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Spark Gaps
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From: John H. Couture [SMTP:couturejh-at-worldnet.att-dot-net]
Sent: Friday, April 17, 1998 7:09 PM
To: Tesla List
Subject: Re: Spark Gaps
At 08:09 AM 4/16/98 -0500, you wrote:
>
>----------
>From: Malcolm Watts [SMTP:MALCOLM-at-directorate.wnp.ac.nz]
>Sent: Wednesday, April 15, 1998 11:21 PM
>To: Tesla List
>Subject: Re: Spark Gaps
>
>Hi John,
>
>> From: John H. Couture [SMTP:couturejh-at-worldnet.att-dot-net]
>> Sent: Wednesday, April 15, 1998 12:54 AM
>> To: Tesla List
>> Subject: Re: Spark Gaps
>>
>>
>> At 03:50 AM 4/13/98 -0500, you wrote:
>> >
>> >----------
>> >From: richard hull [SMTP:rhull-at-richmond.infi-dot-net]
>> >Sent: Sunday, April 12, 1998 5:05 AM
>> >To: Tesla List
>> >Subject: Re: Spark Gaps
>> >
>> >At 08:33 PM 4/11/98 -0500, you wrote:
>> >>
>> >>----------
>> >>From: Bert Hickman [SMTP:bert.hickman-at-aquila-dot-com]
>> >>Sent: Friday, April 10, 1998 10:25 PM
>> >>To: Tesla List
>> >>Subject: Re: Spark Gaps
>> >
>> >>Thratron or transistor switches were used by Richard Hull and Malcolm
>> >>Watts respectively to switch off primary current at earlier current
>> >>"zeros" (of the coil's fundamental operating frequency) during a number
>> >>of very interesting quenching experiments last year. Malcolm's attempts
>> >>to turn off a low-power transistor-switched primary circuit at points
>> >>other than primary current zeros did result in the expected high voltage
>> >>spikes stemming from rapid di/dt, but it's not clear that the an arc's
>> >>characteristics will permit this to actually occur under any reasonable
>> >>circumstance in higher power air-gap systems.
>>
>> ------------------------------------------------
>>
>> Did these tests quench dampened waves or pulsed waves?
>>
>> John Couture
>
>Not exactly sure what you mean. You can turn a transistor off any
>time you like. I tried turning off at first primary energy notch,
>first primary quarter cycle (thank heavens for parasitic zeners in
>the FETs), etc. It behaved just like a gap except it was a gap I
>could effect ideal quench/dwell times with. The test setup was a
>standard disruptive two coil system with k set to about 0.1
>
>Malcolm
>
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Malcolm -
I meant that because Tesla coils use dampened sine waves the quenching
would be different compared to quenching pulsed waves such as square waves.
Pulsed waves can have long off times where quenching would have no significance.
John Couture