[HomeBrew] Smoothing a square wave

[n_griggs at bellsouth.net]

You should have no problems using this with your computer since almost all computer supplies are switching supplies.  They rectify the incoming ac and filter it.  The first transformer that the power 'sees' is the step down transformer for the rectified line voltage in.  Most also use voltage doubling when in 110 vac mode.
> 
> From: n1khb at aol.com
> Date: 2006/05/04 Thu PM 01:19:31 EDT
> To: JimMiller at STL-OnLine.Net,  HomeBrew at mailman.qth.net
> Subject: Re: [HomeBrew] Smoothing a square wave
> 
> ** 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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