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Re: Transformerless Tesla coil
Original poster: "Jolyon Vater Cox by way of Terry Fritz <twftesla-at-qwest-dot-net>" <jolyon-at-vatercox.freeserve.co.uk>
Returning to the "trifilar balun" idea (but without the trifilar
winding)how about this:-
+------+----to ring
| |
L1 |
+ ----+--C1--+ |
| | |
| L2 C3
o | |
PSU gap +--+ |
o | | |
| L3 GND |
| | |
- ----+--C2--+------+
L1=L2=L3
C1=C2
C3=C1/3
Surely it is possible to design a 3-inductor balun which works with
NO magnetic coupling at all(similar to transformerless tesla coil) if
the output is a parallel-tuned tank circuit?
Wouldn't the use of non-coupled inductors avoid problem of
inter-winding breakdown associated with conventional transformer
baluns when used at high voltages?
Would common-mode voltages be a problem with this circuit too?
----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Monday, September 30, 2002 6:49 PM
Subject: Re: Transformerless Tesla coil
> Original poster: "Antonio Carlos M. de Queiroz by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <acmq-at-compuland-dot-com.br>
>
> Tesla list wrote:
> >
> > Original poster: "Jolyon Vater Cox by way of Terry Fritz
> <twftesla-at-qwest-dot-net>" <jolyon-at-vatercox.freeserve.co.uk>
>
> > The purpose of the network shown in my diagram was to solve two problems
> > inherent in driving a single end-grounded coil from a centre tapped HV
> > transformer, firstly, to isolate the output resonator from the high
voltage
> > power supply, and secondly, to protect the transformer from damage due
to
> > common mode noise. The split MMC would solve the first problem but would
not
> > solve the latter.
>
> Would reduce the common voltage level by 2.
>
> > Seen from the ring -to -ground side the network is parallel tuned tank
> > circuit of L1,L2,C2 and C3
> > L1 is equal to L2 and C2 is equal to C3. It is only necessary that
series
> > tuned circuit of C1 and L3 be resonant at the same frequency as the
parallel
> > tank.
>
> The impedance seen by the ring os ok, but this configuration charges
> C1, C2, and C3 with identical voltages (see picture) before the gap
> fires. The correct initial conditions would be charges (+ above and
> - below) in C2 and C3 only.
>
> > Also, looking from the ring to ground side if a signal were applied at
the
> > resonant frequency, two equal antiphase signals at the same frequency
would
> > appear at HV1 and HV2 respectively. The resultant signals would be
> > differential mode not common mode (unless I am mistaken!) The network is
> > passive so in theory it works the other way too.
>
> They would be common mode, as L1-L2 and C2-C3 form two identical
> voltage dividers. L3 and C1 would have no influence, as they and
> the transformer would be at the output of a balanced bridge.
>
> > On the latter point of the uncertainty of whether both gaps would fire I
> > have redrawn
> > the diagram below to show a single gap across both of the HV rails-
would
> > this not ensure
> > more reliable gap firing?
>
> Just to see what would happen, I run a simulation of the entire circuit
> using the values of a regular capacitive tranformer circuit L1a, C1a
> L2a, C2a, C3a, with C1=C1a, L3=L1a, L1=L2=L1a/2, C2=C3=2*C1a, and
> the other elements as in the original. The oscillation
> remains in C1-L3 only, with no energy transfer to the output...
> And there is common mode voltage in the gap.
> There is probably a way to design the network for correct operation,
> but I doubt that common mode voltages in the gap can be eliminated
> with this structure.
>
> +-----------to influence ring
> |
> +---+---+
> | |+
> L1 C2
> | |-
> HV1----+--C1--+ +--L3--+
> | + - | |- |
> | L2 C3 |
> | | |+ |
> CT-+ SG1 +---+---+ |
> | | | |
> GND | GND |
> | |
> HV2----+---------------------+
>
> Antonio Carlos M. de Queiroz
>
>
>
>
>