1. Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.
    Dismiss Notice

Help with dynamic test load

Discussion in 'Electronic Projects Design/Ideas/Reviews' started by imix500, Feb 22, 2009.

  1. imix500

    imix500 Member

    Joined:
    Feb 22, 2009
    Messages:
    105
    Likes:
    1
    Location:
    Putnam, NY
    I'm pretty sure I tried doing that in the beginning. Is it possible that the set load current will vary with applied voltage by tying the collector to IN+ ? That's what I seem to remember.
     
  2. Roff

    Roff Well-Known Member

    Joined:
    May 16, 2003
    Messages:
    7,757
    Likes:
    89
    Location:
    Idaho, USA
    No. The emitter currents from T1 and T2 flow through the current sense resistor (R19). You want the collector currents of T1 and T2 to flow through the load, so the only error is T1 base current. This assumes you are applying a known voltage on the control input (Vctrl), and want to be able to calculate the output current as Vctrl/R19. I realize you are not doing this.
    Nevertheless, it should still solve your high current problem caused by removing the load.
     
    • Like Like x 1
  3. imix500

    imix500 Member

    Joined:
    Feb 22, 2009
    Messages:
    105
    Likes:
    1
    Location:
    Putnam, NY
    Excellent. Thanks!
     
  4. dave

    Dave New Member

    Joined:
    Jan 12, 1997
    Messages:
    -
    Likes:
    0


     
  5. imix500

    imix500 Member

    Joined:
    Feb 22, 2009
    Messages:
    105
    Likes:
    1
    Location:
    Putnam, NY

    So it's been two years and I just realized I never reported back. The test load has been in use at both home and mostly work without a problem. At this point I haven't needed to build the larger one although I plan to when I have time. Here's a couple shots of it.

    Thanks Roff for all your help!
     

    Attached Files:

  6. power58

    power58 Member

    Joined:
    Nov 20, 2008
    Messages:
    36
    Likes:
    0
    Location:
    IL.
    Looks great ! Nice job, Thanks for posting
     

Share This Page