Re: 465 Multiplier Mistery!

Fabio Trevisan
 

Hi Chuck,
3 round diodes + 3 round capacitors would be an interesting interpretation,
but it wouldn't make up for the 3x multiplication factor that the 465
requires.
The 465 has one single transformer winding feeding at the same time the
cathode rectifier to -2450V (thus a 4900Vpp output) and the input of the
multiplier which, at its output must deliver 15kV (thus a 3x multiplier in
terms of p-p figures).
A 3 diode + 3 capacitor multiplier can only make 1.5x (in the same p-p
figures).
I have tried a few times to break open color TV flyback transformers, which
have embedded triplers inside, and was never able to isolate the diodes
from within the epoxy surroundings.
From my frustrated trials I got the impression they mount the multipliers
with the bare silicon PN pellets weld directly to the interconnecting
wires, and then they pour the epoxy all over so that, if you try to break
them free, you cannot tell the wires from the diodes in the middle of all
that epoxy.

But THAT! multiplier in the link you pointed out. That's AWSOME!

Brgrds,

Fabio

On May 31, 2017 7:37 PM, "Chuck Harris cfharris@... [TekScopes]" <
TekScopes@...> wrote:



I would presume that 3 of those "6 round capacitors"
were actually diodes.

Look up Cockroft-Walton Multiplier.

<https://en.wikipedia.org/wiki/Cockcroft-Walton_generator>

.....................................
.+--|(--+------+--|(--+-----> Voutput
.|......|......|......|..............
.A.....---.....v.....---.............
.C......^.....---.....^..............
.|......|......|......|..............
.+------+--|(--+------+..............
.|...................................
///..................................

Both HV rectifiers, and HV capacitors used to come
potted in round bakelite cylinders with axial leads.

-Chuck Harris


Samuel Rocha wrote:
Hi Group! I had just assembled again a new multiplier for the 465 scope
using:-six
BY8420- 24 kv, 3 mA diodes-six 1kpF / 6 kV capacitors.I filled with
acrylic resin

(used by dentists ) and then conected very fast to the multiplier, so I
heard a
noise inside the box, like a short circuit. Fortunately the HV was not
damaged, a
small horizontal trace is still on the screen. So I suppose that the
components
values above are all right, what may be the problem? Should I assembly
another
multiplier out of the box, using large spacings and HV wires to the scope
to see
if it works ? Now the mistery: I had dissablembled the original TEK
multiplier
152-0552-00 and I had found only six round capacitors but no diodes
inside the
plastic box! I am waititng for your suggestions and opinions,Regards to
all,Sam





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