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Re: synchronous gap help (fwd)
---------- Forwarded message ----------
Date: Thu, 19 Jul 2007 04:34:08 -0700
From: Barton B. Anderson <bartb@xxxxxxxxxxxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: Re: synchronous gap help (fwd)
Hi Tony,
The LTR value of a cap is based on the transformers resonant cap value.
It is also based on specifically a Neon Sign Transformer running at 60
Hz in 120 bps operation (or 50 Hz at 100 bps). This is sometimes
forgotten. NST's were prone to over voltage secondary winding arcovers
internal to the transformer, and things like LTR were developed to
design out of a major resonance condition and also things like the Terry
Filter.
If you are running an NST at higher bps, just do some simple math to
accommodate an LTR value. Remember, the LTR is based on 60Hz input at
120 bps. So, if your running at say 240 bps, base the input on 120 Hz.
Thus, if you double the break rate, the LTR value divides in half. For
example, if at 60 Hz operation at 120 bps your LTR is .01uF, at 240 bps
your LTR value is .005uF.
MMC voltage ratings. That topic has had a lot of time on the list. The
smart thing to do is derate any cap bank. But many have rated their caps
barely above their cap voltage and the caps still do well. How long? Who
knows? I personally give a decent margin. I use a derating value of 2
times the DC rating for MMC's. I like derating, but I also don't want to
go overboard. Haven't lost an MMC cap since. I did early on previous to
derating to a value 2.
Take care,
Bart
Tesla list wrote:
>---------- Forwarded message ----------
>Date: Wed, 18 Jul 2007 23:11:10 -0700
>From: Anthony R. Mollner <penny831@xxxxxxxxxxxxx>
>To: Tesla list <tesla@xxxxxxxxxx>
>Subject: RE: synchronous gap help (fwd)
>
>Dear Dr. Resonance and the group,
> I'm not sure how that equates to the LTR cap value and the actual resonant
>cap value. Is there any rule of thumb or known value for a synchronous gap
>at 120 & 240 bps at 15/120? Another question of concern is cap voltage
>value. The MMC's might do well at their stated value for DC but, I had read
>that they should be valued at 2.8 times their DC voltage for use in AC
>applications. Any thoughts on that?
>
>Sincerely,
>Tony
>
>-----Original Message-----
>From: Tesla list [mailto:tesla@xxxxxxxxxx]
>Sent: Wednesday, July 11, 2007 12:13 PM
>To: tesla@xxxxxxxxxx
>Subject: Re: synchronous gap help (fwd)
>
>
>
>---------- Forwarded message ----------
>Date: Wed, 11 Jul 2007 14:05:28 -0500
>From: D.C. Cox <resonance@xxxxxxxxxxxx>
>To: Tesla list <tesla@xxxxxxxxxx>
>Subject: Re: synchronous gap help (fwd)
>
>
>
>
>Use 2.6 x matching impedance value for synchro sparkgaps.
>
>Resonance Research Corp.
>www.resonanceresearch.com
>
>
>----- Original Message -----
>From: "Tesla list" <tesla@xxxxxxxxxx>
>To: <tesla@xxxxxxxxxx>
>Sent: Tuesday, July 10, 2007 5:23 PM
>Subject: RE: synchronous gap help (fwd)
>
>
>
>
>>---------- Forwarded message ----------
>>Date: Tue, 10 Jul 2007 14:32:46 -0700 (GMT-07:00)
>>From: penny831@xxxxxxxxxxxxx
>>To: Tesla list <tesla@xxxxxxxxxx>
>>Subject: RE: synchronous gap help (fwd)
>>
>>I've already built the propellor gap using the .125 and the entire device
>>is housed in a cabinet with an blower to keep it cooled. I'll run it and
>>see how it does because as you said, the 1/4" is really expensive.
>>Adapting to the larger rods would be simple, just a few minutes on the
>>drill press! Does anyone have the Geek Group capacitor chart that includes
>>the cap value using the SRSG? I have the one for the static gaps but it
>>doesn't include anything for the SRSG. As always, thanks again.
>>
>>Tony
>>
>>-----Original Message-----
>>
>>
>>>From: Tesla list <tesla@xxxxxxxxxx>
>>>Sent: Jul 10, 2007 1:02 PM
>>>To: tesla@xxxxxxxxxx
>>>Subject: RE: synchronous gap help (fwd)
>>>
>>>
>>>---------- Forwarded message ----------
>>>Date: Tue, 10 Jul 2007 15:49:45 -0400
>>>From: "Lau, Gary" <Gary.Lau@xxxxxx>
>>>To: Tesla list <tesla@xxxxxxxxxx>
>>>Subject: RE: synchronous gap help (fwd)
>>>
>>>Red-hot with just a 15/120 NST? With my 15/60 NST and 5/32" tungsten
>>>rod, I can touch any part of the propeller-gap electrodes immediately
>>>following a 1-3 minute run. The stationary electrodes do tend to get
>>>hotter due to less airflow, but definitely not approaching
>>>incandescence.
>>>
>>>I don't mean to nit-pick, but 1/4" rod is a bit pricey and unnecessary,
>>>IMO.
>>>
>>>Regards, Gary Lau
>>>MA, USA
>>>
>>>
>>>
>>>>Date: Tue, 10 Jul 2007 14:04:49 -0500
>>>>From: resonance <resonance@xxxxxxxxxxxx>
>>>>To: Tesla list <tesla@xxxxxxxxxx>
>>>>Subject: Re: synchronous gap help (fwd)
>>>>
>>>>
>>>>
>>>>At this power level I would suggest 1/4 inch dia. electrodes. 1/8th
>>>>
>>>>
>>>inch
>>>
>>>
>>>>may overheat to redhot on the electrode tips and cause poor quenching.
>>>>
>>>>Resonance Research Corp.
>>>>www.resonanceresearch.com
>>>>
>>>>
>>>>----- Original Message -----
>>>>From: "Tesla list" <tesla@xxxxxxxxxx>
>>>>To: <tesla@xxxxxxxxxx>
>>>>Sent: Tuesday, July 10, 2007 11:07 AM
>>>>Subject: RE: synchronous gap help (fwd)
>>>>
>>>>
>>>>
>>>>
>>>>>---------- Forwarded message ----------
>>>>>Date: Tue, 10 Jul 2007 08:11:56 -0700 (GMT-07:00)
>>>>>From: penny831@xxxxxxxxxxxxx
>>>>>To: Tesla list <tesla@xxxxxxxxxx>
>>>>>Subject: RE: synchronous gap help (fwd)
>>>>>
>>>>>I have a related question on the propellor gap. I'm planning on
>>>>>
>>>>>
>>>pushing
>>>
>>>
>>>>>15/120 through an .125 thoriated tungsten electrode. Is that to much
>>>>>
>>>>>
>>>power
>>>
>>>
>>>>>for such a small electrode? Your thoughts would be appreciated.
>>>>>
>>>>>-----Original Message-----
>>>>>
>>>>>
>>>>>>From: Tesla list <tesla@xxxxxxxxxx>
>>>>>>Sent: Jul 10, 2007 7:27 AM
>>>>>>To: tesla@xxxxxxxxxx
>>>>>>Subject: RE: synchronous gap help (fwd)
>>>>>>
>>>>>>
>>>>>>---------- Forwarded message ----------
>>>>>>Date: Tue, 10 Jul 2007 08:55:27 -0400
>>>>>>From: "Lau, Gary" <Gary.Lau@xxxxxx>
>>>>>>To: Tesla list <tesla@xxxxxxxxxx>
>>>>>>Subject: RE: synchronous gap help (fwd)
>>>>>>
>>>>>>I think you're going to run into a problem using your relatively
>>>>>>
>>>>>>
>>>small
>>>
>>>
>>>>>>teletype motor to spin-up such a heavy 3/8" thick disk. I was
>>>>>>
>>>>>>
>>>barely
>>>
>>>
>>>>>>able to get such a motor to spin a 09" thick x 6.12" diameter G10
>>>>>>
>>>>>>
>>>disk
>>>
>>>
>>>>>>with just 4 brass acorn nuts electrodes, and it utterly failed to
>>>>>>
>>>>>>
>>>sync
>>>
>>>
>>>>>>with anything larger. I'd strongly recommend using a propeller gap
>>>>>>
>>>>>>
>>>if
>>>
>>>
>>>>>>using a Teletype motor. My SRSG page:
>>>>>>http://www.laushaus.com/tesla/sync_gap.htm, and Terry Blake's:
>>>>>>http://tb3.com/tesla/sparkgaps/index.html
>>>>>>
>>>>>>Regards, Gary Lau
>>>>>>MA, USA
>>>>>>
>>>>>>
>>>>>>
>>>>>>>---------- Forwarded message ----------
>>>>>>>Date: Mon, 09 Jul 2007 23:59:58 +0000
>>>>>>>From: ameen_ghavam@xxxxxxxxxxx
>>>>>>>To: Tesla list <tesla@xxxxxxxxxx>
>>>>>>>Subject: synchronous gap help
>>>>>>>
>>>>>>> I'm building a 240 bps srg for my tesla coil and was
>>>>>>>
>>>>>>>
>>>wondering
>>>
>>>
>>>>>>if
>>>>>>
>>>>>>
>>>>>>>anyone would give me any tips or suggestions. I'm planning to use
>>>>>>>
>>>>>>>
>>>a
>>>
>>>
>>>>>>3/8 "
>>>>>>
>>>>>>
>>>>>>>g10 rotor 8" in diameter with 4 1/4 " tungsten electodes held on
>>>>>>>
>>>>>>>
>>>with
>>>
>>>
>>>>>>>shaft collars (the disc is pinched between the collars). A sheet
>>>>>>>
>>>>>>>
>>>metal
>>>
>>>
>>>>>>>ring connects these electrodes. I have two stationary electrodes
>>>>>>>
>>>>>>>
>>>(one
>>>
>>>
>>>>>>>gap). My motor is a Teletype 1/12 hp motor, synchronous, and runs
>>>>>>>
>>>>>>>
>>>at
>>>
>>>
>>>>>>3600
>>>>>>
>>>>>>
>>>>>>>rpm. Any tips on how to balance, cut the g10 (i've heard its hard
>>>>>>>
>>>>>>>
>>>to
>>>
>>>
>>>>>>cut),
>>>>>>
>>>>>>
>>>>>>>motor arbor, or anything else I should know? Also, please email me
>>>>>>>
>>>>>>>
>>>off
>>>
>>>
>>>>>>the
>>>>>>
>>>>>>
>>>>>>>list. Thanks.
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>Cheers,
>>>>>>
>>>>>>
>>>>>>>Ameen Ghavam
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>
>>>>
>>>>
>>>
>>>
>>>
>>
>>
>>
>>
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