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Re: spark gaps



At 11:08 PM 10/17/96 -0600, you wrote:
>>From jim.fosse-at-bdt-dot-comThu Oct 17 22:59:49 1996
>Date: Fri, 18 Oct 1996 04:43:45 GMT
>From: Jim Fosse <jim.fosse-at-bdt-dot-com>
>To: tesla-at-pupman-dot-com
>Subject: Re: spark gaps
>
>
>>Date: Wed, 16 Oct 1996 19:39:16 -0500 (CDT)
>>From: Mike Hammer <mhammer-at-midwest-dot-net>
>>To: tesla-at-pupman-dot-com
>>Subject: spark gaps

>[snip]
>>3. I have seen references to vacuum gaps in the archives but very few details.
>>   Could somebody who has built one give some details and what kind of results
>>   were obtained. 
>>
>Check out 
>
>	Surplus Center
>	1015 West "O" Street
>	P.O. box 82209
>	Lincoln, NE 68501-2209
>	800-488-3407
>	402-474-4055
>	402-474-5198 (fax)
>
>on page 121 of the '96 catalog:  Item: 16-1048 is a 60 CFM 115V blower
>
>	115 VAC
>	3450 RPM
>	1/9 amps
>	5 stage blower
>	18" H2O vacuum at 0 CFM
>	60 CFM open outlet
>	10" dia by 10"
>	18 lbs.
>
>	$18.95 U.S.D. plus shipping;( not to bad.
>
>IT's quite! I've used one for 2 years for a shop vac when I'm not
>blowing my gap;) It will really quench your gap.
>

OK I will check that out. I'm pretty sure I have a copy of their catalog around
here somewhere.

So then I just suck air through a regular static gap with a vacuum cleaner
motor?
How would that be different than blowing air through it with a blower or fan?
I can see that with a really strong vacuum the velocity might be greater.



>
>>4. The message I get from the list archives is that rotary gaps are not 
>>   for neons. The message is loud and clear that using a rotary on a neon
>>   is inviting transformer failure. Why? What is it that promotes a failure?
>>   I'm not likely to build a rotary anytime soon but would like to know just 
>>   the same.
>>
>Mike,
>	Think about a static gap: it's just sitting there waiting for
>the voltage to rise above it's breakdown voltage (10KV - 15KV) ... The
>voltage across the neon will not exceed this value.
>
>NOW think about a rotary gap. It is NOT just sitting there waiting for
>the voltage to rise above it's breakdown voltage........ No, it's
>rotating; and changing it's breakdown voltage, to many hundreds of KV
>at max spacing. So the voltage across the neon will rise, to the
>neon's output voltage times the "Q" of the neon's leakage inductance/
>primary cap, to the breakdown voltage (100KV??) of the rotary gap.
>Eventually, the phase of the "resonant voltage" and the rotary's
>breakdown voltage will max ( at several hundred KV) and the poor neon
>will blow.


Now that makes sense. In fact it is rather obvious if you think about it.





>
>	jim
>

Mike Hammer
mhammer-at-midwest-dot-net