AC amplitude changing with phase

Discussion in 'General Electronics Chat' started by hunterage2000, May 25, 2012.

  1. t_n_k

    AAC Fanatic!

    Mar 6, 2009
    Hi hunterage2000,

    Sometimes it helps to take a different approach.

    I suggest for the moment you forget the AC input issue and focus on whether the bridge + instrumentation amplifier setup behaves correctly.

    The amplifier will work equally well with DC input values.

    I'd try the following ...

    With the bridge in one condition [e.g post #31 left] replace the AC source with a DC excitation voltage of some value - let's say 1.5V - with the same polarity as shown on your AC source. Measure the amplifier DC output. Swap the bridge to the alternate case [post #31 right] with the DC excitation unchanged. Measure the amplifier DC output again. Do you see a consistent result with the same DC magnitude output but with a polarity reversal? If you do then the amplifier is OK.