So this is what they mean by "non-sinusoidal waveform".

Discussion in 'General Electronics Chat' started by mbohuntr, Jun 3, 2012.

  1. mbohuntr

    Thread Starter Active Member

    Apr 6, 2009
    We bought an inverter to power some toys at camp, and when we opened the box, the directions warned about some applications not liking the inverter. Naturally I had to put a scope on it for a look see. EEwwwww. :eek: Now I guess I'll have to take a look at the generators...:rolleyes:
  2. wmodavis

    Well-Known Member

    Oct 23, 2010
    Yup! Doesn't look sinusoidal to me.
  3. crutschow


    Mar 14, 2008
    It costs more to generate a power sinewave efficiently so most inexpensive inverters use a switched step type of drive with no output filter. In your inverter it's a three step design, stopping at 0V between the plus and minus excursions. More expensive inverters use more steps and/or output filtering to more closely approximate a sinewave.
  4. ErnieM

    AAC Fanatic!

    Apr 24, 2011
    Believe it or not that wave puts most of it's energy out at the fundamental line frequency.

    I've heard several anecdotal stories of devices such as microwave ovens failing almost immediately after being given such power.
  5. mbohuntr

    Thread Starter Active Member

    Apr 6, 2009
    I'm thinking my flourescent lights didn't like the taste either.:( I'm going to research the generators outputs as some of the loads could possibly be shaded pole, like my pellet stove motors. :eek: Probably not as bad as the inverter, but worth a look.
  6. anotheruser1


    Dec 6, 2011
    A question to fit this thread.. Are the inverters in an uninterruptable power supply ( say an APC 750) a true or modified sine wave? They look 100 times more advanced just by looking at one.
  7. Brownout

    Well-Known Member

    Jan 10, 2012
    It's called a "modified sine wave" inverter. Almost all economy inverters make this wave. They are good for lights and other resistive loads, but not for much of anything else. My inverter fails to operate my little compressor, but does work well when I connect a fan. Go figure.