Offset sine wave

Discussion in 'General Electronics Chat' started by Tobias, Feb 4, 2009.

  1. Tobias

    Thread Starter Active Member

    May 19, 2008
    Thanks for helping out on the comparator, it works great. I plugged my scope into another vehicle to look at the output of the front wheel speed sensors. The sensors are on a 2009 Chevy Diesel pickup, in case anyone is wondering.

    When I first hooked up the signal wasn't on the scope. So I broadened the y-axis to 5v/mark. The signal is offset around -3v. Still learning how to correctly use my scope I started to play around with the coupling setting for the channel. The coupling was set to DC, so then I changed it to AC and the output was then centered on 0v.

    I looked up 'scope coupling' on the internet and found a handy site. Here it is for all others as new to this as I am.

    Anyways, I am going to get the pickup tomorrow to validate my findings. But, if this is the case, where the sine wave is offset a -3v, whats the trick to measuring the peaks that are above the -3v? I am playing around with an op-amp and setting it up as a 'sum op-amp'. I am adding 3v to the -3v offset sine wave that I can get with my scope and the results and not what I was expecting.

  2. Audioguru


    Dec 20, 2007
    Modern cars use a positive supply. Your 'scope is messed up since it shows -3V.
    Connect the input of the 'scope to 0V and the trace should show 0V. If it doesn't then adjust the vertical position control.
  3. Tobias

    Thread Starter Active Member

    May 19, 2008
    thanks for the reply...I will confirm tomorrow.