[Prev][Next][Index][Thread]
Re: Not enough pimary inductance?
In a message dated 11/17/98 8:07:22 PM Pacific Standard Time, tesla-at-pupman-dot-com
writes:
<<
I have a small coil here which has a "roller coil" in series with the
primary for tuning. I don't have the numbers handy at the moment, but
it has a total inductance range of from close to zero to about 1/3 of
the primary inductance. I can tune the primary using this arrangement
(coil is tuned through long strings wrapped around a pulley) and find I
don't seem to lose much in the way of streamer length by this method as
contrasted to having all of the primary inductance at the base of the
coil. That is obviously better, but for a quick start I'd wind any old
tapped coil, play with it until I got the tuning right, and then build a
new primary of the appropriate inductance, plus a few turns for safety.
The primary tuning has a large effect when the input voltage to the
transformer is so low that the spark rate is only a few a second, but at
full input and spark rate it has almost no effect at all. I believe
this is because the loaded Q of the secondary is quite low under this
condition.
Ed
>>
It is interesting to know that you have used a separate coil in series with
the primary for tuning. Didn't Tesla also do this? I think it is mentioned
in his notes.
The last part, I agree with you. I have done a lot of work on tuning on my
system. At low power, I can tell the difference between one turn and even one
half turn. At high power, it is different. The tap sensitivity is just not
the same at say 8 kva compared to 1 kva. I know the Q of my secondary should
be high. I used all the right materials, good construction methods, etc.
These details may be way more important for small, low power systems than the
high power variety.
Ed Sonderman