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Multimeter functioning [newbie question]

Discussion in 'Electronic Basics' started by Neutron, Sep 15, 2005.

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  1. Neutron

    Neutron Guest

    Hi, total newbie to electronics, I just built a kit which worked first go
    fortunately for me, all I basically understood was that capacitors store a
    charge and resistors resist the current.

    The kit said the test the voltages and so I went ought and bought this
    cheapie multimeter . . .

    I didn't need to use it as the kit worked fine even with my rudimentary
    soldering skills, but I identified the parts correctly and even if my
    understanding of electronics was minimal it was a rather mechanical process.

    With the multimeter, the instructions are pretty basic with this thing
    could anyone point me in the right direction of understanding it's
    functionality, once I touch the red and the black pointie things numbers
    appear and I'm lost from there,

    Thanks in advance for your help.
  2. To get familiarized with your new mmeter, you could try using it on
    known sources first. Try testing a 9V battery on the DC 20 volts range.
    I see by looking at the picture that the ranges are not labeled "DC"
    "AC" etc. The upper right quadrant is DC volts (symbol is a solid bar
    over a dotted line to indicate you are measuring some voltage on one
    side of zero volts). The reading will be close to 9 volts for a good
    battery. Try using the AC volts range (lower right quadrant -- symbol
    is a sideways "S" to indicate you are measuring a voltage that
    alternates between positive and negative in a regular cycle) to test a
    wall socket (110 to 120 volts). Shorting the leads together on the ohms
    scale (upper left, with the Greek letter omega -- the symbol for ohms)
    should give you a reading o zero (if not, there is usually a trim
    control to adjust for zero). The lower left quadrant ("A") is the amps
    range. This is used to measure current by placing the meter leads in
    series with the circuit. Use this range with caution (wait until you
    have more experience with the meter). In all cases, make sure the meter
    is in a high enough range to avoid an over range reading. In other
    words, choose a range that is bigger than the voltage you expect to
    read. When testing an unknown, start at the highest range and work down
    MAY DAMAGE YOUR METER. Also, remember the one cardinal rule of
    multimeters -- NEVER MEASURE VOLTAGES ON THE OHMS SCALE. Have fun!

    Remember -- All things run on smoke
    If you let the smoke out, it won't work anymore.
  3. One additional note -- The 110-120 volts AC I spoke of above is the
    standard in the U.S. I see you ordered from a NZ company. Does this
    mean you are not in the U.S.? If so, your wall socket voltages may be
    different (higher). Set your range accordingly. That "world wide"
    thing caught me again.

  4. Neutron

    Neutron Guest

    Thanks for all your help !!!! :)

    Yeah there was a warning on the (lacking) instructions about measuring that
    sort of thing.
    There's also a "hFE" setting on the bottom as well on the lower right
    qudrant, and another setting that looks like this "->|-" (sorta). Could you
    suggest what these might be for ?

  5. Neutron

    Neutron Guest

    Actually, I do have to adjust the voltage on T2 and T4 so this will assist !
    (It's a theremin kit BTW)
  6. "Neutron" () writes:

    Was there no manual?

    The "->|-" I bet looks like the common diode symbol, and is there for
    checking the junctions of diodes and other semiconductors. It's a variant
    of the ohmmeter function, in that it applies small voltage to the probes
    so you can measure resistance. But it is arranged so it can better check
    those semiconductor junctions. Put a diode across the leads, and set
    the function switch to that function, and in one direction you will
    get a maximum reading (ie the same as if nothing is connected to the leads)
    and in the other direction you will get a low reading. That's for a good
    diode. A shorted one will show a low reading in both directions, an open
    diode will show a high reading in either direction. The reading you see
    if it's a good diode will let you determine the type of diode (ie germanium
    which you aren't likely to come across much, silicon and schottky, since
    each have a different voltage drop). Since a transistor is two junctions,
    you can use the function to check the junctions of those, though you'll have
    to check the base-emitter junction, and then the base-collector junction.

    The "HFE" is for measuring transistor gain. There should be a socket to
    plug the transistor into for doing the measuring. I've had a meter with
    the function for almost ten years, and other than playing with the function
    at the beginning, have never used it.

  7. I'd say "unfortunately" for you!
    You learn a *lot* more when something doesn't work and you have to
    debug it!

    There are on-line tutorials like these:

    Books abound as well, visit your local library or uni library.

    Dave :)
  8. Jasen Betts

    Jasen Betts Guest

    Yeah there was a warning on the (lacking) instructions about measuring that
    That's for testing transistors and seeing how well they work, for that use
    use the small round socket labeled E C B E PNP NPN etc

    the ->|- symbol the diode symbol it'll measure the forwards voltage drop.
    it'll give you a reading og 0.6 (approx) for a silicon diode and abour 0.2
    for a germanium diode.

    always remember to turn it off bacase the cheap DSE multimeters don't power
    down automatically and so will run the battery down if left on overnight a
    few times.

    get a few spare fuuses for it cause it's pretty easy to blow them if you mis-
    use it on the mA scale. (there is room inside the case to store them if you
    wrap them in plastic)

  9. Jasen Betts

    Jasen Betts Guest

    That was your first kit, and it works? well done!

    (I'm assuming it was either the Jaycar or the Altronics version of the Aug
    2000 Silicon Chip mag. Theremin kit) and not a classic theremin with vlaves
    and all.

  10. kell

    kell Guest

    You got some good answers about how to use your meter. Beyond that, I
    would suggest you look up Ohm's law and the other laws that relate
    current, voltage, resistance, and power. You will understand much
    better what those measurements you get with your meter really mean.
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