Re: DC Coil breakthrough!

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

Original poster: "G by way of Terry Fritz <twftesla-at-qwest-dot-net>" <bog-at-cinci.rr-dot-com>

Hi Steve,

>1) Charging reactor = 9.8 Henry
>  BPS    DCkV    DCmA    DC watts    AC VA
>  800    8.5    115        978        1419
>1000    7.5    130        975        1375
>
>One obvious thing is that my MOT DC supply is not very efficient.  Assuming
>unity power factor, the efficiency is only around 70%.  I have no 
>idea what the
>real PF is.  Has anyone tried PFCs with a MOT DC supply to see if the VAs can
>be reduced some?

I have come into over 10 kvars of industrial pfc caps, and I will try 
them for sure whenever my geek caps arrive and I can get the spdt 
setup rolling.

>  2) I tried adding another charging reactor MOT in series for a total of 22
>Henry:
>
>BPS    DCkV    DCmA    DC watts    AC VA
>  800    8.5    112        952        1370
>1000    7.2    130        936        1309
>
>Roughly the same performance - my measurements are not very precise.
>
>3) Last case - two MOTs in parallel for a charging reactance of about 5.4
>Henry:
>
>BPS    DCkV    DCmA    DC watts    AC VA
>  800    8.5    105        893        1295
>1000    8.0    130        1040       1451
>
>As a comparison, my SPDT setup took about 1,300 DC watts to do a 48 inch spark
>length.  Two gaps are obviously less efficient than one.
>
>So it appears the charging reactance is not very critical, and probably most
>any MOT will do.  After running the above experiments over a period of an hour
>or so, the charging reactor was only slightly warm.

This looks great. Good work, I'm actually glad the geek group has a 
backlog of cap orders, now that you have found a better way. One 
question- did you leave the secondary winding on the core and short 
the primary winding, or did you remove it entirely from the core?

Also, did you see a streamer length increase, or just the VA drop?

Regards,
Gregory

>
>As I said above, my current power supply uses dual MOTS driving dual triplers.
>Keeping in mind that the tank cap charges to about twice the DC 
>supply voltage,
>triplers are overkill unless one has a tank cap rated for 30 KV or more.  A
>more efficient and simpler power supply design would be two MOTs in series
>driving a voltage doubler circuit, which would put out about 11 KV unloaded.
>That was my original setup - guess I will go back to it.  With a chargng
>reactor setup, there is no need for my big (lethal!) filter cap--4 microwave
>oven caps in series should do the job.
>
>So the good news is that one can make a well performing DC powered TC using
>nothing more than a bunch of salvaged microwave ovens.  The only tricky thing
>is to have a RSG with a BPS of over 600.  Or, hopefully much better, use a
>triggered gap driven by a variable pulse rate drive circuit.  Comments
>welcomed, especially from others who try this.
>
>--Steve