Need a quick & dirty curve tracer?

Discussion in 'The Projects Forum' started by ErnieM, Apr 3, 2012.

  1. ErnieM

    Thread Starter AAC Fanatic!

    Apr 24, 2011
    So I found I needed a curve tracer right away and we had none available, and no source to rent one from for any price we thought reasonable. So I threw one together.

    Specifically, we needed to see the knee region of a 36V zener up to 7 mA of current. Here's what I did:

    That goes to a scope in X-Y mode. T1 & T2 & D1 give about a 75V peak half wave rectified sine wave. Nice pulses to drive the horizontal. R1/R2 and Q1 (a darlington) allows the peak applied voltage to be varied.

    Then R4 is used as a sense resistor. When 7 mA is flowing a 0.7V signal develops across the resistor.

    Two transformers were used as I was limited to off the shelf at Radio Shack. Total BOM was under 30 bucks.

    Made a very useful and instant test for a bunch of diodes.

    If I had thought of it at the time I would have reversed the SCOPE B and (scope) RTN signals and used the invert on channel B: That would have kept the current sense voltage out of my test voltage probe.
  2. R!f@@

    AAC Fanatic!

    Apr 2, 2009
    U are good.

    Suggest the mods to move this into the completed section