Re: DC coil

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

Original poster: "charles rakes by way of Terry Fritz <twftesla-at-qwest-dot-net>" <cdrakes-at-ipa-dot-net>

I'll try and make a drawing of the two TC circuits that I used.
NST Sec.
0------------->|-->|--------|
0                 diode string      |
gap
0-----gnd.
|----------------------------||||||||-------o
0                                         |                     ___|___
o
0               diode string        |                     ______     cap
o pri coil
0------------>|-->|---------|
|---------------------o
                                                                    gnd

                         Full wave bridge
0----------------|---->|---->|----|
0                        |                        |
gap
0----gnd            |
|------------|--------------|||||||||--------o
0                        |                        |                   |
o
0------|---------)---->|---->----|           ____|____
o  pri
            |             |                                    _________
cap                         o
            |              |-----|<---|<----|                   |
o
            |
|-------------|---------------------------o
            |---------------|<---|<---|


Boy, I hope the two drawings will do.  The top circuit works great with 21
inch streamers, however the bottom circuit does not perform at all.  The
only thing different between the two circuits is one used a full wave
rectifier circuit with the transformer's center tap as gnd giving about 1/2
have of the output voltage that the second circuit produces.....the bottom
circuit only change is to a full wave bridge circuit.  Must be a simple
explanation....but I've not found it.  Any clues?  Thanks once again.
Charles
Orinal Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Tuesday, November 05, 2002 9:03 AM
Subject: Re: DC coil


 > Original poster: "Daniel Barrett by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <dbarrett1-at-austin.rr-dot-com>
 >
 >      Not sure how you have it wired, but if you are just feeding the
output
 > of your bridge rectifier straight into your MMC, as if you just inserted
the
 > bridge between the NST and MMC, it won't work well. The problem is that
 > after the gap fires, the voltage on the MMC swings reverse. This forward
 > biases the bride diodes which burns off most of the MMC's charge in the
 > diodes instead of the primary. The solution is to install a great big
choke
 > between the bridge and the MMC.
 > db
 >
 > ----- Original Message -----
 > From: "Tesla list" <tesla-at-pupman-dot-com>
 > To: <tesla-at-pupman-dot-com>
 > Sent: Monday, November 04, 2002 8:36 PM
 > Subject: DC coil
 >
 >
 >  > Original poster: "charles rakes by way of Terry Fritz
 > <twftesla-at-qwest-dot-net>" <cdrakes-at-ipa-dot-net>
 >  >
 >  > Got a ?  I'm trying to get back into Tesla coil building, as I have a
 >  > little more time now, and throw together a simple DC coil using a
 >  > 15Kvolt  30ma NST with a full wave rectifier arrangement feeding the
.02uf
 >  > tuning capacitor.  With the transformer's center tap a ground I figure
I
 >  > was getting a little over 10k volts DC across the capacitor.  The coil
 >  > produces about 21 inch streamers with this set up.  So I figured if I
 >  > doubled the DC output voltage I  with a full wave bridge rectifier the
 >  > voltage would double.  Also the tuning should not change much,
 >  > right?  Anyway I put the circuit together and did increase the DC
output
 >  > voltage, however the coil's output is only about 1/2-inch sparks no
matter
 >  > how I try tuning it.  Am I missing something very simple.  Did revert
back
 >  > to the full wave circuit and had good response again?  Any ideas?? Tx
 > Charles
 >  >
 >  >
 >
 >