Re: Capacitor Applications

[Mark Sylvester <msylvest@XNET.IT>]

At 14:17 15/01/01 -0800, Leigh Palmer wrote:
> >   --) The ignition-spark system for a car has an important capacitor in it.
>
> Oh? It had one in the old days which was a spark suppressor, used
> solely to extend the life of the breaker points by preventing a
> high current spark when the current through an inductor (the spark
> coil primary) was interrupted.



Was that its sole function, or did it also increase the rate at which the
current dropped to zero, thereby boosting the ignition voltage? I have a
model ignition coil in the lab, with a removable "condenser". Removing it
makes the induced spark across the high voltage coil more or less disappear.




>  That capacitor was usually called a
> "condenser", by the way. In a modern* electronic ignition system
> the breaker points operate at low voltage and the switching is
> done by a solid state device. The lifetime of the points exceeds
> that of most automobiles, and a condenser is not needed.
>
> Leigh
>
> * Few if any of our students are old enough to remember any other
> kind of ignition system, and a fraction now approaching 0% work on
> their engines.





Well, it's not so surprising. Under the bonnet of my car it looks more like
inside a TV set than a car!

Mark


Mark Sylvester
UWCAd
Duino Trieste Italy