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From: email@example.com (N. Thornton)
Subject: Re: 12V Fluorescent lamp driver
Date: 1 Nov 2002 05:46:34 -0800
NNTP-Posting-Date: 1 Nov 2002 13:46:35 GMT
"R. Lewis" wrote in message news:...
> "N. Thornton" wrote
> > firstname.lastname@example.org (Dave H) wrote in message
> > > I'm planning to build a circuit to drive a Compact fluorescent lamp
> > > from a 12v car battery for use in a garden shed. The circuit wants to
> > > be as cheap/reliable as poss and preferably use off the shelf
> > > components.
> > >
> > > I was thinking along the lines of a simple oscillator (running at
> > > roughly 50hz) driving something like a 2N3055 connected to the
> > > secondary of a mains transformer.
> > >
> > > Is there a better way?
> > Sounds perfectly effective. Yes there are ways better in some
> > respects, but what is wanted is simplicity, ease of building and low
> > cost. Your solution fits the bill.
> > I would be temted to use a higher frequency, maybe a few hundred Hz.
> > And your invertor will have no regulation, and a 12v batt swings ovre
> > a wide V range. So I would add tap switching to select the nearrest
> > voltage - otherwise your V will be miles out at times.
> If you use 'a few hundred Hz' what ballast can be used?
> Discharge tubes, such as fluorescent tubes, have a negative resistance and
> must be 'ballasted' in some way.
> Typically from low voltage DC, fluo' tubes are powered by a Hartley or Royer
> type inverter at frequencies in the tens of kHz.
> The output of the inverter (transformer) , although it has a high(ish)
> impedance, generally requires ballasting - which is normally achieved with a
> Unless you are familiar with such things they can be tricky.
> If you go down the mains frequency/volts route be aware that some, but not
> all, mains ballasts ('chokes') are far from happy with square waves.
> In the interest of efficiency you may want to power factor correct your
> mains ballast set-up.
Dave is running a CFL, not a FL. They should run just as well off
300Hz as 50Hz.
But I think the suggestion to get a 12v CFL has to be the most
sensible. Personally I would be more into running mains power to the
shed, that would be far more useful.
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