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Re: 555 2n3055 was:The incredible inedible ignition coil

Original poster: "Jan Florian Wagner by way of Terry Fritz <twftesla-at-uswest-dot-net>" <jwagner-at-cc.hut.fi>


> What I like to do to put those 2n3055s into use is use a 555 to drive a
> 2n2222 and have it switch a current limited amount of the source into the
> base of a 2n3055 on a seperate supply having a common ground.

You can also use a totem-pole drive, with a NPN like 2n2222 and PNP like
BC640 (if I remember right) transistor. This allows fast switching,
espacially if you use a mosfet. You can see how this looks like

 (sorry for ugly hand drawing... :o)

I've run this without a series transistor base resistor, as the PWM ic is
current limited. A 555 timer may require some 10 ohms. 

Well, that schematic is for mosfet driving, and for the lower section of a
half bridge, meaning you could actually leave out the expensive D1
Schottky and D2 fast recovery diodes for typical flyback use.

I've the whole schematic at
but it still needs a bit of cleaning up, mainly the schematics. Also the
audio sense/react section needs improvement so that it actually will work 
;o) with electret mics. But anyway...


 high voltage at http://www.hut.fi/~jwagner/tesla