RE: [TCML] DC coils

["Gary Lau" <glau1024@xxxxxxxxx>]

The proposal to charge the capacitor through a second gap seems shaky to me.  In a spark gap, the gap conducts for only a very brief interval (very low duty cycle), whereas the capacitor typically needs to charge for ~99% of the bang interval.  It can’t possibly be charged in the duration that a gap conducts.  What am I missing?

Regards, Gary Lau
MA, USA

From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On Behalf Of lightningfor@xxxxxxxxxxxxxxxxxxxxxx
Sent: Thursday, January 27, 2011 4:48 PM
To: Tesla Coil Mailing List
Subject: RE: [TCML] DC coils


Hi Steve,
Thanks for that.
What would you estimate the losses to be like by charging the capacitor
through a spark gap?

Thanks.

On Wed, 26 Jan 2011 18:43:28 -0700, "S&JY" <youngs@xxxxxxxxx> wrote:
> Carlos,
>
> 
>
> Great choice to go with DC! 
>
> 
>
> With the usual DC powered Tesla Coil using a charging reactor and
De-Q-ing
> diode, you have to use a break rate above a certain minimum, or the
rotary
> spark gap will start power arcing.  You are probably familiar with
Richie's
> wonderful website, specifically
> http://www.richieburnett.co.uk/dcreschg.html#resonant which gives a very
> good explanation of DC resonant charging Tesla Coil theory and practice.
A
> good side benefit of this scheme is that you end up charging your
primary
> capacitor to nearly twice your supply voltage.
>
> 
>
> I worked out a better way to do DC resonant charging which I use on my
> coils.  With this method, your break rate can be as slow as you want
with
> no
> power arcing or other bad effects.  And your break rate can be as high
as
> you want, subject to the current capability of your DC supply.  A
further
> benefit is that when your primary capacitor discharges into your
primary,
> the power supply is completely disconnected from the primary circuit.
>
> 
>
> To do this requires a second gap on your RSG.  The gaps are arranged so
> that
> one gap charges your MMC capacitor through a charging reactor (only
needs
> to
> be a fraction of a Henry) and a De-Q-ing diode.  Then the rotor rotates
so
> that the second gap discharges the MMC into your primary.  Further
rotation
> repeats the cycle - charge the MMC from your power supply then discharge
> the
> MMC into your primary.
>
> 
>
> DC coils are fun.  You can vary both the supply voltage and the RSG
break
> rate.  As you can imagine, the higher the break rate, the more "robust"
are
> the streamers.  For my coils, break rates in the 200-250 range seem to
be
> the sweet spot for best streamer length vs power input.
>
> 
>
> My HV rectifiers are strings of 1N5408 1000 volt 3 amp diodes with
enough
> diodes in each string to be rated for roughly twice the highest voltage
> they
> must handle.  They can handle charging current pulses of 30 amps at 400
> bps.
> This is the least expensive approach.
>
> 
>
> Please let us know how your DC coil works out.
>
> 
>
> --Steve Y.

_______________________________________________
Tesla mailing list
Tesla@xxxxxxxxxx
http://www.pupman.com/mailman/listinfo/tesla