Re: bridged ignition coils

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Jim Lux by way of Terry Fritz <teslalist-at-qwest-dot-net>" <jimlux-at-earthlink-dot-net>

At 10:51 AM 5/2/2003 -0600, you wrote:
>Original poster: "Jolyon Vater Cox by way of Terry Fritz 
><teslalist-at-qwest-dot-net>" <jolyon-at-vatercox.freeserve.co.uk>
>
> > Original poster: "Stephen Conner by way of Terry Fritz
><teslalist-at-qwest-dot-net>" <steve-at-scopeboy-dot-com>
> >
> > At 07:34 01/05/03 -0600, you wrote:
> > >Original poster: "Jolyon Vater Cox by way of Terry Fritz
> > ><teslalist-at-qwest-dot-net>" <jolyon-at-vatercox.freeserve.co.uk>
> > >
> >
> > I don't know about the drive circuit though. You need hundreds of volts
> > going into the primary.
>
>Aren't the hundreds of volts induced in the primary as a result of the rapid
>interruption of the primary current?
>Therefore, if the rate of change in the primary current was sufficiently
>fast wouldn't the above requirement be fulfilled, and  wouldn't a bipolar
>square wave,with a fast rise and fall times, be sufficient to do this?

That's one way to get the voltage (if you're running off 12V).. use the L 
di/dt.

The other way is just to drive it with a few hundred volts directly. When 
all is said and done, an ignition coil is just a transformer with a lot of 
inductance. Nothing special.