5 Application Examples114 Keysight U1401B User’s and Service GuideDetermining transistor hfeFor NPN-type BJT1 Turn the rotary switch to the / position.2 Connect the base to the positive output terminal.3 Connect the emitter to the negative output terminal and the negative terminalof a DC power supply (which supplies the required V DD).4 Connect the collector to the negative input terminal.5 Connect the positive terminal of the DC power supply to the positive inputterminal through a resistor.6 Output a constant current of +1.000 mA (this is IB ).7 Read the measured current value (this is I C ).For PNP-type BJT1 Turn the rotary switch to the / position.2 Connect the base to the positive output terminal.3 Connect the collector to the negative output terminal and the positive terminalof a DC power supply (which supplies the required V DD).4 Connect the emitter to the negative input terminal.5 Connect the negative terminal of the DC power supply to the positive inputterminal through a resistor.6 Output a constant current of -0.500 mA (this is IB ).7 Read the measured current value (this is I C ).The transistor h fe is calculated as the ratio of IC over I B.NOTE If you wish to obtain the correct results, please adjust the values of VDD and I Baccording to the conditions specified by the transistor manufacturer.
