Re: ~Microsim~

At 06:58 PM 8/5/99 -0400, you wrote:
>I read your "Modeled and Actual Voltage and Current Waveforms within a Tesla 
>Coil" paper....read it several times actually. I was particularly impressed 
>with your measurement system, looks like you've got some nice equipment 

Thanks!  A lot of work went into that paper...

>I do have a few questions to run by you though, mostly about the spice 
>schematic of your TC. There is a resistor labeled Rac with a 0.5 value right 
>after the ac input, what is the purpose of this resistor, and is it standard 
>to all TCs or must it be measured for each? 

The AC source is perfect (too perfect), so I add a small resistance to
simulate AC line droop when a lot of current is drawn.  These days I use
0.2 ohms which is about the resistance of 50 feet of 12 gauge house wire.
This is not critical at all.  I find that my AC will drop a few volts at
full current draw.  Since I like to measure things so much, I wanted to
account for this.

>Next you have two resistors 
>labeled Rni1 and Rni2 with 0.12 values, I have the same questions about 
>these, what is their purpose and are they standard or measured? 

That is the DC resistance of the primary winding of my 15kV/60mA neon.  I
try to put such resistance in since they draw power and the system may ring
unrealistically without such losses in the model.

>I assume they 
>have something to do with the resistance through the primary of the NST but 
>I'm not sure. Speaking of the NST I noticed it's a 15/60, I power my unit 
>with a 7.5/30 what would I need to modify from your schematic to get the 
>correct values for mine? 

Find the DC resistance of the primary and secondary windings and replace
the values I have in the model with your measurements.  Measure each leg of
the secondary to ground.  

Then reduce the secondary inductance to 1/4 the values I have.  This will
change the output voltage to 7.5kV.

Then place a short on the output of the neon and adjust the coupling by
trial and error until the short circuit current in the secondary matches
you transformer.

Now you should be all set.  One could readjust the primary inductance but
that can get pretty involved and the above should work fine.  That involves
measuring the open load current draw to find the primary inductance.

>And just how did you figure out the coupling, L1, 
>and L2 values for your neon? Overall Tesla Coil simulation looks to be very 
>promising, perhaps it will shorten the trial and error part of TCing by an 
>hour or two *lol*

L1 is found from the open load AC current draw.  The open load AC current
is limited by the primary inductance so the values are adjusted to match a
measured value.  L2 = L1 x (V2 / V1)^2



BTW - It has been a long time since I did this part of the model and I am
writing this from memory.  So, if something seems "all screwed up"...

>Left, left, I hadda good brain but it left...