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Re: Fullwave rectifier
Subject: Re: Fullwave rectifier
Date: Sun, 18 May 1997 10:54:15 -0400 (EDT)
From: FutureT-at-aol-dot-com
To: tesla-at-pupman-dot-com
> I am going to be working on modulating the output of my Tube coil, and
> am curently working on designing a filtered DC supply from a Microwave
> oven Trany. My first step will be to make the fullwave rectifier. As, I
> am not an EE and have not much training in the field (I work in the area
> of Radiation Health Physics sciences), I have some very basic questions
> regarding diodes in general. First, as HV, High current diodes are not
> the easyest things to obtain, what are the ramifications of series
> implementation of lower voltage for higher voltage? Perhaps, I am a bit
> to familiar with Capacitors and am getting confused? Second, well, if I
> am going to need to find a supplier of HV Diodes, does anyone on this
> list have any sugestions? About one Kilovolt AC at 35 Amps has been the
> highest I'v seen recently. Any help is more than welcome. Thanks,
> David Trimmell
>>
David,
I would just use cheap and readily available 1N4007 rectifiers, about 5
of
them in series in each leg of the bridge (20 diodes in total). Place
both a
.01uF cap, and a 370k resistor across each rectifier diode to "take care
of"
variations in the diodes. These diodes are rated at 1kV at 1 amp (or
is it
2.5A - I forget). In any case they can take the abuse, you don't need a
35
amp rating or anything that robust. I use the 1N4007 rectifiers in all
my DC
coils; tube coils, staccato (pulsed) tube coils, steady disruptive DC
coils,
pulsed DC disruptive coils, etc. up to 20 kV at 6000 VA. These higher
voltage systems used over 100 diodes in the bridge. I've never had a
diode
failure despite the fearsome kickback of pulsed coil operation. It is
important to use protective chokes and RF bypass caps, although the
filter
cap helps to absorb some of the kickback also.
Have fun and be safe,
John Freau