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Re: [TCML] Nearly First Firing



Ok, thats better, so that means I am looking at 30 - 40 nF and 16 - 20kV. I'm still going to have to wait to buy these parts but at least it gives me time to make the current circuitry safer and it gives me a chance to build a better Terry filter as well.

Thanks again

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

On 22 Jan 2009, at 21:26, Phil Tuck wrote:

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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