[HomeBrew] Smoothing a square wave

[Doug Laidlaw]

In addition, the square wave is probably rated peak.  With the corners rounded 
off, its RMS value would then be too low.

Doug VK3KDI.

On Fri, 5 May 2006 03:19 am, n1khb at aol.com wrote:
> ** Please do NOT cross-post messages when posting to HOMEBREW **
>
> Inverters and the equipment that they run don't always get along very
> well. which is why I attempt to buy things like tv's that are
> anticipated to run in such situations already equipped (designed in) to
> run on 12v dc to begin with. Inverters just aren't going to do it all
> even if they are of the modified sine wave type which are really just a
> variant of a square wave according to the one that I looked at on the
> oscilloscope.
>
> Joe N1KHB
>
>
>
> -----Original Message-----
> From: Jim Miller <JimMiller at STL-OnLine.Net>
> To: Homebrew, Reflector <HomeBrew at mailman.qth.net>
> Sent: Thu, 4 May 2006 09:43:31 -0500
> Subject: [HomeBrew] Smoothing a square wave
>
> ** Please do NOT cross-post messages when posting to HOMEBREW **
>
> I have an inverter that I blame for blowing up a 9 inch color TV that I
> use at
> my station and wanted it also to run on 12v as battery backup as my
> station
> does.  I scoped the output and it is a two-step (two positive and two
> negative)
> square wave output.  I had also  intended to connect my computer to it
> but
> haven't tried that because the TV blew up.  Does anyone know what the
> output of
> these UPS systems look like?
>
> At 60 Hz, it would take a huge inductor to "round" the corners of the
> wave but I
> have a very large pole pig sitting here and wondered if one side could
> be used
> simply as an inductor or wire the two sides in series, maybe put a load
> on the
> unused side or something.  High side or low side?  How much of a load?
> Use a
> cap instead of a load?  OK, dumb idea.
>
> For a small TV only maybe a small LONG "extension" cord wound in a
> small coil
> would help smooth the square wave?
>
> 1. It says the max current is 1 amp.
> 2. 20 gauge (too much voltage drop?  I don't have the numbers to
> calculate it.
> 3. 100-200 feet?  Not long enough to create enough inductance?
>
> Opinions please, I am not a design engineer, just trying to get a small
> TV to
> safely run on an inverter or was it coincidence that it quit within
> minutes of
> plugging it into the inverter?
>
> Thanks es 73 de Jim KG0KP
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