Re: DRSSTC Additional questions

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Terry Fritz <vardin@xxxxxxxxxxxxxxxxxxxxxxx>

Hi Skip,

Even though the output is pretty even with a miss-tuned primary, the 
primary current may be much higher.  It is like the system resonates 
the primary current up until a certain power to the secondary is 
obtained.  The primary current will be least when the tuning is correct.

If the primary was so miss-tuned that there was no transfer to the 
secondary, the primary current and voltage would just rise 
un-restrained until something blows up.  So tuning might now be a 
matter of finding the least primary current point per given output.

Cheers,

        Terry


At 09:13 PM 9/22/2005, you wrote:
> Hi all
> Ok, the primary feedback using Steve's two coil system works great. 
> New questions
>
> 1. The tuning of the system is much broader than any TC that I have 
> ever built. There is little difference in spark length when adding 
> or subtracting two or three turns to the primary. Is this typical of 
> DRSSTCs? Per JAVATC the coupling is between .18 and .2. The resonant 
> frequency seems to hold pretty steady at 285khz regardless of the 
> turns in the primary.
>
> 2. Doubling the tank cap size definitely lowers the resonant 
> frequency and the input current goes up dramatically but there is 
> little effect on the spark length and the primary turns still seem 
> to have minor effect on the spark length up to a certain point. Are 
> others seeing the very broad tuning that I seem to be getting.
>
> So far I am only inputting 60vac to the full wave dc bridge and 
> spark length is approaching 12". The secondary is only 18.5" long. I 
> am leery of increasing the input voltage until I understand this 
> apparent broad tuning.
> Any comments would be appreciated. Thanks Steve and everyone for the 
> feedback help.
> Skip