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>

Dave,

You could simply kill two birds with one stone - connect all of your DC 
storage caps in series so that your bank capacitance is 1.75 uF instead of 
7 uF. Leave the existing pairs of 100 meg resistors across each capacitor 
(for DC voltage balancing across the chain) and add three 100 Meg bleeders 
in parallel across the entire bank. This will reduce the stored energy in 
the bank to 1/4 of what it was previously - still more than adequate. It 
will also drop Tau down to ~50 seconds so that the bank voltage decay to a 
safe level of less than 45 volts after five minutes.

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>
>I agree. I am going to add an additional resistor which should reduce the
>time to 15 minutes or less. I will measure the time reduction to ensure the
>discharge time meets expectations.
>A friend suggested that I also add a discharge switch to immediately safe
>the smoothing capacitors for just the purpose you suggest. That way
>adjustment can be made immediately. I will investigate this.
>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 5:12 PM
>To: tesla-at-pupman-dot-com
>Subject: Re: DC Resonance Charging Advice Sought
>Original poster: "Crow Leader by way of Terry Fritz <teslalist-at-qwest-dot-net>"
><tesla-at-lists.symmetric-dot-net>
>----- Original Message -----
>From: "Tesla list" <tesla-at-pupman-dot-com>
>To: <tesla-at-pupman-dot-com>
>Sent: Tuesday, August 12, 2003 9:52 AM
>Subject: RE: DC Resonance Charging Advice Sought
>
>  > Original poster: "Dave Kyle by way of Terry Fritz <teslalist-at-qwest-dot-net>"
><dave-at-kyleusa-dot-com>
>  >
>  > Thanks for the feedback. Yours is the first advice I have seen that
>suggests
>  > the sizing of the smoothing caps. I admit the smoothing caps value was
>  > pretty much determined by finding a good deal on eBay and you may be
>right
>  > that it is over kill (pun intended) in this application.
>  >
>  > To be honest the DC supply scares me to death which is probably a good
>  > thing. Obviously it is certain death to contact almost any part of it
>while
>  > it is on with or without the caps. My main concern is to safe the caps
>after
>  > operation to ensure inadvertent contact does not result in tragedy.
>  >
>  > I have bleeder resisters (two 100 megaohm 3 watt -at- 15KV in parallel) in
>  > place on each cap that take the smoothing caps with a full charge to safe
>  > values in about 35 minutes.
>This seems like a long time. Pretend your tesla coil was completely
>harmless. When making adjustments, you'd probably want to wait less than 35
>minutes after powering it off to make changes. Unless you're amazingly
>patient, it sounds like you might eventually get tired of waiting 35 minutes
>and start shorting the caps out yourself. The whole "safety" is then
>defeated. Utility company caps are designed to drop to 50 volts or less in 5
>minutes. I'm not sure if it's some NEMA standard, or who else uses it, but
>it sounds reasonable. Microwave ovens drop to safe voltages in just a few
>minutes as well.
>KEN