STRUDWICK.FAMILY wrote:
> Barry
>
> I will jump in if I may, sorry Ron if I am stealing your thunder,
> inverters from 12 volts to mains voltage have to use a devise called a
> step up transformer. These devices need to be fed with an alternating
> current(ac)  at a frequency of 50 cycles per second. This is the same
> frequency as the mains and can be used power your TV and other
> equipment.  The problem is how to make this ac from the direct current
> of your battery. Your house hold supply this is a nice sine wave with
> no jaggedy bits on it. The way the ac is made in most inverters is to
> produce square waves and put  these together to produce a "sort of
> sine wave" which is full of jaggedy bits. These unwanted bits can
> cause problems depending on the design and type of equipment you are
> using. The more you pay for the inverter in the first place the
> nearer the output wave form is to that of the house hold mains supply.
>

Well said Paul.  In my view the best solution is always buy TVs that are 
designed to run on a 12V car/caravan/lorry/boat supply.  A source I have 
used in the past has been http://www.roadpro.co.uk.  Our current boat TV is 
just great - good colour, very stable picture and it will usually work down 
to about 10 voles or so - then you start getting some noise on audio when 
the picture is bright (time to change batteries).  I will change it in a 
couple of years as it's analogue only and analogue transmissions start being 
switched off *next year* (but not where the boat is!)

Ron Jones
Process Safety & Development Specialist
Don't repeat history, unreported chemical lab/plant near misses at 
http://www.crhf.org.uk
Only two things are certain: The universe and human stupidity; and I'm not 
certain about the universe. ~ Albert Einstein. 


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