Re: Volltage Multipliers/DC supplies

    In general, I have noticed that they typically are using transformers as
the means of multiplying voltages.  Using DC techiques really produce the
same results.  In other words every time you double the voltage you are
still halving the current.  So, as far as power conversion is conserned it's
just more effective, and effecient to use line current, and step up straight
off of the line.  A DC voltage doubler using capacitors would result in a
capacitor bank, which could blow at any point, and cost more overall.

    I noticed that using transformers in phase, you can place the primary in
parallel, and the secondarys in series, which will produce the output
voltage of Ts1+Ts2 if the model, and make of the transformers are the same.
If you were using auto-transformers there would be a phase relationship
problem in respect to ground where Ts1+Ts2 = 0 because the outputs of the
secondarys would be out of phase using a proper grounding scheme on both
transformers.  When you look auto-transformer, the windings are tapped, and
continuous, and the tap represents the primary, and one of the output leads
of the secondary.  Properly grounding an auto-transformer consists of
grounding the shared lead.  Now, using the same make and model of
transformer, and placing the primarys in parallel would cause the output to
be 180 degrees out of phase.  The result is Ts1+Ts2 = 0.

    Now, if you are using transformers where the primary windings are
isolated from the secondarys, and the transformer is a classical isolation
transformer.  Then the primary, and the secondary are two seperate windings
on the same form, seperated by a layer of paper, and enamel.  That is a
standard construction technique for that kind of transformer.  Now, a spark
plug coil is an auto-transformer, and you measure the resistance of the
primary, and the secondary in series but, with an isolation transformer
there is not conductive bridge between the primary, and the secondary.

    Using two isolation transformers with the primarys in parallel, and the
outputs in phase, you can connect the outputs of the two transformers in
series, and this is true for any number of transformers but, the power
ratings in watts = T1 + T2, and on the primary that winds up being the
current of T1 + T2, and on the output its the voltage of T1 + T2 as a result
of being in phase.

    If you don't know which wire to use, you can match colors but, on some
transformers you would have to do the detective work yourself.  Here is how
I do it.  I take a neon bulb from radio shack, and there are two posts
inside the bulb, if DC is applied to the neon bulb the negative post glows.
Then I use a standard 1.5v battery, and watching the polarity use tape to
mark the negative pole.  If one wire is striped for the primary, and the
other is not, then I make one wire negative for testing both transformers.
Okay, now right when I connect the 1.5 volt battery a voltage is induced on
the secondary, and the neon bulb is connected to the secondary wires.  I
simply mark the side where the post inside bulb flashes the brightest, and
then I know which wire is negative as the result of a negative pulse.  Then
I stick a piece a tape on that one.  Now, when hooking it up to the power
plug, I need both tape marked wires on the same prong on the primary.  Then
I need to join one marked with tape to one that's not on the secondarys, to
join T1 to T2 properly.  Then one of the two wires not connected to anything
yet are labled ground, and output.  This way you can get twice as much
voltage at the same current as the transformer T1, or T2 is rated for.  Now,
when measure the voltage of the output from Vout, to the joining of T1, and
T2, you will read the same voltage as the transformer is rated for as an
output.  From the joining of T1 to T2 to Ground is the same as the
transformer is rated.  But, from Out skipping the joining, to Ground is
double the output rating of T1, or T2, and it won't burn out that way, nor
will it heat more than normal.  So, if a neon transformer would give you 35
Kv at 30 mA, you would have 70 Kv at 30 mA by using two.  You could take
little ratty isolation transformer, or flat packs and do the same, and
eventually have 35, or 70 Kv if you wanted.  Surplus transformers sometimes
only cost a buck a piece, and you can make it happen.  Audio transformers
can bring a world of surprises 41KHz as step up transformers.  The is at 300
V, and they run pretty cool at 1 mA out.  4 of em' and you've got 1.2 Kv so,
it would 117 of em' to reach 35 Kv.  So, a spark plug coil is much more
appealing at around 100 Kv.

    I don't know where you live but, if you fish a box like one of these and
two ground rods for the secondarys make an excellent means of gathering
worms.  If you have beach front property the same technique needs to be
tested for getting clams to dig themselves out.  I have seen so many worms
do just that I wouldn't be surprised but, I would use a plastic bucket to
stand in until I shut the circuit down.  I have recieved a few ground shocks
standing between the grounding rods, which are usually 1/4 inch steel rods
threaded on one end.  There isn't enough to stun a fish in any of it, so
it's only good for baiting a hook.



>Original Poster: "ROBERT CRESSLER" <59CREROB-at-menasha-dot-com>
>Hi All,
> I have notice there is not much said about
>multiplies and DC supplies in
>general........ is this because of "intrinsic" problems with the
>components at the required voltages ? kickback/transients ?  or  ?
>Robert Cressler
>Oregon city, Or