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Transistor Test Circuit

IP.com Disclosure Number: IPCOM000097613D
Original Publication Date: 1961-Mar-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 33K

Publishing Venue

IBM

Related People

Wajda, WW: AUTHOR

Abstract

The circuit determines the D. C. characteristics which are equivalent to the dynamic characteristics at the knee of saturation for any specified collector current.

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Transistor Test Circuit

The circuit determines the D. C. characteristics which are equivalent to the dynamic characteristics at the knee of saturation for any specified collector current.

The circuit includes a constant current generator 1 as the collector supply for the transistor 2 under test. A dynamic supply 3 and an adjustable D. C. supply 4 are connected, alternately, through a vibrating switch 5 to the base of the transistor. The contactor of 5 is closed on its contact B when de-activated. It has an unequal dwell, favoring the point B, to limit power dissipation when the transistor is being swept into the active region. A Zener diode 6 protects the apparatus when 2 is removed. The instruments are an ammeter 7 for reading D.
C. base current, a voltmeter 8 for reading the collector emitter voltage, and an oscilloscope 9. The latter displays, in superposition, the dynamic curve 10 of the base current versus collector emitter voltage, and a dot 11 representative of the same values for D. C. operation.

When the dot 11 is moved by adjustment of supply 4 to the knee (edge of saturation) of curve 10, vibrating switch 5 is arrested on its contact B. Then the
D. C. values of base current and collector emitter voltage, corresponding to the edge of saturation at the collector current determined by the generator 1, are read from meters 7 and 8, respectively.

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