This can physically handle 400V, but change the pass transistor for 1000V+
and change the FB resistors accordingly and poof! Perfect supply.

http://www3.telus.net/small_business/HVsupply.png

It's my design and I have releasd it under the Open Hardware License, so
go for it :-)

--
Gregg t3h g33k
"Ratings are for transistors....tubes have guidelines"
http://geek.scorpiorising.ca

Gregg wrote:

This can physically handle 400V, but change the pass transistor for 1000V+
and change the FB resistors accordingly and poof! Perfect supply.

http://www3.telus.net/small_business/HVsupply.png

It's my design and I have releasd it under the Open Hardware License, so
go for it :-)

--
Gregg t3h g33k
"Ratings are for transistors....tubes have guidelines"
http://geek.scorpiorising.ca

Gregg- Please show us how that circuit will deliver
300 ma over a range of +150 to +800 volts.

BTW, what is Open Hardware License?

There is nothing in your design that is original.

Cheers, John Stewart

VMI wrote:

Hi folks,I like to build a +150 to +800 V adjustable psu capable to
deliver 300 mA.Its use is for repair and setup experimental circuits.I
had enough of the trick with a variac.I prefer the ease of use of an
adjustable PSU.Any body out there with an idea or a
schematic?Thanks,Marco

If you are keen, you'd get a 500VA transformer wound
with a secondary suitable for use with a silicon bridge rectifier,
using 12 x IN5408 diodes arranged as a bridge with 3 diodes in series
for each of the four sides of the diode square of the bridge.

The HT sec should have a maximum voltage of 600 vrms,
with taps spaced at sixteen 35 volt intervals down from 600v to 75v.
This will give approximate 50 volt B+ steps.

There should be a CLC filter, using two 220 uF x 450v caps for C1,
L = 3 H @ 400 mA, and C2 = two 470 uF x 450v for C2.
If winding losses are below 7% the regulation should be OK for most
testing
without using a regulator containing tubes, and one which is able to be
adjustable over such a wide range of voltages.

If you had a 500 VA variac, there is no need for the taps on the tranny
sec,
and the B+ can be simply varied by turning the variac knob.

Changing the B+ by changing the connection of the bridge to the taps
means a really good switch must be used, and such switches are hard to
find
for 16 positions, or even more common 12 positions.
One could resolder a lead onto tranny terminals to change the B+,
but that's dangerous.
I try to avoid any switching of DC or DV, since arcing is all too
possible.

Patrick Turner.

John, you know that's impossible with that xfr! ... or is your question
intentionally loaded?
west

"John Stewart" wrote in message
...


Gregg wrote:

This can physically handle 400V, but change the pass transistor for
1000V+
and change the FB resistors accordingly and poof! Perfect supply.

http://www3.telus.net/small_business/HVsupply.png

It's my design and I have releasd it under the Open Hardware License, so
go for it :-)

--
Gregg t3h g33k
"Ratings are for transistors....tubes have guidelines"
http://geek.scorpiorising.ca

Gregg- Please show us how that circuit will deliver
300 ma over a range of +150 to +800 volts.

BTW, what is Open Hardware License?

There is nothing in your design that is original.

Cheers, John Stewart

west wrote:

John, you know that's impossible with that xfr! ... or is your question
intentionally loaded?
west

"John Stewart" wrote in message
...


Gregg wrote:

This can physically handle 400V, but change the pass transistor for
1000V+
and change the FB resistors accordingly and poof! Perfect supply.

http://www3.telus.net/small_business/HVsupply.png

It's my design and I have releasd it under the Open Hardware License, so
go for it :-)

--
Gregg t3h g33k
"Ratings are for transistors....tubes have guidelines"
http://geek.scorpiorising.ca

Gregg- Please show us how that circuit will deliver
300 ma over a range of +150 to +800 volts.

BTW, what is Open Hardware License?

There is nothing in your design that is original.

Cheers, John Stewart



Yes, it is well loaded. To often we see solutions given here & in
other forums which in some cases gravely mislead the uninformed.

Not only is the transformer anywhere near the task, but what about
the rest of the circuit? Should we believe a single FET as the losser
will be up to the job?

What about a heat sink(s)? How large should they be in order to
dissipate the heat resulting from the max current, minimum voltage
condition.

And the size of the filter caps please.
How about some calculations to illustrate where the
answers come from.

As shown the circuit is a very poor answer to the original query.

If I were marking this as part of a quiz in a Community College
environment, it would get a fail. BTW, I did spend 2 years
doing exactly that as part of my career path.

Anyway, still looking forward to Gregg's response.

Cheers, John Stewart

Behold, John Stewart signalled from keyed 4-1000A filament:


Anyway, still looking forward to Gregg's response.

Cheers, John Stewart

John,

Since when is offering help deserving of mock?

The circuit is a proven design and It is available commercially, from me.

You had a lot of respect from me until now.

Welcome to my BOZO file.

*plonk*

--
Gregg t3h g33k
"Ratings are for transistors....tubes have guidelines"
http://geek.scorpiorising.ca

Gregg wrote:

Behold, John Stewart signalled from keyed 4-1000A filament:

Anyway, still looking forward to Gregg's response.

Cheers, John Stewart

John,

Since when is offering help deserving of mock?

The circuit is a proven design and It is available commercially, from me.

You had a lot of respect from me until now.

Welcome to my BOZO file.

*plonk*

--
Gregg t3h g33k
"Ratings are for transistors....tubes have guidelines"
http://geek.scorpiorising.ca

The design I see posted at your link might manage 30 ma at 200-300
volts & that is on a good day. If we take into account your filter is
capacitor input then the supply is probably good for a realistic 25 ma.

All of that is a long, long way from what has been asked for.

If you are really able to come up with as simple solution as you have
offered then please let us see it.

Still don't know what an "Open Hardware License" is.
How can I apply for one? Do I need it?

Cheers, John Stewart

"John Stewart" wrote in message
...
Gregg wrote:
*plonk*

Since Gregggggg's being an a-hole I'll forward this message, but heck, I'll
reply to it at the same time, right here.

The design I see posted at your link might manage 30 ma at 200-300
volts & that is on a good day. If we take into account your filter is
capacitor input then the supply is probably good for a realistic 25 ma.

All of that is a long, long way from what has been asked for.

Well gee, it's obviously going to be scaled up. A lot.

I still wonder how the OP intends to get rid of the 200W of heat...

Either steps (seperate supplies, each say 150-250, 250-400, 400-600,
600-800V), or a nice variac as Pat(?) said, is definetly the order of the
day.

If you are really able to come up with as simple solution as you have
offered then please let us see it.

Still don't know what an "Open Hardware License" is.
How can I apply for one? Do I need it?

Cheers, John Stewart

It means you can modify his junk at will... a real-life development of his
*nix religion...

Tim (still on Win98 + IE/OE, still without viruses, still the same since I
came online 4 years ago. You *nix-ers still have no valid reason to
"convert" me with.)

--
"I've got more trophies than Wayne Gretsky and the Pope combined!"
- Homer Simpson
Website @ http://webpages.charter.net/dawill/tmoranwms

Seems to me the PS would need about all the available current just to
get the zener regulated emitter (reference) voltage 'stiff'. 15 volt
zeners instead of a single 47 volt unit would make the regulation
worse.. You have to hold that emitter voltage reasonably steady, else
it isn't really a regulator.

The time I worked out a SS feedback regulated PS, the challenges never
seemed to stop coming. Lots of blown pass transistors along the way.
This was from before the 3 terminal regulator device was available, the
reference regulator here isn't the best either and I recall discussing
adding a second zener at a higher voltage to stabilize the 13 volt one
as even this was susceptable to line voltage changes.


http://www2.arkansas.net/~jgsm/ss_psu.gif



Jeff Goldsmith

As far as I can understand, tubes provide a wide rangeability, but "wide" is
not infinite. 300 mA from 150 to 800 VDC means a dissipation in the series
pass element of ROUGHLY (800-150)*0.3=195W, ie. 6x 6AS7 or 3x 6S33S or 2x
13E1 in parallel...unless You resort to metal/ceramic "beasts" like a
3CX300. In any case it would be a really HUGE unit, and it would radiate as
much heat as an open oven.
To make it feasible in a some easier way, a "stepped" voltage at the series
regulator inlet is needed, ie. a HT transformer with at least two "taps" to
provide a dual-range system, say from 150 to 450V with the "low voltage"
feed and from 400 to 800V with the "high voltage" feed. I'd provide the HV
selector with some safety device to avoid "hot" switching.
Even better, two separate units could be made, in order to avoid troubles
(and an 800V trouble could be quite so...)
Mr. Steve Bench has written a lot about tube-regulated PS, You can "google"
for his page or just look at http://members.aol.com/sbench/reg1.html.
Somebody could say it can be done with silicon: indeed, I've seen sand-state
PS too, but I suppose that when it goes on mA and kV a tube is much more
fit-for-purpose; I just wouldn't ask that much from a single component.
There's a ton of schematics on-line, using many different toobs as
series-pass, from 6BM8 to 6AS7 to EL34 to KT66 to 6550 to EL509.........
just make Your choice.

Ciao

Fabio


"VMI" ha scritto nel messaggio
...
Well as you mentioned the use of multi position switches are hard to find
(not to talk about the price)
At the end they will fail and then...
A variac is a solution but (allthough I used it now) not the prefered one.
I had such a psu many years ago but I dumped it probably after changing
course to semicons.
So back to the box full with idea s coming from the readers of this forum.
I still have to have a look at the schem of John Stewart.
Thanks any way.

I see that such a HV PSU draws attention and can be the source of a long
debate.
Allthough many like to build such a supply, there isn't much around do
thinker with.
It is not as designing a psu for 50 or even 100 V DC.
More ideas are very welcome.

Marco