Re: RE: [TCML] mmc cap protection by spark-gaps-any ideas?

[CONOR WHYTE <cjwhyte@xxxxxxx>]

Yes, right.  Safety is a good idea. 
I should have made myself clearer.
I just had a bad experience with bulk resistors, I guess they were crap.
had they been exactly what I had ordered it would have been a less painful experience.
We aren't lucky like you guys in the US. we have charges on top of charges for anything. at that time it was 14.5% tax plus a stocking surcharge(fuel, time etc).
so much for it being "bulk".

Anyways... live and learn. 
I do recommend those CDE 942s though. Wow.. great capacitors!


----- Original Message -----
From: David Nelson <davidnelson11@xxxxxxxxxxx>
Date: Tuesday, August 19, 2008 8:35 pm
Subject: Re: RE: [TCML] mmc cap protection by spark-gaps-any ideas?
To: Tesla Coil Mailing List <tesla@xxxxxxxxxx>

> How much energy is lost in the MMC resistors? Surely it is a 
> small 
> percentage?
> 
> It seem to me that most people highly recommend them for safety 
> reasons.
> Dave Nelson
> ----- Original Message ----- 
> From: "CONOR WHYTE" <cjwhyte@xxxxxxx>
> To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
> Sent: Monday, August 18, 2008 2:01 PM
> Subject: Re: RE: [TCML] mmc cap protection by spark-gaps-any ideas?
> 
> 
> That was what I was trying to say. Some MMC designs I have seen 
> use an over 
> volt gap over the entire MMC to protect it. -- are you saying 
> this is a bad 
> idea? mike hammer used this design and it proved reliable for 
> him. 
> personally I have never used it. The caps i use allow me lots of 
> breathing 
> room. CDEs are simply awsome!!
> The resistors are safety for the operator. Like I said it is a 
> waste of 
> energy and $$.
> You can simply discharge a gap with a discharge wand after the 
> power is off.
> 
> 
> ----- Original Message -----
> From: S&JY <youngs@xxxxxxxxx>
> Date: Monday, August 18, 2008 12:26 pm
> Subject: RE: [TCML] mmc cap protection by spark-gaps-any ideas?
> To: 'Tesla Coil Mailing List' <tesla@xxxxxxxxxx>
> 
> > No, no, no! Don't do that! If one or more of the
> > gaps fires, the other
> > caps in series will overvolt which could cause them to
> > fail.
> >
> > The resistors are not to protect the caps. They are to
> > protect you from an
> > accidental dangerous shock by bleeding down the voltage stored
> > in each cap
> > in a few seconds after you turn off power.
> >
> > You can make good high voltage resistors by series connecting 5
> > 2 meg 1/4
> > watt resistors. Connect one of these resistor strings
> > across each cap.
> > Yes, lots of soldering, but the resistors are only 1 US cent
> > apiece (get
> > them in lots of 100 from Jameco).
> >
> > --Steve Y.
> >
> > -----Original Message-----
> > From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx]
> > On Behalf
> > Of vatercox@xxxxxxx
> > Sent: Sunday, August 17, 2008 3:23 PM
> > To: tesla@xxxxxxxxxx
> > Subject: [TCML] mmc cap protection by spark-gaps-any ideas?
> >
> > Dear List
> > I have 30 x 47nF polypropylene metal foil caps, each rated at 2
> > kVDC
> > which I intend to wire as three strings of 10 capacitors for
> > approximately 14nF at 20kV DC. While normally each capacitor in
> > an MMC
> > would be protected by a 10- or more megohm high voltage resistor
> > these
> > have proved difficult to obtain (due to lack of demand?). In liu
> > of
> > this would it be possible to protect each cap with a miniature
> > spark-gap -perhaps a pair of closely-positioned stiff wires
> > connected
> > to the capacitor leads notwithstanding the fact that 2 kV is
> > usually
> > regarded as a bit on the low side for satisfactory spark-gap 
> operation>
> > Jolyon Francis Vater-Cox
> > 
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