Re: DC Resonance Charging Advice Sought

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

Original poster: "Bert Hickman by way of Terry Fritz <teslalist-at-qwest-dot-net>" <bert.hickman-at-aquila-dot-net>

Hi Dave,

The cutoff frequency of the RC filter is really not very critical since its 
purpose is to absorb transients in the high MHz region - a filter with a 
cutoff frequency in the range of say 50 - 200 kHz should be quite adequate. 
The high DC voltage rating of the inductor is excellent.

BTW, does the reactor's faceplate state the max DC operating current and DC 
resistance? These are nice to know in order to insure that you don't 
saturate the reactor, and to predict expected output voltage in operation. 
Assuming your reactor does not saturate, peak reactor current will be about 
~190-200 mA and average current ~120-130 mA depending upon reactor winding 
resistance. The max breakrate (assuming Rreactor < 7 kOhms) is a shade 
above 500 BPS. Vout and charging efficiency will be a function of your 
reactor's DC resistance as follows:

Rreactor        Vout            Efficiency
(Ohms)          (Volts)         (%)
500             12397           99%
1000            12620           97.5%
2000            12009           95%
5000            10341           87.6%
10000           8025            75%

Good luck and best regards,

-- Bert --
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Tesla list wrote:
>Original poster: "Dave Kyle by way of Terry Fritz <teslalist-at-qwest-dot-net>" 
><dave-at-kyleusa-dot-com>
>Interesting! I do not know if it matters but the inductor is rated to
>15KVDC. What would you suggest for the cut off frequency for the low pass
>filter?
>Dave
>=========================================
>Dave Kyle
>Austin, TX USA
>Email: dave-at-kyleusa-dot-com
>
>-----Original Message-----
>From: Tesla list [mailto:tesla-at-pupman-dot-com]
>Sent: Tuesday, August 12, 2003 9:53 AM
>To: tesla-at-pupman-dot-com
>Subject: Re: DC Resonance Charging Advice Sought
>Original poster: "Bert Hickman by way of Terry Fritz <teslalist-at-qwest-dot-net>"
><bert.hickman-at-aquila-dot-net>
>Tesla list wrote:
>  >Original poster: "Dave Kyle by way of Terry Fritz <teslalist-at-qwest-dot-net>"
>  ><dave-at-kyleusa-dot-com>
>  >Thank you for your responses! Please see my comments in line
><SNIP>
>  >This leads to the question, on which side of the inductor the de-Qing diode
>  >should be placed? Based on Richie's information and Steve's design I put it
>  >on the power supply side but I have seen other references with the de-Qing
>  >diode on the tank side. Any thoughts?
>I suspect it doesn't really matter very much. The sudden voltage drop when
>the gap fires can cause significant voltage stress across the outermost
>winding layers of the charging reactor. And, placing the de-Qing diode
>between the reactor and the gap really doesn't change this situation.
>Transformers and reactors that are specifically designed for HV testing or
>pulse work often use tapered windings to better "balance" the voltage
>stresses between winding layers to improve their robustness in the presence
>of high speed (spark breakdown) transients. Your DC reactor does not use
>these techniques and may be more vulnerable. I'd recommend adding a simple
>RC filter (such as the "Terry filter") between your charging supply and the
>spark gap to slow down high dv/dt transitions and prevent VHF parasitics
>from getting back into the charging reactor and diodes.
>Best regards and keep us posted on your progress!
>-- Bert --