need help with transistors

Discussion in 'General Electronics Chat' started by vaidi, Mar 9, 2012.

  1. vaidi

    Thread Starter New Member

    Mar 9, 2012
    Hi, i just want to ask for some questions with transistors.

    1. How will i know if it is NPN or PNP?
    2. when i measured the resistance of the transistor terminals using DMM set to ohms, the value of emitter-collector is 0Ω. emitter-base is 36.85 mΩ. collector-base is 37.20mΩ. are these correct?
  2. crutschow


    Mar 14, 2008
    1. Measure the base-emitter junction resistance. If it has a lower resistance with positive voltage applied to the base it is NPN, otherwise it is PNP.

    2. The actual values you measure depend upon the meter. But an emitter-collector resistance of zero indicates a zapped transistor.
    Last edited: Mar 10, 2012
    vaidi likes this.
  3. wmodavis

    Distinguished Member

    Oct 23, 2010
    And just for your information the correct abreviation for Megohm is capital not lower case. Lower case mΩ is used for milliohm. Big difference. Using correct abbreviations will help you communicate more precisely.
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  4. Audioguru


    Dec 20, 2007
    My multimeter uses 200mV to measure resistance so it does not forward bias a silicon junction. It uses "diode test" to apply up to 3.5V then it shows the forward voltage, not resistance.

    I think the OP is measuring a shorted transistor.