fluorescent ballast Re: transformers

From:  Eric Davidson [SMTP:edavidson-at-icva.gov]
Sent:  Thursday, June 18, 1998 9:36 AM
To:  Tesla List
Subject:  Re: fluorescent ballast Re: transformers

Bill et al:

There are several different types of ballasts used for fluorescent
lamps. The simple reactor types are used with a starter on small lamps,
up to 24 inch.  Totally useless for TC power supplies.  The ballasts for
40 watt rapid start lamps have a no load voltage of about 350 volts
across the lamp. This drops significantly after the lamp lights.  These
ballasts also provide about 3.5 volts to heat the filament. These
ballasts are no good for TC use IMO.  The ballasts used for the
'slimline' type 8 ft. lamps are the only ones that would even be close
to suitable for TC use.  The put out around 700 volts (listed on
ballast) and to my knowledge the secondary is isolated from the case.  I
could be wrong on that so test it.  This would theoretically open the
possibility of putting 10 or so of them in series for some decent
voltage.  The big problem will be insulation, or lack of it. I would
never try putting 10 in series.  Maybe some of the others on the list
who enjoy unpotting and cleaning NSTs could give some insight into
unpotting and rebuilding (fluorescent lamp ballasts) FLBs. Then maybe
they could be immersed in oil and the insulation problem may go away. 
As for the ballasts for HO (high output) lamps, dont bother, they are
way too expensive, you may as well buy a NST.  Hope this helps. 

Tesla List wrote:
> ----------
> From:  Bill Noble [SMTP:william_b_noble-at-email.msn-dot-com]
> Sent:  Tuesday, June 16, 1998 1:40 AM
> To:  Tesla List
> Subject:  fluorescent ballast Re: transformers
> the flourescent ballasts provide a HV kick to start the plasma discharge,
> and they provide current limiting - inside is an inductor and a capacitor or
> two.   off the top of my head, running voltage on a fluorescent is on the
> order of 60 volts, start voltage on an 8 ft tube on the order of 900 V - I
> don't have my fluorescent light handbook handy any more.  On the older type
> ballasts that work with a starter, they are an inductor only, when the
> starter is cold, it is a short, placing the filaments in series across the
> inductor - you get about 12 V to heat the filaments.  Then the starter heats
> up and goes open circuit and the voltage spike ignites the tube.
> Probably not of great value for generating tesla coil voltages, but an old
> starter may be useful as part of a inductive element in a power line filter,
> if your current is really low - like 100 to 500 ma.

Have a good day!
Eric Davidson