Edge Detection circuit causes dips in power line

Discussion in 'General Electronics Chat' started by Mellowed, May 15, 2016.

  1. Mellowed

    Thread Starter New Member

    Mar 6, 2016
    10
    2
    I'm trying to put together an edge detection unit for a delay measurement unit using the CTMU of a PIC micro-controller.

    The edge detection seems to work as shown in the image below, however i see a negative dip after the falling edge. I noticed that the dip is present in the Vcc power line as well. I think this is causing issues with my CTMU since its giving me negative readings for very short periods :(
    Is it possible to remove this dip?

    My setup is very simple for the result below. An arduino uno produced a pulse every 1us which is connected to an edge detection setup as shown below upload_2016-5-15_21-15-37.png

    I also noticed that the strange wave produced after the falling edge is visible on my PIC uP whenever a pulse is produced on a pin :(


    upload_2016-5-15_21-2-32.png
     
  2. bertus

    Administrator

    Apr 5, 2008
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  3. crutschow

    Expert

    Mar 14, 2008
    13,023
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    Is the probe ground connected close to the point you are measuring?
     
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