[HomeBrew] Inverter

[bhat srikanth]

Hello,

In India, we use 12vDC to 230vAC square wave inverters
during power outages, and run almost anything at home
using it. Sine wave inverters are expensive and are
generally used only in commercial applications.. The
square wave output's sharp edges are rounded off using
a 2.0 or 2.2 UF high voltage AC capacitor in parallel
to the output - these capacitors are like the one used
in cieling fan motors (used for phase shifting in the
motor)..

It works pretty OK with almost all kinds of loads.
Though fans and other inductive loads tend to make a
bit of extra noise, its live-able.. 

For TVs and other devices that generally use SMPS the
square wave will hardly matter as it first rectifies
it at the input. If the spikes are very very large,
then maybe the rectifier may suffer - but thats seldom
the case with the capacitor included. 

The capacitor will no doubt cause a bit of extra
standby current.. but its worth it.

73
de Sri, vu2sbj
Manipal, India.


--- n_griggs at bellsouth.net wrote:

> ** Please do NOT cross-post messages when posting to
> HOMEBREW **
> 
> Most cell phone chargers and laptop supplies are
> switching supplies like in a desktop computer
> supply.  No input transformer - the input is
> rectified and sometimes doubled or tripled then sent
>  to a switching circuit and transformer.  They don't
> care if the input is sine, triangle or square wave
> since there is no input transformer.
> 
> > 
> > From: john.brewer at us.schneider-electric.com
> > Date: 2005/12/06 Tue AM 09:02:42 EST
> > To: homebrew at mailman.qth.net
> > Subject: [HomeBrew] Inverter
> > 
> > ** Please do NOT cross-post messages when posting
> to HOMEBREW **
> > 
> > 
> > Sorry your TV died!  I would expect that the
> primary of power supply transformer would act much
> > like the filter you mention you're looking for.
> Would be interesting to look at the secondary
> > and see if there's any transients propagated
> through the transformer under load.  I've used a
> > number of these things to power low power
> equipment (laptop, cell phone chargers, etc) with no
> > problems.  I know the unloaded output of these
> things looks pretty awful!
> > 
> > John
> > 
> > _______________________________________________
> > HomeBrew mailing list
> > HomeBrew at mailman.qth.net
> > http://mailman.qth.net/mailman/listinfo/homebrew
> > 
> 
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