Re: DC POWER

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

Original poster: "S & J Young by way of Terry Fritz <twftesla-at-qwest-dot-net>" <youngs-at-konnections-dot-net>

Chris & other DC coilers,
 
Here is the way to use a SPDT RSG that does work rather well!  I will switch to
Courrier New and try some ASCII art to illustrate it.  The idea is not mine (is
Deano's), but I tried it and it works very well.
 
                                                      spdt RSG
+ ----------------------O         O--------
                         \                |
                          \               |
                           \              |
                            O             |
DC                          |             | 
Supply                      |             |                     
                tank cap   ===            |
                            |             |
                primary     -at-             |
                            -at-             |
                            -at-             |
                            |             |
- -----------------------------------------  
 
By charging the tank cap with the primary in series, you get a "bang" for each
position of the switch, and the inductance of the primary greatly reduces the
stress of the tank cap being charged.  So you get double the BPS and fairly
efficient operation.  No power wasting series resistor is required.  The DC
supply does require a filter cap of at least 20 times the capacitance of the
tank cap.
 
Even better is the H-Bridge configuration, which is a dpdt RSG.  It alternately
reverses the polarity across the series connected tank cap and primary,
effectively doubling the voltage across the tank cap, making much more
energetic "bangs".  The RSG is much more complicated and will have more losses,
of course.  I will be soon be reporting my results of such an arrangement. 
Larry Robertson reported great results with this configuration a few years
ago.  Either the H-Bridge or the above arrangement can have any BPS you want,
and the power supply requires no ballasting.
 
--Steve Young
 
 
 
----- Original Message ----- 
From: "Tesla list" <<mailto:tesla-at-pupman-dot-com>tesla-at-pupman-dot-com>
To: <<mailto:tesla-at-pupman-dot-com>tesla-at-pupman-dot-com>
Sent: Friday, March 01, 2002 4:24 PM
Subject: RE: DC POWER

> Original poster: "Chris Swinson by way of Terry Fritz
<<mailto:twftesla-at-qwest-dot-net>twftesla-at-qwest-dot-net>"
<<mailto:exxos-at-cps-games.co.uk>exxos-at-cps-games.co.uk>
> 
> Hi Nick,
> 
> 
> > Mark Barton, Brian Steinbach and more recently Steve Young all tried the
> > SPDT approach, all reported rather poor efficiencies. (and in Mark's case
> > some fairly extreme collateral damage as I recall)
> 
> Do any of these have a website ?
> 
> >
> > If you could draw the exact circuit that would be helpful.  My old DC
> setup
> > had a nasty habit of blowing diodes in the snubber stack unit I added some
> 
> 
> FTM my scanner is not working, but some chap yesterday posted a design which
> is basically the same, which is at
> 
>
<http://www.mindspring-dot-com/~ottalini/DCCOILS/Dcschema2.jpg>http://www.mindsp
ring-dot-com/~ottalini/DCCOILS/Dcschema2.jpg
> 
> I do however have a smoothing cap 2MFD across the NST DC output.  Where he
> has a 10K I have tried a spark gap, resistor, and inductor now. HTH.
> 
> 
> > extra protection circuitry.  To both limit the charging current and
> prevent
> > the voltage reversal blowing out the rectifier you put a large inductance
> in
> > series with the output of the supply.  However this only _reduces_ the
> > kickback, you then need to add a supply snubber network (appropriately
> rated
> > of course) in between the filter cap and the charging reactor to keep the
> > transients out of the filter and shunt them off to ground.  The resonant
> > charging approach, using a reactor, is imho the _only_ way to go, if you
> > want reasonable efficiency from a DC system.  Suitable charging inductors
> > can often be had from old radar systems, as I said Martin is the man to
> > speak to.
> 
> Yes it might help a bit, though my diodes are running a a bit of a push
> really so that don't really help to much.
> 
> 
> 
> cheers,
> chris
> 
> 
> 
> P.S. I tried to send a copy to your mail box  at tcbouk-dot-org.uk though I got
> it back with the servers life history so it seems...
> 
> 
> 
>