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RE: [TCML] Nearly First Firing



Simon
Relax, stay calm. I should have said 1.5 to 2 times. The 2 to 2.5 I quoted
relates to what voltage rating you want aim for to play safe.  (x2 is a
minimum, x 2.5 is better, 3 is good)
Bart's JavaTC gives 0.0298 uF (and I've found that program to be right about
most things)   (PayPal please Bart)
 
Phil


-----Original Message-----
From: Simon Dodd [mailto:simon@xxxxxxxxxxxxxxxx] 
Sent: 22 January 2009 16:31
To: Tesla Coil Mailing List
Subject: Re: [TCML] Nearly First Firing

Sorry to keep on with this, If I'm requiring 19.8nF @ 20kV then would  
it be OK to use 6 strings of 15 caps using the 47nF @ 1500V The figure  
is slightly off from exactly what I need but is it within working  
tolerances?

The caps are the ones from RS labelled: KP172 axial polyprop cap,47nF  
1.5kV
Part Number: 114-474

Thanks again for all your help, I wouldn't be at ths stage without all  
your continued support, I am going to try and get it finished for the  
Teslathon in March even though it is a fair distance from me...

-- 
Simon Dodd
Director/ Technical Manager
Yes Boss Music
simon@xxxxxxxxxxxxxxxx
07828467411
www.yesbossmusic.com

On 22 Jan 2009, at 15:59, Simon Dodd wrote:

> Just realised that I measured the caps in the circuit and with the  
> bleed resistors still attached, does that make a big difference?   
> Looks like RS are going to be taking my first paycheck from my new  
> job then!!
>
> Looks like the project is on  hold for a while then!! I might  
> construct one of the big filters in the mean time!!
>
> Thanks for all your help so far, I'm sure Ill be back soon when I  
> have the right caps!!
> -- 
> Simon Dodd
> Director/ Technical Manager
> Yes Boss Music
> simon@xxxxxxxxxxxxxxxx
> 07828467411
> www.yesbossmusic.com
>
> On 22 Jan 2009, at 15:10, Lau, Gary wrote:
>
>> The 35 Ohm reading - is that with nothing else in the circuit, just  
>> the caps?  An Ohmmeter should read open-circuit on a capacitor or  
>> bank of capacitors like this.  If it's reading 35 Ohms, one or more  
>> of them is toasted.
>>
>> OK, I see your caps on
http://www.rmcybernetics.com/shop/surplus-science-lab-equipment.htm?show=hv#
A28 
>>   It says: "These capacitors are ideal for projects such as voltage  
>> multipliers and small DC Tesla Coils".  Vendors will always say  
>> that stuff is ideal for use in Tesla Coils when it isn't.  EBay is  
>> particularly bad with this.  These are disc capacitors.  I'm not  
>> sure what a "small DC Tesla coil" is, but they're no good for what  
>> you need them for.  Sorry!
>>
>> Regards, Gary Lau
>> MA, USA
>>
>>> -----Original Message-----
>>> From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On
>>> Behalf Of Simon Dodd
>>> Sent: Thursday, January 22, 2009 9:18 AM
>>> To: Tesla Coil Mailing List
>>> Subject: Re: [TCML] Nearly First Firing
>>>
>>> I am reading 35 ohms across the whole capacitor bank. I got the caps
>>> from rmcybernetics website. They were sold as ideal for tesla  
>>> coils, I
>>> will be looking at getting some of the big pulse caps from RS as  
>>> soon
>>> as my bank balance is healthier...  I now have 19 in parallel giving
>>> me .02uF give or take and my NST needs .01989uF for complete  
>>> resonance
>>> so it should be OK. I will be waiting till later in the day to test
>>> again as there are a lot of businesses around me who would get very
>>> annoyed with me I feel...
>>>
>>> Thanks again for all your help and anything else you can think of  
>>> that
>>> may help me would be greatly appreciated.
>>> --
>>> Simon Dodd
>>> Director/ Technical Manager
>>> Yes Boss Music
>>>
>>>
>>> On 22 Jan 2009, at 13:41, Lau, Gary wrote:
>>>
>>>> Hi Simon,
>>>>
>>>> OK - it's clear that the cap value is not excessively high.  For an
>>>> 8/50 NST @50Hz, a mains-resonant cap would be .02uF, so for an LTR
>>>> design one would shoot for .03-.04uF.  I think you presently have .
>>>> 016uF.
>>>>
>>>> So the NST looks good, but I'm not so sure about the caps.  Are  
>>>> your
>>>> caps disk capacitors?  Ceramic caps are rarely suitable.  Some
>>>> doorknob caps are, but disk caps are never suitable.  They tend to
>>>> have high losses and consequently get hot, quickly, and die.  And
>>>> the temperature coefficient is awful, and change value as you look
>>>> at them.  Is it possible that one or more of them is shorted?  It's
>>>> not a definitive test, but what does an Ohmmeter read across them?
>>>>
>>>> Regards, Gary Lau
>>>> MA, USA
>>>>
>>>>> -----Original Message-----
>>>>> From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx]  
>>>>> On
>>>>> Behalf Of Simon Dodd
>>>>> Sent: Thursday, January 22, 2009 5:21 AM
>>>>> To: Tesla Coil Mailing List
>>>>> Subject: Re: [TCML] Nearly First Firing
>>>>>
>>>>> Ok, I just got an answer back from Tunewell and it turns out my
>>>>> transformer is only 8Kv @ 50mA!  I will be adding the relevant  
>>>>> caps
>>>>> to
>>>>> my MMC and hopefully the rain will stop so I can try for test
>>>>> firing 2
>>>>> tonight! Hopefully with pictures or videos for you all to see!!
>>>>>
>>>>> On 21 Jan 2009, at 20:20, Simon Dodd wrote:
>>>>>
>>>>>> Cheers Gary,
>>>>>> Its a conventional heavy core transformer as far as I'm aware.  
>>>>>> It is
>>>>>> an old one and its very heavy!!   The caps are high voltage  
>>>>>> ceramic
>>>>>> caps from rmcybernetics.com
>>>>>>
>>>>>> Thanks
>>>>>>
>>>>>> On 21 Jan 2009, at 20:06, Lau, Gary wrote:
>>>>>>
>>>>>>> Is the NST a conventional, heavy core and coil transformer or a
>>>>>>> lightweight solid state inverter type?  You need the core and  
>>>>>>> coil
>>>>>>> type.
>>>>>>>
>>>>>>> What kind of caps are these?
>>>>>>>
>>>>>>> Regards, Gary Lau
>>>>>>> MA, USA
>>>>>>>
>>>>>>>> -----Original Message-----
>>>>>>>> From: tesla-bounces@xxxxxxxxxx [mailto:tesla- 
>>>>>>>> bounces@xxxxxxxxxx]
>>>>>>>> On
>>>>>>>> Behalf Of Simon Dodd
>>>>>>>> Sent: Wednesday, January 21, 2009 2:42 PM
>>>>>>>> To: Tesla Coil Mailing List
>>>>>>>> Subject: [TCML] Nearly First Firing
>>>>>>>>
>>>>>>>> Hi Guys,
>>>>>>>>
>>>>>>>> I went for first light this evening!! Unfortunately there was
>>>>>>>> nothing!
>>>>>>>> My spark gap fires when there is no capacitor bank in place  
>>>>>>>> but as
>>>>>>>> soon as I put my MMC into the circuit and connect the main  
>>>>>>>> parts
>>>>>>>> of
>>>>>>>> the coil, the spark gap stops firing :-(  I am using a 10Kv NST
>>>>>>>> with a
>>>>>>>> static spark gap and 16, 20Kv 1000pf capacitors in parallel.  
>>>>>>>> These
>>>>>>>> are
>>>>>>>> from the calculations on deepfriedneon.  The spark gap will  
>>>>>>>> fire
>>>>>>>> if
>>>>>>>> the lead to the outer ring of the primary is left unconnected.
>>>>>>>>
>>>>>>>> Im sorry its not too clear, I can do a quick diagram if you  
>>>>>>>> want
>>>>>>>> more
>>>>>>>> info.
>>>>>>>>
>>>>>>>> Thanks for your help again
>>>>>>>>
>>>>>>>> Simon
>>>>
>>>> _______________________________________________
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>>>
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>
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