Help on loop back cable?

Discussion in 'General Electronics Chat' started by DIYSteve, Aug 21, 2012.

  1. DIYSteve

    Thread Starter New Member

    Oct 27, 2011
    I've been using the free oscilloscope program Visual Analyzer (VA). Available here:

    I used to be able to play a video and analyze the audio track with the VA. This was helpful as a tachometer for motor experiments. That was with my old laptop.

    I have a new laptop, now and I cannot find a way to connect the audio out via settings to the program's input.

    Instead it always comes up using the laptop's microphone input as a signal source.

    Accidentally the other day, I realized that if I cranked the sound level up through the laptop's internal speaker (instead of a headphone), the internal microphone would pick it up and display it on the VA.

    This is pretty crude, but it works.

    I would like to connect the microphone input to the headphone output to do the same thing electrically. But I'm afraid of overdriving/impedance mismatching somehow letting the magic smoke out of the laptop.

    So I thought I'd ask first for advice here first.

    Also not sure if typical mic jack is stereo or mono on a modern laptop, if and when I do make up a cable.

    Thank you for your help.