Re: Bleeder Resistors

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Qndre Qndre" <qndre_encrypt@xxxxxxxxxxx>

Hey Justin,

look at the schematics of your coil. It should look like this one: 
http://www.deepfriedneon.com/graphics/coil_schematic.gif

The "10 kV supply" is actually a transformer's secondary. If you shut 
down your power the capacitor acts as a power supply for the rest of 
the circuit. Now since the voltage is too low to make the spark gap 
fire you just ignore it. The circuits now looks like this: The 
capacitor is the power supply which drives two inductors which are in 
series: The secondary winding of the NST and the TC's primary coil. 
Since the wire of the inductor also has a resistance, it is like a 
resistor across the capacitor which will consume it's charge. This is 
why you won't measure a voltage across your capacitor.

However, it's better to have bleeder resistors across the capacitors 
for several reasons:

1. Imagine the secondary of your NST was broken during a run due to 
overload or whatever. Now you don't have a closed circuit any more 
which will make the capacitor hold a potentially lethal charge.

2. Capacitors do regain charge from dielectric memory which can be 
available to shock you whenever you make adjustments to your device. 
Since there are so many capacitors in series, this voltage can exceed 
several hundred Volts.

3. Even if the "whole MMC" is discharged because the coils consume 
the remaining charge, the capacitors WITHIN the MMC can still hold a 
charge. It's just that the MMC appears to be discharged because there 
is no voltage between both "ends". But this doesn't meain that there 
is no voltage across the single caps. If you accidently touch the 
capacitors you may be in for a surprise.

I'd suggest to use bleeder resistors across every single capacitor in 
the MMC for coils driven from the mains as well and not only for DC coils.

Regards, Q.

----Original Message Follows----
From: "Tesla list" <tesla@xxxxxxxxxx>
To: tesla@xxxxxxxxxx
Subject: Re: Bleeder Resistors
Date: Mon, 02 Jan 2006 11:31:07 -0700

Original poster: Just Justin <rocketfuel@xxxxxxxxxxxxx>

Can someone explain to me why this is not necessary?

I don't see why the tank cap seems to always be 'empty' (haven't actually
measured voltage for fear of zapping another meter) after a run.  If the
car was raised to almost-breakdown in the spark gap, shouldn't it stay
charged some of the times?

Justin


> Original poster: "D.C. Cox" <resonance@xxxxxxxxxx>
>
>
>
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> Bleeder resistor is not necessary unless you are running DC on this cap.
>
> Dr. Resonance
>
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> >I am using a .03 uF / 35,000 v Maxwell capacitor on a 15/60 NST
> >powered static gap coil.  Can a bleeder resistor be used on this
> >type of cap?  If so, what type of resistor is needed?  I'd
> >appreciate specs, brand, part number.  Thanks.  Dennis Hopkinton, MA
>
>