Re: Addendum-DC Tesla

Tesla List wrote:

> >> Sure it's rectification due to dissimilar electrodes.  You can
>                                   ^^^^^^^^^^^^^^^^^^^^^
> >> charge a capacitor with DC from a spark coil if you use such
> >> electodes, for example a disk and a needle, and play with spark
>                             ^^^^^^^^^^^^^^^^^
> >> 
> Sounds more like dissimilar *shapes* to me. ;)

> Dan Kline  <ntesla1-at-vm.sc.edu>

Actually, the output of a Tesla coil (before the arc) is pretty close 
to a perfect sine wave due to the high Q of a good coil.  However, 
discharge is a very short (steep dV/dt) phenomena- thats why you get 
harmonics up into VHF for short range.  

Because discharge is so short compared to the period of the sine wave, 
its likely that any particular discharge into a cap will end up 
charging over only one half of a cycle.  In fact, it would be quite a 
coincidence if the arc discharge occurred equally over the neg and pos 
parts of the cycle, with a net of 0 DC volts charge. 

If you doubt this, try connecting a 0.1uF -at-250v cap accross the 120V 
line and then putting your fingers across the cap.  Surely its easy to 
get dc out of ac with a spark discharge.  If it works at 120v, I'm 
sure it will work at 120kv.