Which Is Which???

Discussion in 'HO Scale Model Trains' started by msh, Jul 9, 2002.

  1. msh

    msh Member

    How does one use his tester to determine which connector on an unmarked DC power supply is positive and which is negative?
  2. cidchase

    cidchase Active Member

    Hi Mike,
    If your tester is a meter and is designed for DC measurements it will have or should have two test leads, one red and one black. The jacks or connections to the meter should be either color coded (like the leads), red for positive (+) and black for negative (-), or else otherwise identified as (+) and (-).
    Use the voltage scale on your meter. If your tester is digital it should read a number (the voltage reading) when the leads are touched to the power supply terminals. If the reading has a (-) sign before it, your leads are reversed (black to the positive and red to the negative). This will not hurt a digital meter.
    If your tester has a needle or pointer, the needle will peg backwards if the leads are reversed. The needle will only swing up to a reading above zero if the red (+) lead is on the positive terminal of the power supply and the black (-) lead is on negative.
    Mike, I don't know if this covers your particular tester. If not, repost with more detail of the instrument.

    from Olive Branch,
    :D :D :D
  3. msh

    msh Member

    Thank you for your input. I've got a digital meter and look forward to putting this to work tonight when I get home.

Share This Page