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Re: Dramatic Performance Drop After 5 Seconds?
>Original Poster: "Lau, Gary" <Gary.Lau-at-compaq-dot-com>
>
>
>>>but thinking about it now... if you had an air flow across the gaps you
>>>may not have blown your caps ;)
>>>
>>>Scot D
>
>>I don't think so Scot. One parameter that's influencing positively the
>>induced primary voltage is dV/dT. When the spark is blown out by an
>airflow
>>the change in Voltage (dV) divided by the change in Time (dT) is
increasing
>>thereby increasing the induced Voltage in the primary coil and thereby
>>possibly over-stressing the capacitor. So, the opposite of your
proposition
>>is true. That's the reason that rotery gap's are working better than
>>stationary gap's.
>>
>>Ruud de Graaf
>>Greetings from Holland
>
>I don't see how airflow can possibly affect the dV/dT of the tank circuit.
>At the time of quench, the current through the gap is zero and the voltage
>on the on the tank cap is at it's diminished maximum value (few hundred
>volts) and minimum dV/dT. The maximum dV/dT occurs when the capacitor
>voltage is passing through zero (and gap current is maximum and quench is
>impossible), and is dependant strictly upon the peak capacitor voltage and
>the values of C and L, and any resistance in the tank circuit
>
>I agree that airflow across static gaps may reduce stress on tank caps, but
>the reason is that airflow improves quenching. The sooner the gap
quenches,
>the less time the tank circuit spends oscillating per bang-period.
>
>Gary Lau
>Waltham, MA USA
>
>
Hi Gary,
I was thinking about the 60hz wave. When you have a RSG you can see a
saw-tooth picture with possible eight tooths per wave. On that picture the
backside of the tooth's (spark) looks like the ideal dV/dT, but of course
when you zoom in to 200kHz, you can see a completely different picture. So,
I agree with you.
Ruud de Graaf
Greetings from sunny Holland