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Re: Newbie Questions
Original poster: "Jonathan Peakall by way of Terry Fritz <teslalist-at-qwest-dot-net>" <jpeakall-at-madlabs.info>
In flyback drivers I have had good luck with the HV3055 sold by All
Electronics. MUCH more durable than the regular 2N3055. Heavier case, higher
voltage rating. I haven't used them on an IC, but have yet to blow one on a
flyback. Unless I was doing something really silly ;-P
----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
Sent: Friday, April 25, 2003 6:39 AM
Subject: Re: Newbie Questions
> Original poster: "Stephen Conner by way of Terry Fritz
> At 20:58 24/04/03 -0600, you wrote:
> >Original poster: "by way of Terry Fritz <teslalist-at-qwest-dot-net>"
> >Stephen Conner wrote:
> > > The base bias resistor is probably too big even for 12 volts.
> > > ...... That would mean using a 20 ohm resistor, ....So you ought to
> > > extra emitter follower in.
> >Stephen....your reply helped a lot. Added an emitter follower, (still
> >the 100 ohm
> >base resistor) and the spark doubled in length to 1/2 inch. Changed the
> >base bias
> >resistor to 22 ohms and gained another 1/4 inch, for a total of 3/4 inch.
> >The spark was
> >screaming :-) Then it all stopped :-( Guess the NPN transistor smoked.
> >Didn't have the
> >time to measure current, before it fried.
> >Need to buy more transistors. LOL
> Don't buy 2N3055s, they suck for this application. You're trying to
> generate a hi-voltage spike by turning the transistor off suddenly, but
> 2N3055 can't take more than about 70-100V before it dies. A specialized
> high-voltage switching transistor like the BU208D ought to work much
> better. Note: The BU208D is easy to get over here in Europe but might be
> rare in the US. Maybe someone else could suggest an equivalent?
> You can find a couple more ignition coil drivers at
> http://www.powerlabs-dot-org/ My favourite one runs straight off the 120V line
> and uses a SCR instead of a transistor. It gives pretty impressive results
> when driving 2 ignition coils, but could be a bit dangerous.
> Steve C.