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Re: [TCML] DC Resonant Coil Questions

Hi Bert,

Yes, I had gathered that the cap could be charged up to 2X the supplied DC voltage from reviewing Richie's site on the subject and I was figuring that I would likely have to operate in DC Res mode at a reduced voltage from my system's potential. I could slowly and carefully ramp up the voltage, which will be fairly simple with my main power panel variac. I figured that I will probably be able to run with the main varaic turned down significantly lower on the dial and still get a similar output from my coil to what would normally be obtained by running the control panel variac to a significantly higher dial setting for strictly AC asnch operation, assuming that the supply will remain stiff enough at the significantly reduced input voltage.

I have built my DC Res circuit on a Sam's Club special 15" x 20" poly cutting board in a completely separate and isolated unit from my main power control panel. This will allow me the choice to continue to operate with raw, unfiltered AC or insert the DC Res circuit assembly between the raw AC output from the control panel and pig and the inputs to the large coil. Going back to AC asynch will be accomplished by simply removing the portable DC Res circuit from the transmission lines.

I had even toyed with the idea of possibly using the HV side of one of my spare pole piggies as a heavy duty and robust oil-filled choke, albeit another ~250 lbs. to add to an already overly massive system! Or I could find a suitably sized leak proof container and simply submerse my current 5 H choke in oil inside the container....

I haven't really been very active in the coiling scene for the last few years, but seeing Roger's DC Res supply and the outstanding performance from his big coil driven by a DC Res supply has breathed some new life into my coiling endeavors. ;^)

Thank you for your expertise Bert,

----- Original Message ----- From: "Bert Hickman" <bert@xxxxxxxxxxxxxxxxxxxxx>
To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
Sent: Wednesday, August 10, 2016 11:47 AM
Subject: Re: [TCML] DC Resonant Coil Questions

Hi David,

Your component values look to be in the right ballpark for a target break rate of 350 BPS, and you should be able to push it to over 450 BPS. However, it looks like there's a "gotcha" in your system as currently proposed.

An ideal DC resonant system will apply 2X your DC supply voltage to your tank cap. Real world resonant charging systems typically develop 1.7 - 1.95X supply voltage depending on the "stiffness" of the supply, storage cap size, whether you're using single or multi-phase power, and the DC resistance of your charging reactor. At 280 volts input, the no-load output voltage for your FWB supply will be ~23.7 kVDC, and your tank cap can be initially charged to 40-45 kVDC! This will severely stress your charging reactor, tank caps, and rotary gap. You may want to limit your HV DC supply voltage to perhaps 12 kVDC prevent potentially damaging critical system components.

Good luck and best wishes,

Bert Hickman
Stoneridge Engineering, LLC
Alternative email: berthickman1@xxxxxxxxx
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