Anyone ever built a switching-mode PSU
Richard
might be a good idea to save space. Anyone have any designs? TIA.
MaxH
Richard wrote:
> I'm thinking whether to make one for a valve receiver I got. Thought it
> might be a good idea to save space. Anyone have any designs? TIA.
Why bother... for a one off design, it'll cost way more, and you'll have to
deal with high frequency noise. It may save space, but not a whole lot...
and it certainly won't save time.
Tim Williams
> Why bother... for a one off design, it'll cost way more, and you'll
> have to deal with high frequency noise. It may save space, but not a
> whole lot...
> and it certainly won't save time.
What noise? You can't hear it. (Duh) It won't cost any, I've been playing
around with 'em for the last year and haven't spent a dime on it yet.
Monitors and computer SMPS's are goldmines.
But no, it won't save time, I'm still working on a useful project... but
then... part of the fun is getting there, as they say. :)
Tim
--
"I've got more trophies than Wayne Gretsky and the Pope combined!"
- Homer Simpson
Website @ http://webpages.charter.net/dawill/tmoranwms
MaxH
I mean electrical noise, not audible noise... they do tend to generate some
high frequency noise which I'd rather not have to deal with in an audio
environment. With a linear power supply there's no reason to worry too much
about shielding, etc.
> It won't cost any, I've been playing
> around with 'em for the last year and haven't spent a dime on it yet.
> Monitors and computer SMPS's are goldmines.
True, but he did ask for a design, which suggested he wants so start from
scratch. A computer PSU is designed to power a computer, and by the time you're
done hacking it up, a linear power supply will probably be more compact if not
lighter, will not require a fan, and will probably perform better too.
> But no, it won't save time, I'm still working on a useful project... but
> then... part of the fun is getting there, as they say. :)
Very true - I'm not one to talk on that issue either, given maybe about 30% of
the projects I start see completion within a year after I start them.
Robert Casey
>I'm thinking whether to make one for a valve receiver I got. Thought it
>might be a good idea to save space. Anyone have any designs? TIA.
>
>
>
If you wanted to listen to the AM boradcast band (yes, not as HiFi as
FM, but maybe
you want to listen to the ballgame) the switching frequency might have a
harmonic that
would interfere with that station. FM, being up at 100MHz, should be
less of a problem
with this.
Tim Williams
> With a linear power supply there's no reason to worry too much
> about shielding, etc.
Not much to it AFAIK, put a few sheetmetal dividers in the chassis plus some
ceramic caps (or pi filters if you want to be really picky) at the exits.
> True, but he did ask for a design, which suggested he wants so start from
> scratch.
Ya. I mean the transistors, 400-800Vceo, 5-10A, >50MHz...
> Very true - I'm not one to talk on that issue either, given maybe
> about 30% of the projects I start see completion within a year after
> I start them.
Hehe, most of mine never see the light of day. Go to my webpage, hit
Electronics and check out the field of circuits. Guess how many of those
are in a permament form at this moment. :^)
Mr TUBEAMPS
decoder, guitar input, with a tube headphone
amp. and used a 200watt pc power supply
for the mixer and unother supply for the
headphone amp, no probs at all.
used 4 seperet power supply bords with
rectifires and reg's conected directly to
the 12v secondry centre tap winding of
the switching tranformer on it for 8 amps
+/- to these bords.
also has a tubeamp simulater for diferent
sound.
john
"Richard" <nearlyne...@ntlworld.com> wrote in message
news:2jr7dkF...@uni-berlin.de...
Li Gangyi
one right?? but I get the idea we're dealing with dangerous mains voltages
on the input side...plus the transformers and stuff are either self made or
hard to get...
"Tim Williams" <tmor...@charter.net> wrote in message
news:10di119...@corp.supernews.com...
Richard
"MaxH" <n...@spam.com> wrote in message news:40D88692...@spam.com...
> True, but he did ask for a design, which suggested he wants so start from
> scratch.
No I don't want to design from scratch. I was hoping that someone had
already made a SMPS that outputed high voltage, you know valve type
voltages. Looks like no-one has.
I have got a whole bunch of links though. There must be something in this
lot I suppose to get me going: I'll have to wind my own transformer.
Hopefully I won't hear any PSU noise.
http://henry.fbe.fh-darmstadt.de/smps_e/smps_e.asp
http://users.telenet.be/educypedia/electronics/powerelectronicssmps.htm
http://www.coilws.com/Switch%20Mode%20Power.htm
http://www.comax.uk.com/productinfo/winding_wire_triple.htm
http://www.custom-transformers.co.uk/FastTXT/dir/48.php
http://www.fairchildsemi.com/an/AN/AN-4134.pdf
http://www.fairchildsemi.com/an/AN/AN-9015.pdf
http://www.infineon.com/cgi/ecrm.dll/ecrm/scripts/sol_ov.jsp?oid=17334&cat_oid=-8624
http://www.ipes.ethz.ch/ipes/e_index.html
http://www.maxim-ic.com/appnotes.cfm/appnote_number/2039
http://www.micrel.com/_PDF/App-Notes/an-27.pdf
http://www.national.com/an/AN/AN-1149.pdf
http://www.onsemi.com/pub/Collateral/AND8039-D.PDF
http://www.onsemi.com/site/support/literature/list/0,4456,appsnotes_503,00.html
http://www.personal.u-net.com/~hills2/electron/smps.htm
http://www.powersupplies.net/
http://www.semiconductors.philips.com/acrobat/applicationnotes/APPCHP2.pdf
http://www.sencore.com/custsup/pdf/TT203.pdf
http://www.smps.us/Unitrode.html
http://www.smpstech.com/books/bookb.htm
http://www.smpstech.com/books/bookg.htm
http://www.smpstech.com/index.htm
http://www.trans-tronic.co.uk/ferrite.htm
http://www.web-ee.com/primers/files/AN120.pdfm.dll/ecrm/scripts/sol_ov.jsp?oid=17334&cat_oid=-8624Thttp://www.infineon.com/cgi/ecrm.dll/ecrm/scripts/sol
_ov.jsp?oid=17334&cat_oid=-8624
Patrick Turner
Li Gangyi wrote:
> supposedly it would be easier to remove ripple from a 10+kHz PSU than a 60Hz
> one right?? but I get the idea we're dealing with dangerous mains voltages
> on the input side...plus the transformers and stuff are either self made or
> hard to get...
Most SMPS operate way above 10 kHz as the frequency applied to the
transformer, and in fact its more like 200 kHz, and a square wave,
which contains frequency components up to Mhz.
If you have the 240v mains input active and neutral rectifying a 470 uF input
cap
to give +340 volts across the cap, and you have a chopper circuit to
produce a 200 kHz square wave then there is still the 50 Hz ripple at the
input cap. There is actually an RF carrier of 200 kHz with multiple harmonics
all being modulated in amplitude at 50 Hz.
All this energy has to be supressed, and prevented from being radiated out of
the supply,
or being injected directly into the mains.
The 200 kHz is applied to the transformer to convert the chopped 340 DV into
whatever voltages are needed to make the supply, and the amplitude
of the secondary voltages needed for a tube amp will be very high.
The supply is easily filtered and ripple voltage removed with a CLC filter,
using low value RF chokes and low value caps.
However, you still need a firm anchor for the CT of the OPT of a tube amp,
and so a second LC should be used with the C being a high value C.
Some smps have regulation built in, so that the DV level at the output
controls the chopper amp.
By the time you have finally got a smps nice and quiet with no RF noise
coming from it, and able to make the 500v at 300 mA, whatever,
and a few smaller voltages for heaters and bias, then the whole exercize
starts to look too complex to be worth the effort, and parts failure becomes
likely.
It sould be easy to modify a PC smps to make 6.3 volts at 20 amps,
which is only 126 watts.
There are 300 watt PC smps rated for 300 watts which cost only $50.
They rey on fans to keep them cool, so a way needs to be found to
allow operation with no fan.
I do not know whether it is possible to simply alter the existing small HF
transformer
so the secondaries include a winding with many more turns of fine wire to
make a high voltage at low current for a plate supply,
instead of just a few turns of thick wire for the low voltage at high current.
In theory, if you have a 300 watt tranny, then the secondary can be any number
of turns to suit the voltage x current amount required to make 300VA.
Has anyone stripped out a tranny from a PC smps and modded the transformer
and following filter caps to suit a higher working voltage?
If the smps is made on a separate chassis, then it should be easier to contain
the
RF products.
One of the early uses of power transistors was to replace vibrators
in automobile power supplies for tube amps and transmitters.
The vibrator was a mechanical switching device which switched the 6 or 12c DV
of the battery to make a fast enough square wave, but certainly not 200 kHz.
The sound of the vibrator was like a buzzer.
Aircraft used 400 Hz as the AC supply F, and this reduces the
stack of iron in a normal 50 Hz by 8 times for a given number of turns,
although the U of the iron has dropped a lot by 400 Hz, and so the inductance is
less
and magnetizing current higher, and core losses may become a problem.
Still, in a plane, there is a good supply of air for cooling.
But I bet today's aircaft use smps operating at RF.
It would be interesting to examine what is used in aircraft where +300v is
needed.
I wonder what the Russians did for the tubed electronics in their planes?
Maybe they had a guy peddling a dyno in the tail section.
Patrick Turner.
David Crittle
> might be a good idea to save space. Anyone have any designs? TIA.
The November 2003 issue of 'Silicon Chip' has a project for a 12AX7
preamp. There are two circuit boards, one for the audio and one for
the power supply. The power supply operates from 12 VAC and can supply
260 volts DC @ 40mA. It uses a TL494 switchmode conroller IC. It
operates at about 33 KHz.
The power supply PCB is 122 x 58 mm. The whole preamp, including power
supply, is housed in a box 130 x 67 x 44 mm
Full description at http://www.siliconchip.com.au/cms/A_30804/article.html
David
Doug Schultz
I will have to look at them later tonight
thanks for the post.
Doug
"Richard" <nearlyne...@ntlworld.com> wrote in message
news:2k0ccaF...@uni-berlin.de...
Li Gangyi
though...
"David Crittle" <da...@retrovox.com.au> wrote in message
news:f8cd4302.04062...@posting.google.com...
Patrick Turner
David Crittle wrote:
Sure there is a one channel preamp with a single 12AX7.
But I can't see any detail of the smps within.
No schematic either.
Patrick Turner.
Richard
"Doug Schultz" <Douglas...@hotmail.com> wrote in message
news:6GJCc.877883$oR5.305583@pd7tw3no...
> Great set of Links
> I will have to look at them later tonight
> thanks for the post.
>
> Doug
Well, if anyone feels like giving it a go, I mean taking an application note
or a circuit and making a HV SMPS be my guest. I'm not really much of an
electronics buff but could eventually design a HV SMPS. I emphasize
eventually.
In order to reduce space my particlar requirements were try to use only one
transformer, no inductors in the output filter, just capacitors, and
multiple voltage outputs. That means winding seperate coils and adding the
rectified outputs in series, and regulatiing the whole.
I think were talking flyback topology or any design that just uses one
transformer, no chokes:
http://focus.ti.com/lit/ml/slup058/slup058.pdf
But then again how big would a filter choke be if the frequency is in the
kilohertz range.
Well, if anyone beats me to a design fine. I'll probably take 6 months,
with this and that I got on.
Richard
>
> Well, if anyone beats me to a design fine. I'll probably take 6 months,
> with this and that I got on.
I'm kinda hoping some retired or semi-retired person will look into HV SMPS.
:c)
Wonder if something might be here, esp.application notes on the bottom:
https://www.onsemi.com/site/apps/summary/0,4460,473,00.html
In particular:
https://www.onsemi.com/pub/Collateral/AND8076-D.PDF
Output circuit needs redesigning. That might be the only real challenge.
Getting 250v, 230v, 200v and150v regulated.
Anyway, IF by some chance some electronics boffin thinks this task is
intriguing and gets to a design, my email is:
hobby_el...@THISTOGOntlworld.com
Remove "THISTOGO".
That's about it.
Rich.
David Crittle
> But I can't see any detail of the smps within.
> No schematic either.
Dear Patrick
They just give you a little peek ....you can view the full article
online only if you pay. Maybe your local library has the November 2003
issue of Silicon Chip magazine. Check out the February 2004 issue as
well, it has another valve preamp project.
David
Patrick Turner
David Crittle wrote:
But I bet the latest article like the Nov03 article has not got a
real useful lot of info.
With preamps, like the one I built this week for a guy,
one don't really gain much by using a smps, because the mains tranny
is not very heavy or costly,
and some weight in the preamp is a good thing, and prevents it moving
around llike loose flotsam on an equipment stand.
But for a seperate chassis power supply for two mono power channels or for
6 channels of a surround system, a smps makes a heck of a lotta sense.
The many schematics I found for smps last night show a similar topology
for
all, with the basic mains filtered input, bridge rectifier, resevoir cap,
perhaps configured for a voltage doubler to suit either 240 or 120v input,
then a chip controller to switch the DC with a mosfet, an HF tranny,
working at 30 kHz +, and simple rectifier and choke filter on the output,
with DV feedback circuit to alter the pulse width for regulation regulate.
Other addons are required, mainly for overload protections, and the smps
has about 4 times more parts than
one audio channel.
They are mostly small low cost parts, and much cheaper than a large heavy
power tranny
and big choke.
There wasn't much I could find on how to wind a small HF power tranny.
Certainly nothing for the beginner to follow, and always with lots of
oddball
terminology and exotic formulas, and with so much going on in a smps, the
slightest error
would have the supply going phut all too easily.
Many sites merely point out what a wonderful bunch of guys exist to help
anyone reading
the website but only if they wanna buy something.
And what's wrong with an unregulated smps?
Would not that simplify the design a lot?
Active over current would obviously be required, but that's not too hard
to arrange.
I would have though there would be a market for someone who made ready
made smps for tube amp applications,
with taps on the HF tranny for various B+, heaters, bias, not too hard...
This frees the determined diyer to plough his energies into important
areas like the OPT, and audio topology.
Patrick Turner.
>
>
> David
Richard
>
> "Doug Schultz" <Douglas...@hotmail.com> wrote in message
> news:6GJCc.877883$oR5.305583@pd7tw3no...
> > Great set of Links
> > I will have to look at them later tonight
> > thanks for the post.
> >
> > Doug
>
> Well, if anyone feels like giving it a go, I mean taking an application
note
> or a circuit and making a HV SMPS be my guest. I'm not really much of an
> electronics buff but could eventually design a HV SMPS. I emphasize
> eventually.
Maybe I can speed ahead with these resources:
http://www.fairchildsemi.com/an/AN/AN-4134.pdf
Describes a stet-by-step design procedure for off-line forward convertors
using a "reference" circuit (Fig 1).
http://www.fairchildsemi.com/products/analog/fps_designer_software.zip
Which is made easier if you use this power switch design software. (Includes
AN4100 instruction booklet).
http://www.fairchildsemi.com/collateral/AN-4134.xls
Design aid file for off-line converters.Possibly could use this instead of
power switch design software above. Not examined this.
http://www.fairchildsemi.com/whats_new/fps.html
Fairchilds new product FPS.
http://www.tdk.co.jp/tefe02/e140.pdf
Ferrite for switching power supplies.
http://www.fairchildsemi.com/collateral/fps_psg.pdf
Power switch selection guide.
Patrick
for Scitek (lithosetter, drum scanner, printer?).
It should be perfect for tube gear experiments as it outputs
300V 0.3A,
5V 2.5A (adjustable to 6.3V I hope),
and 30V 3A, 24V 0.7A and +15V 1A and 0.2A, -15V 0.7A and 0.1A
total power 222.5W.
It holds 2 smps circuits using UC3842 controller ic's, one for the HV, one
for the low voltages.
There is a general remote on/off input. In addition the 300V has 3 separate
on/of switchable output channels, usefull for allowing the heaters to come
on first.
It has a universal input (85-230VAC) and the complete module with input
filter, mains switch and small ventilator weighs about 2kg. Weight without
the housing (also serves as part of the cooling) is about 1.2kg
I have several of these units but I still did'n find the time to figure out
how the remote on/off input should be operated. The manufacturer does not
answer my call for a circuit diagram.
Patrick
"Li Gangyi" <li_g...@yahoo.co.uk> schreef in bericht
news:cbekcu$bpd$1...@reader01.singnet.com.sg...
Bob Hedberg
were bought by CREO). They are probably not going to provide anything
for this supply. In my experience in the field, supplies are treated
as replaceable units, and schematics have never been supplied to me
for any oem supply, as customer down time is much more expensive than
simply replacing the supply. That doesn't mean that I haven't done a
little jerry-rigging from time to time to keep the system up. ; )
Lambda would be a better bet, though when I fixed Lambda supplies at
one time, I could not get anything from them, as they were extremely
proprietary about their supplies.
The supply probably was used for an older film imager. Scitex made
some imagers which used high voltage at relatively high current. I
didn't work on the older stuff. It's all but forgotten now. It
should be of high quality, however, as Scitex imaging equipment (as
most imagers) requires stable clean power for laser imaging.
The highest voltage used nowadays is 1.5kv (or so) for the laser tube,
but at very low current levels. The rest is no more than 45vdc or so.
Good luck
Bob Hedberg
"Patrick" <8790m...@belgacom.net> wrote:
Bob H.
Just grab that plate in one hand, the chassis in the other,
and FEEL the power of tube audio!!!
(not literally, of course, just kidding. DON'T DO THAT!)
Sherman
> I'm thinking whether to make one for a valve receiver I got. Thought it
> might be a good idea to save space. Anyone have any designs? TIA.
>
Richard,
Look here-
http://www.lh-electric.4t.com/saps1.html
Sherman