RE: I'm going to need help with a 34kV power supply

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Loudner, Godfrey by way of Terry Fritz <twftesla-at-qwest-dot-net>" <gloudner-at-SINTE.EDU>

Hello Chris

You mentioned testing 20 such power supplies. Are some of them for sale?

Godfrey Loudner

> -----Original Message-----
> From:	Tesla list [SMTP:tesla-at-pupman-dot-com]
> Sent:	Friday, November 02, 2001 7:19 PM
> To:	tesla-at-pupman-dot-com
> Subject:	Re: I'm going to need help with a 34kV power supply
> 
> Original poster: "Chris Brick by way of Terry Fritz <twftesla-at-qwest-dot-net>"
> <cbrick-at-rebelbase-dot-com>
> 
> 
> >Greetings, all!  :)
> >    A while back, I got my hands on a 34kV 120ma pulsed DC power supply
> from
> >a laser assembly.  To date, I've only ever used it in a jacob's ladder
> and
> >it was able to span a 7" gap pretty easily.
> 
> You got that little guy from me.  Glad to hear you are going to use it on
> a 
> coil.  They do make for a pretty serious jacob's ladder supply.
> 
> >    That said, I'm now itching to use that pretty gold box to power a
> larger
> >tesla coil.  I realize that the extremely high voltage from this power
> >supply is going to cause some major design problems with the primary
> >circuit.  I have enough pulse caps to hold off 140kV and give me 7.5nf.
> The
> >caps will obviously have to be immersed in oil, the connections and
> wiring
> >between all of the components will all have to be heavily insulated and
> >probably coated with an insulator to keep corona losses down, but I'm not
> >sure about the construction of the primary coil.  I'll most likely use
> 3/8"
> >copper tubing, but how far apart should the turns be spaced?.
> 
> The power supply has a variable voltage output.  They are current source 
> power supplies so the current level will start off high and as it reaches 
> the set voltage, the unit will stop charging.  If I understand this 
> correctly, it will push the current out as fast as possible until the 
> voltage setting is reached.
> 
> I am currently using 4 of these supplies in parallel on my large coil 
> system.  Initial testing has produced some 15ft arcs to the ground from my
> 
> 9ft tall coil.  I am currently running NO protection devices.  Just the 
> power supplies directly to the tank circuit.  So far so good but
> protection 
> circuits will go in before long.  It appears that there is a large diode
> on 
> the HV output terminal.  I need a larger, smoother toroid and to do some 
> major tuning but the results are very good so far.
> 
> >    The spark gap is another problem.  I'd like to use an async rotary
> with a
> >good bit of radial velocity (3450rpm, instead of 1725rpm), but what would
> be
> >good to use for the stationary electrodes so that they won't glow with
> >corona and ionize the air around the gap excessively?  Would a nice fan
> take
> >care of that, or should something like a small doorknob be used?
> >    If I go with a static gap, I worry about corona losses at the edges
> of
> >the copper pipes, if copper pipes are the best choice for this gap.
> 
> I am using a sucker single static gap at the moment (Gary Lau style).  It 
> works very well.
> 
> >    How do you feel about a triggered gap?  The trigger electrode would
> have
> >to be powered with a significant amount of voltage, given that that tank
> >circuit will be powered with a 34kV power supply.
> 
> I am planning to build a triggered gap for my coil but will hopefully be 
> able to design a controller that will allow variable breakrate since there
> 
> is no 60hz wave in the tank circuit.
> 
> >    Any advice on how to properly design and build such a high-voltage
> beast
> >would be greatly appreciated.  I won't mind comments about safety,
> either,
> >as I don't want to miss any issues on safety just because I hadn't
> >remembered them at the time.
> 
> Like I said above, you can limit the voltage to the coil at the 
> controller.  I love running a coil from a little plastic box with few 
> switches and a potentiometer.
> 
> Since these power supplies use ground as one side, one side of the tank 
> circuit must be connected to ground.  On my coil, this is the bottom of
> the 
> secondary, inside turn of the primary, and one side of the spark 
> gap.  After running the coil, I have to place a resistor network across
> the 
> cap bank to make sure there is no charge left .  This is something you may
> 
> need to do also.
> 
> For anyone interested in some pictures of the power 
> supplies:  http://www.teslacoils-dot-org/rcs1000/index.html
> 
> I will have my new website up in a short while with lots of pictures of my
> 
> big coil as well as some text about the whole project.
> 
> Chris
> 
>