RE: Bleeder Resistors

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Lau, Gary" <Gary.Lau@xxxxxx>

With spark gap coils, with the coil off and the gap being an open
circuit, the tank cap, primary coil, and NST secondary form a loop, and
any charge in the cap is discharged essentially immediately through the
primary and NST.  But I disagree with the good Dr about a bleeder being
unnecessary.  They're unnecessary the same way seat belts are
unnecessary.  Should the primary tap connection or NST secondary
connection come loose, the discharge path is lost.  In my early coiling
days I once tried to determine the best primary tap point by dragging
the tap connection across the primary turns, while it was operating.
The arcing between the tap wire and the primary was fierce and I
abandoned that idea immediately.  But I quit with the tap disconnected.
When I shut off the power and attempted to make the tap connection, I
got a very stiff ZAP, and I was lucky that the cap didn't carry a larger
charge.

In short, "stuff" happens, and having a backup discharge path (bleeder)
in place is cheap insurance.  You won't be able to find a single
off-the-shelf resistor at a reasonable price capable of the job, but one
can easily build a series array that will withstand the voltage.  The
resistance value is not critical; probably anything between 50-100 Meg
is OK.  I made an array of 39 2Meg 1/4W resistors, 'cause that's what I
had available.  See photo about half way down on my RSG page:
http://www.laushaus.com/tesla/sync_gap.htm

Regards, Gary Lau
MA, USA


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>
 >
 >
 >
 >
 > Bleeder resistor is not necessary unless you are running DC on this
cap.
 >
 > Dr. Resonance
 >
 >
 > >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
 >
 >