which diode for 55 Khz switching supply??

[Roger Gt]

"John Woodgate" wrote in message

Roger Gt wrote
snip

How dismally objective. Sloman Award, Class 3.

Would have been class 2 if you hadn't written 'KV' and 'Ma'.(;-)
--

If I cared, I would ask --
This from someone who drives on the wrong side of the road?
What the HELL is a "Sloman Award"? or are you (as Usual) just joking?

 

[John Woodgate]

I read in sci.electronics.design that Roger Gt <Xenot@pacbell.net> wrote
(in <B_JDb.72112$B64.20741@newssvr25.news.prodigy.com&gt about 'which
diode for 55 Khz switching supply??', on Tue, 16 Dec 2003:

"John Woodgate" wrote in message
Roger Gt wrote
snip

How dismally objective. Sloman Award, Class 3.

Would have been class 2 if you hadn't written 'KV' and 'Ma'.(;-)
--

If I cared, I would ask --
This from someone who drives on the wrong side of the road?

Only at Savoy Place.

What the HELL is a "Sloman Award"? or are you (as Usual) just joking?

If you don't care, I don't care to explain.

--
Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk
Interested in professional sound reinforcement and distribution? Then go to
http://www.isce.org.uk
PLEASE do NOT copy news posts to me by E-MAIL!

 

[Roger Gt]

"Roger Gt" <Xenot@pacbell.net> wrote in message
news:EkIDb.336$__7.8@newssvr27.news.prodigy.com...

Albert> wrote in message
news:n8gstvo715e3f156rpsdl8bpm3hbgh6age@4ax.com...


Later today perhaps, I need to get some work done too! My last serious
use
of spice was modeling all 14 boards in a weather satellite! Found many
interesting things in the circuits that no one expected!

I'm a spice newbee, got off to a bad start in spice by starting out
with crippleware though. I'm glad I didn't pay real money for the
program I started out with! I lost alot of time tho, because I
invested the time to learn how to run the crippleware! I shoulda just
started out with LTSpice in the first place!

Good luck to all.

A

Well. given the load you stated, and setting resistors on the first five
outputs to simulate that load. With a Square wave 50% duty cycle, 102V
55Khz, the outputs were 100.6 volts per step. To 1.066KV Note. Due to
the
loads variation from the low end.
The first four stages used 200nF caps, the rest (6) used 100nF caps. All
200V
I also switched to MA158 diodes. 200V, 100Ma, 1uA leakage.
The larger diodes work, but require more drive.
Input power in this form was about 1/2 watt.
Not as efficient as you were hoping for.

Revisited during lunch, I tried a Sine wave input. 37V at 55Khz. Input
current was only 12mA average. Much better! About the same voltages out.

 

[Roger Gt]

"John Woodgate" <jmw@jmwa.demon.contraspam.yuk> wrote in message
news:+FZKnFEu523$Ew7e@jmwa.demon.co.uk...

"Plonk" 30 days!

 

[Roger Gt]

"Roger Gt" wrote in message

"Roger Gt" wrote in message
Albert> wrote in message
snip
Well. given the load you stated, and setting resistors on the first
five
outputs to simulate that load. With a Square wave 50% duty cycle, 102V
55Khz, the outputs were 100.6 volts per step. To 1.066KV Note. Due to
the
loads variation from the low end.
The first four stages used 200nF caps, the rest (6) used 100nF caps. All
200V
I also switched to MA158 diodes. 200V, 100Ma, 1uA leakage.
The larger diodes work, but require more drive.
Input power in this form was about 1/2 watt.
Not as efficient as you were hoping for.

Revisited during lunch, I tried a Sine wave input. 37V at 55Khz. Input
current was only 12mA average. Much better! About the same voltages out.

..44 watts isn't bad! May be able to improve on it with time to play with
the values.

Also... I do not have the spice model for it, but a diode array MMBD2004S
looks a good choice and will cut the number of Diode packages in half.
I presume you have selected suitable capacitors, But I will list what I have
been using.... JIK

Top Magnetic

HVC0805Y5V104M200NT
HVC1206Y5V104M200NT

I prefer the 1206 for high voltage operation, but it's you pick so I
included both.
They also have 500, 1kV, and higher.

Contact information
TOP MAGNETICS CORPORATION

13925 Magnolia Avenue, Chino, California 91710

Tel: 909-590-8550 Fax: 909-590-8762

Website: www.topmagnetics.com Email: info@topmagnetics.com

 

[Jim Adney]

On Tue, 16 Dec 2003 00:23:21 -0500 Albert <> wrote:

I'm not sure the bias voltage sees the interelectrode capacitance
because it is pure (almost) dc, once the input to that dynode is
charged, it stays charged, it's dc.

You're right, that the output points are almost static in this
situation, but in every C-W there are 1 or 2 chains of caps which run
all the way to the top of the stack which have the full voltage swing
100% of the time. It is the capacitance between these chains and the
outside world AND the static, DC, part of the stack which causes the
parasitic current draw.

Even so, the actual C can't be more than a pf, and that cap is in
paralell with .1-.3 uF cap in the cw stage for that dynode. I just
can't imagine the losses being large::

Perhaps you're right, or maybe not. I'm really not too sure. I'm not
used to working at voltages or power levels this low, so my gut
feelings are a bit confused.

I would think the trr losses would be the major losses.

Could be. Too bad we can't buy 200V Shottkys.

-
-----------------------------------------------
Jim Adney jadney@vwtype3.org
Madison, WI 53711 USA
-----------------------------------------------

 

[Jim Adney]

On Tue, 16 Dec 2003 08:39:03 +0000 John Woodgate
<jmw@jmwa.demon.contraspam.yuk> wrote:

I read in sci.electronics.design that Mark Jones <127.0.0.1@?.?> wrote
(in <gr6dnS1DJ4xaNkOi4p2dnA@buckeye-express.com&gt about 'which diode for
55 Khz switching supply??', on Tue, 16 Dec 2003:
step-up
transformer --> multi-tapped toroidal step-up transformer --

These add cost, size and weight, especially the latter.

Not all that much if you did it at 55 kHz.

-
-----------------------------------------------
Jim Adney jadney@vwtype3.org
Madison, WI 53711 USA
-----------------------------------------------

 

[John Larkin]

On Tue, 16 Dec 2003 20:39:06 -0600, Jim Adney <jadney@vwtype3.org>
wrote:

Could be. Too bad we can't buy 200V Shottkys.

There are lots of 200 v schottkies around, but they tend to be big
puppies, so have a lot of junction capacitance and reverse leakage.
SiC parts are just becoming available, in the 400-600 volt range, with
prototypes at 1200 or so. Still, not suited for use in a low power
multiplier chain.

John

-
-----------------------------------------------
Jim Adney jadney@vwtype3.org
Madison, WI 53711 USA
-----------------------------------------------