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Re: 250watt solid-state flybacks? (fwd)



On Fri, 15 Oct 1999 11:41:12 -0600 Tesla List <tesla-at-pupman-dot-com> writes:
> Original Poster: "davidhosking" <davidhosking-at-bigpond-dot-com> 
> 
<snip>
> I guess the Helmet mounted secondary will need fairly thin wire to 
> get a
> reasonable number
> of turns.
> Anyone had experience with making secondary coils say about 40mm 
> diamx100mm
> high?

David,

try http://privat.schlund.de/s/skluge/sub4.htm

Stefan something or other built a coil he refers to as the "vitamini",
with a secondary measuring 1.14" dia and a 5.14" winding length. Using a
10cm mean dia toroid, he produced 20cm (10KV 18ma OBIT supply)streamers,
but using a second secondary with a connection to the first. 11.5cm arcs
were produced with the single secondary.

Grayson Dietrich

> Kind regards,
> David Hosking
> Pharmacist,Amateur scientist, Pyrotechnician & Tesla Coiler.
> 
>  "Be very careful what you put into your brain
>   because you will never get it out!"
> 
> ----- Original Message -----
> From: Tesla List <tesla-at-pupman-dot-com>
> To: <tesla-at-pupman-dot-com>
> Sent: Thursday, October 14, 1999 10:14 AM
> Subject: Re: 250watt solid-state flybacks? (fwd)
> 
> 
> > Original Poster: Tesla List <mod1-at-pupman-dot-com>
> >
> >
> >
> > ---------- Forwarded message ----------
> > Date: Wed, 13 Oct 1999 08:51:43 EDT
> > From: Bobbaust-at-aol-dot-com
> > To: tesla-at-pupman-dot-com
> > Subject: Re: 250watt solid-state flybacks? (fwd)
> >
> >
> > > Subject: Re: 250watt solid-state flybacks? (fwd)
> > >
> > >  Hi David,
> > >               ditch the 2 lead acids for a start.  The power you 
> can put
> > into
> > >
> > >  most flybacks at 24V would be more like 50W or 100 if you were 
> lucky.
> I
> > >  suspect I was the guy who said you can get 250W into a flyback. 
>  For
> this
> > I
> > >  used a 70V supply and put about 4A in but the FETs burnt at 
> least
> 30-40W
> > of
> > >  that so cal it 250W.
> > >  The basic system is fairly simple, a square wave oscillator, a 
> a fet
> > driver
> > >  chip and a large FET or bipolar.  It is easier to use fets as 
> they draw
> a
> > > lot
> > >  less base current and make life easier for the driver.  If you 
> use the
> 555
> > > as
> > >  your oscillator you can drive it straight into the FET as the 
> 555 can
> > >  sink/source 500ma, remember to put a snubber network in tp 
> protect the
> > 555,
> > >  this isn't really necessary but it easier to take little 
> peracutions
> that
> > >  cost almost nothing than keep blowing chips.
> > >  I would question whether you need that much drive power as all 
> that the
> > >  higher power seems to do is heat up the flyback and make the 
> sparks
> more
> > >  intense.  I have tried up to 2kW into a flyback and all it did 
> was
> shoot a
> > >  huge arc then blow itself to bits leaving little more than a 
> scorched
> > core.
> > >
> > >  For your application I would say that you want about a 100W or 
> so.
> > > Therefore
> > >  I would have thought you could get away with about 40-50V drive
> depending
> > on
> > >
> > >  your flyback.
> > >
> > >  Have (Head Mounted) Fun
> > >  Nick Field
> > >
> > Sounds like Nick thinks you need more voltage input than your 
> batteries
> > alone.  Some options:
> > 1) use 3 or 4 smaller lead acid batteries in series for 36-48 VDC 
> as a
> > source.
> > 2) use the 12 V battery to feed a canniballized car stereo amp, 
> they
> usually
> > have internal inverters that convert 12vdc to around plus & minus 
> 20 to 30
> > vdc supplies for a total of 40 to 60 vdc.
> > 3) use the 12v battery to feed an inexpensive auto inverter.  You 
> can get
> > these for $30 - $40 rated at 100 to 140 watts.  They have 
> inverters and
> > generate a 170-180 vdc supply.  They also have high-V high-speed 
> switching
> > transistors (probably mosfets) to produce a nice square wave for 
> the
> > "modified sine wave" output they all put out
> >
> > If you get someting working let us know, this sound like something 
> I would
> > build (and wear).
> >
> > Bob Baust, newbie
> >
> 
> 

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