Re: Tube coil, level shifter madness

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

Original poster: "by way of Terry Fritz <twftesla-at-uswest-dot-net>" <FutureT-at-aol-dot-com>

In a message dated 1/1/01 11:14:29 AM Eastern Standard Time, tesla-at-pupman-dot-com 
writes:

Dave,

I tried both 0.97uF and almost double that, with no change.  I also
tried without the modulator which then gave results similar to the
3600V winding, without level shift.  I agree that I have to try adjusting
the modulator, or use the 555 based unit, which I've found in the
past works better with the level shift than the TTL.  This was just a
quick test I did.  I'm a strong advocate of the level shifted design.  
The rapid pulse train with rests in between is a good idea and is 
another thing I've wanted to try for a long time.  Many things to do.
I take my time lately, and it takes forever to finish a project.

Thanks,
John Freau
--

> John 
>  
>  What size level shift capacitor are you using?  If you use the 50% power 
>  rule I suggested earlier, with 2.8kV peak input, here is an equation to
>  calculate 
>  proper cap sizing based on 50% peak energy contribution from transformer 
>  and 50% peak energy contribution from capacitor... 
>  
>  CLS = PIN / (2 * FPWR * (VPK)^2))*1000000 
>  
>  Where: 
>  CLS = Level Shift Capacitor (uF) 
>  PIN = Average Power Input to VTTC oscillator 
>  FPWR = Utility Line Frequency 
>  VPK = Peak input voltage to VTTC oscillator 
>  
>  This equation is a simplified output of earlier discussion posted 
8/22/2000 
>  and is generally applicable to all VTTC applications.  Capacitor sizing 
can 
>  vary +/-10% of calculated with little effect on output. 
>  
>  Realistic equation for Vpk is 
>  VPK = VRMS * 1.414 - VFWD diode drop 
>  
>  VFWD  ranges from 10-12 volts based on number of series diodes in your 
>  level shift diode. 
>  
>  Based on above, your level shift capacitor should be around 1uF (1.17uF to 
>  0.96uF). 
>