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Transistor voltage measurement

Discussion in 'General Electronics Discussion' started by Tommy8389, Apr 17, 2017.

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  1. Tommy8389

    Tommy8389

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    Mar 18, 2017
    By using voltmeter. How to measure the voltage of collector and emitter. Vbc is the collector voltage and Vbe is the emitter voltage? And how should my voltmeter place? Sorry for the silly question
     
  2. Herschel Peeler

    Herschel Peeler

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    65
    Feb 21, 2016
    If you want to measure the voltage between the emitter and the collector that is where the meter leads go. Is your question more complicated? Start with a data sheet for the transistor in question.
     
  3. Audioguru

    Audioguru

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    678
    Sep 24, 2016
    Vbc is the voltage from the base to the collector.
    Vbe is the voltage from the base to the emitter.
    Vce is the voltage from the collector to the emitter.
     
  4. duke37

    duke37

    5,364
    769
    Jan 9, 2011
    The circuit will have a ground connected to many stages.
    Measure the voltage between ground and emitter.
    Measure the voltage between ground and base.
    Measure the voltage between ground and collector.

    Some subtraction will give the voltages required.
    With an npn transistor, the voltages relative to ground will rise from emitter to base to collector and there is likely to be about 0.6V emitter/base.
     
  5. Tommy8389

    Tommy8389

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    0
    Mar 18, 2017
    I placed my voltmeter's positive at the base and the negative at collector. When the transistor is "OFF". I get negative voltage (-0.78v). When the transistor is "ON". The voltage is 0.72v. can you explain for me why? Or i placing it at wrong polarity? Thanks.
     
  6. Bluejets

    Bluejets

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    Oct 5, 2014
    NPN or PNP?
     
  7. Tommy8389

    Tommy8389

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    Mar 18, 2017
    Npn
     
  8. Tommy8389

    Tommy8389

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    0
    Mar 18, 2017
    Ok thanks guys. I found out why there is a negative voltage occured when transistor is off. After i read through the cut-off mode.
     
  9. BobK

    BobK

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    1,686
    Jan 5, 2010
    Why are you measuring from the collector to the base? The more useful measurements are from the emitter to the base and from the emitter to the collector.

    Bob
     
  10. Audioguru

    Audioguru

    3,041
    678
    Sep 24, 2016
    We do not have a clue about your transistor circuit because you did not attach its schematic to this thread. The schematic will show the part number of the transistor, the supply voltage and the resistor values. Something (maybe a switch?) on the schematic will turn the transistor on and turn it off. Then we will know all the details.
     
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