 2 has the desirable volt-ampere characteristics of a linear passive circuit element during start-up. Amplifier 6 produces at its output 8 a measure of the output voltage of power supply 3.

At the normal output voltage of the power supply 3, the voltage at output 8 is more positive than the voltage set by potentiometer 5, and diode 7 turns off and isolates amplifier 6 from the current regulator 4. During power supply start-up, the voltage at output 8 is less than the normal voltage of the potentiometer 5, and diode 7 turns on to control current regulator 4 according to the output voltage of the amplifier 6. Thus base current to the power supply 3 and the power supply load 2 has a selected uniform impedance value during start-up.

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