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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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