| Author |
Message |
Peter Andersen
Guest
|
 Posted:
Sat Oct 22, 2005 2:40 am Post subject:
Designing a lab power supply for tube experimenting |
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Hi
I would very much like to have some ideas, schematics, tips on how to design
a lab power supply for experimenting with tube designs. The specifications
could be like 0-500V 0-100mA... (+/-?)
I would like to build a good regulated power supply. Could i just design it
like a normal low voltage PSU? like a opamp, voltagedivider, a BU508 as
seriesregulator, and a couple of high voltage caps.??
Please mail me any kind of schematics and give me some help and hints about
this project...
Peter
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Jon Yaeger
Guest
|
| Posted:
Sat Oct 22, 2005 2:50 am Post subject:
Re: Designing a lab power supply for tube experimenting |
|
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in article 43596055$0$171$edfadb0f@dtext02.news.tele.dk, Peter Andersen at
peterandersen@mespilus.dk wrote on 10/21/05 5:40 PM:
| Quote: | Hi
I would very much like to have some ideas, schematics, tips on how to design
a lab power supply for experimenting with tube designs. The specifications
could be like 0-500V 0-100mA... (+/-?)
I would like to build a good regulated power supply. Could i just design it
like a normal low voltage PSU? like a opamp, voltagedivider, a BU508 as
seriesregulator, and a couple of high voltage caps.??
Please mail me any kind of schematics and give me some help and hints about
this project...
Peter
|
Save yourself a lot of grief and buy a used Heath SP-17A power supply. I
saw one for sale for $50 here:
http://www-stlg.remote.arrl.org/RadiosOnline/ads.html?ordby=&wanted_category
=Power+Supplies
Or do the eBay thing.
Jon |
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Peter Andersen
Guest
|
| Posted:
Sat Oct 22, 2005 3:02 am Post subject:
Re: Designing a lab power supply for tube experimenting |
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I Jon
Yes, I have seen it a couple of times when I was browsing around the net,
but it is fun to make and design these things, and I have all the parts I
need for this kind of project.
I just want to read som experiences from others.
--
vh. Peter Andersen
www.mespilus.dk |
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Winfield Hill
Guest
|
| Posted:
Sat Oct 22, 2005 3:05 am Post subject:
Re: Designing a lab power supply for tube experimenting |
|
|
Peter Andersen wrote...
| Quote: |
I would very much like to have some ideas, schematics, tips on how
to design a lab power supply for experimenting with tube designs.
The specifications could be like 0-500V 0-100mA... (+/-?)
I would like to build a good regulated power supply. Could i just
design it like a normal low voltage PSU? like a opamp, voltagedivider,
a BU508 as seriesregulator, and a couple of high voltage caps.??
|
One problem in designing such a power supply is the short-circuit
current-limiting aspect of the design. BJT's have a horrible 2nd-
breakdown effect that will greatly exacerbate your design problems.
To get an idea of the problem, study the BU508's SOA curves. Ouch!
For example, at 40 volts, you're allowed 120 watts of dissipation,
but at 400V you're allowed only a wimpy 36 watts!!! These are 25C
values, which have to be derated as the transistor's case heats up.
I recommend that you use high-voltage MOSFETs as pass elements, and
avoid the issue.
--
Thanks,
- Win |
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Bret Ludwig
Guest
|
| Posted:
Sat Oct 22, 2005 3:11 am Post subject:
Re: Designing a lab power supply for tube experimenting |
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|
Jon Yaeger wrote:
<<snip>>
The Heathkit supply is nowhere near the quality of the Lambda and
Kepco supplies that are available just as cheaply. However, with
refurbishment, the Heathkit will do okay.
Glass Audio ran an article by Bruce Rozenblit on a very nice bench
supply you can build some time ago.
I prefer using a homebuilt HT supply which consists simply of a off
the shelf power transformer-mine is that of a Fisher receiver whose
OPTs went into Fender guitar amps-with diodes and caps I can just plug
into a Variac or into the wall for rated voltage, with nice recessed
test ports. I have a (shortable)light bulb socket in series with the
primary. I only use the HT winding, I use, and you should own, a
variable DC low voltage supply. Mine is a commercial Asian made one,
but older HP, Sorenson, Behlman Invar, Tek, or Lambda ones are hamfest
constants, or you can build one. Joe Carr has a good book with nice
plans. A Schauer or Schumacher garage sale battery charger can be
salvaged for a power xfmr and case.People throw them out all the time
when the leads are bad. |
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Peter Andersen
Guest
|
| Posted:
Sat Oct 22, 2005 3:28 am Post subject:
Re: Designing a lab power supply for tube experimenting |
|
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Bret Ludwig wrote:
| Quote: | The Heathkit supply is nowhere near the quality of the Lambda and
Kepco supplies that are available just as cheaply. However, with
refurbishment, the Heathkit will do okay.
Glass Audio ran an article by Bruce Rozenblit on a very nice bench
supply you can build some time ago.
|
Do you have a link, pdf, scan..? I would like to read it.
| Quote: | I prefer using a homebuilt HT supply which consists simply of a off
the shelf power transformer-mine is that of a Fisher receiver whose
OPTs went into Fender guitar amps-with diodes and caps I can just plug
into a Variac or into the wall for rated voltage, with nice recessed
test ports. I have a (shortable)light bulb socket in series with the
primary. I only use the HT winding, I use, and you should own, a
variable DC low voltage supply. Mine is a commercial Asian made one,
but older HP, Sorenson, Behlman Invar, Tek, or Lambda ones are hamfest
constants, or you can build one. Joe Carr has a good book with nice
plans. A Schauer or Schumacher garage sale battery charger can be
salvaged for a power xfmr and case.People throw them out all the time
when the leads are bad.
|
Hi
Yes, I have done this for some time, but now I want to make a real HV power
supply instead of the HV transformer/variac method. I have several HV
transformers from 500-2KV.
The real supply will of cause have a 6,3V output on the same box.
--
vh. Peter Andersen
www.mespilus.dk |
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John Fields
Guest
|
| Posted:
Sat Oct 22, 2005 3:43 am Post subject:
Re: Designing a lab power supply for tube experimenting |
|
|
On 21 Oct 2005 15:05:41 -0700, Winfield Hill
<Winfield_member@newsguy.com> wrote:
| Quote: | Peter Andersen wrote...
I would very much like to have some ideas, schematics, tips on how
to design a lab power supply for experimenting with tube designs.
The specifications could be like 0-500V 0-100mA... (+/-?)
I would like to build a good regulated power supply. Could i just
design it like a normal low voltage PSU? like a opamp, voltagedivider,
a BU508 as seriesregulator, and a couple of high voltage caps.??
One problem in designing such a power supply is the short-circuit
current-limiting aspect of the design. BJT's have a horrible 2nd-
breakdown effect that will greatly exacerbate your design problems.
To get an idea of the problem, study the BU508's SOA curves. Ouch!
For example, at 40 volts, you're allowed 120 watts of dissipation,
but at 400V you're allowed only a wimpy 36 watts!!! These are 25C
values, which have to be derated as the transistor's case heats up.
^^^^ |
junctions
| Quote: | I recommend that you use high-voltage MOSFETs as pass elements, and
avoid the issue.
|
--
John Fields
Professional Circuit Designer |
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Spehro Pefhany
Guest
|
| Posted:
Sat Oct 22, 2005 3:59 am Post subject:
Re: Designing a lab power supply for tube experimenting |
|
|
On Fri, 21 Oct 2005 17:43:36 -0500, the renowned John Fields
<jfields@austininstruments.com> wrote:
| Quote: | On 21 Oct 2005 15:05:41 -0700, Winfield Hill
Winfield_member@newsguy.com> wrote:
Peter Andersen wrote...
I would very much like to have some ideas, schematics, tips on how
to design a lab power supply for experimenting with tube designs.
The specifications could be like 0-500V 0-100mA... (+/-?)
I would like to build a good regulated power supply. Could i just
design it like a normal low voltage PSU? like a opamp, voltagedivider,
a BU508 as seriesregulator, and a couple of high voltage caps.??
One problem in designing such a power supply is the short-circuit
current-limiting aspect of the design. BJT's have a horrible 2nd-
breakdown effect that will greatly exacerbate your design problems.
To get an idea of the problem, study the BU508's SOA curves. Ouch!
For example, at 40 volts, you're allowed 120 watts of dissipation,
but at 400V you're allowed only a wimpy 36 watts!!! These are 25C
values, which have to be derated as the transistor's case heats up.
^^^^
junctions
I recommend that you use high-voltage MOSFETs as pass elements, and
avoid the issue.
|
Cat got your tongue?
Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com |
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|
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Pooh Bear
Guest
|
| Posted:
Sat Oct 22, 2005 4:03 am Post subject:
Re: Designing a lab power supply for tube experimenting |
|
|
Spehro Pefhany wrote:
| Quote: | On Fri, 21 Oct 2005 17:43:36 -0500, the renowned John Fields
jfields@austininstruments.com> wrote:
On 21 Oct 2005 15:05:41 -0700, Winfield Hill
Winfield_member@newsguy.com> wrote:
Peter Andersen wrote...
I would very much like to have some ideas, schematics, tips on how
to design a lab power supply for experimenting with tube designs.
The specifications could be like 0-500V 0-100mA... (+/-?)
I would like to build a good regulated power supply. Could i just
design it like a normal low voltage PSU? like a opamp, voltagedivider,
a BU508 as seriesregulator, and a couple of high voltage caps.??
One problem in designing such a power supply is the short-circuit
current-limiting aspect of the design. BJT's have a horrible 2nd-
breakdown effect that will greatly exacerbate your design problems.
To get an idea of the problem, study the BU508's SOA curves. Ouch!
For example, at 40 volts, you're allowed 120 watts of dissipation,
but at 400V you're allowed only a wimpy 36 watts!!! These are 25C
values, which have to be derated as the transistor's case heats up.
^^^^
junctions
I recommend that you use high-voltage MOSFETs as pass elements, and
avoid the issue.
Cat got your tongue?
|
It puzzled me too at first
Look for the up arrows under the word case ( although it may have moved now on
account of the fixed/proportional spacing issue )
Graham |
|
| Back to top |
|
|
Bret Ludwig
Guest
|
| Posted:
Sat Oct 22, 2005 4:43 am Post subject:
Re: Designing a lab power supply for tube experimenting |
|
|
Peter Andersen wrote:
| Quote: | Bret Ludwig wrote:
The Heathkit supply is nowhere near the quality of the Lambda and
Kepco supplies that are available just as cheaply. However, with
refurbishment, the Heathkit will do okay.
Glass Audio ran an article by Bruce Rozenblit on a very nice bench
supply you can build some time ago.
Do you have a link, pdf, scan..? I would like to read it.
I prefer using a homebuilt HT supply which consists simply of a off
the shelf power transformer-mine is that of a Fisher receiver whose
OPTs went into Fender guitar amps-with diodes and caps I can just plug
into a Variac or into the wall for rated voltage, with nice recessed
test ports. I have a (shortable)light bulb socket in series with the
primary. I only use the HT winding, I use, and you should own, a
variable DC low voltage supply. Mine is a commercial Asian made one,
but older HP, Sorenson, Behlman Invar, Tek, or Lambda ones are hamfest
constants, or you can build one. Joe Carr has a good book with nice
plans. A Schauer or Schumacher garage sale battery charger can be
salvaged for a power xfmr and case.People throw them out all the time
when the leads are bad.
Hi
Yes, I have done this for some time, but now I want to make a real HV power
supply instead of the HV transformer/variac method. I have several HV
transformers from 500-2KV.
The real supply will of cause have a 6,3V output on the same box.
|
The article is the property of AudioXPress but you might email Bruce
Rozenblit, who might be able to get you a copy. |
|
| Back to top |
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west
Guest
|
| Posted:
Sat Oct 22, 2005 11:51 am Post subject:
Re: Designing a lab power supply for tube experimenting |
|
|
"Bret Ludwig" <bretldwig@yahoo.com> wrote in message
news:1129942897.929549.93690@o13g2000cwo.googlegroups.com...
| Quote: |
Peter Andersen wrote:
Bret Ludwig wrote:
The Heathkit supply is nowhere near the quality of the Lambda and
Kepco supplies that are available just as cheaply. However, with
refurbishment, the Heathkit will do okay.
Glass Audio ran an article by Bruce Rozenblit on a very nice bench
supply you can build some time ago.
Do you have a link, pdf, scan..? I would like to read it.
|
Me too, Bret. Do you recall the year & month of that Glass Audio article?
west |
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| Back to top |
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west
Guest
|
| Posted:
Sat Oct 22, 2005 11:51 am Post subject:
Re: Designing a lab power supply for tube experimenting |
|
|
"Bret Ludwig" <bretldwig@yahoo.com> wrote in message
news:1129942897.929549.93690@o13g2000cwo.googlegroups.com...
| Quote: |
Peter Andersen wrote:
Bret Ludwig wrote:
The Heathkit supply is nowhere near the quality of the Lambda and
Kepco supplies that are available just as cheaply. However, with
refurbishment, the Heathkit will do okay.
Glass Audio ran an article by Bruce Rozenblit on a very nice bench
supply you can build some time ago.
Do you have a link, pdf, scan..? I would like to read it.
|
Me too, Bret. Do you recall the year & month of that Glass Audio article?
west
<snip> |
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| Back to top |
|
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west
Guest
|
| Posted:
Sat Oct 22, 2005 11:55 am Post subject:
Re: Designing a lab power supply for tube experimenting |
|
|
"Jon Yaeger" <jono_1@bellsouth.net> wrote in message
news:BF7EDAD7.3C46C%jono_1@bellsouth.net...
| Quote: |
in article 43596055$0$171$edfadb0f@dtext02.news.tele.dk, Peter Andersen at
peterandersen@mespilus.dk wrote on 10/21/05 5:40 PM:
Hi
I would very much like to have some ideas, schematics, tips on how to
design
a lab power supply for experimenting with tube designs. The
specifications
could be like 0-500V 0-100mA... (+/-?)
I would like to build a good regulated power supply. Could i just design
it
like a normal low voltage PSU? like a opamp, voltagedivider, a BU508 as
seriesregulator, and a couple of high voltage caps.??
Please mail me any kind of schematics and give me some help and hints
about
this project...
Peter
Save yourself a lot of grief and buy a used Heath SP-17A power supply. I
saw one for sale for $50 here:
http://www-stlg.remote.arrl.org/RadiosOnline/ads.html?ordby=&wanted_category
=Power+Supplies
Or do the eBay thing.
Jon
Jon, |
Do you think a 100ma HT supply will be adequate?
west |
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| Back to top |
|
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Fred Bartoli
Guest
|
| Posted:
Sat Oct 22, 2005 1:56 pm Post subject:
Re: Designing a lab power supply for tube experimenting |
|
|
"Pooh Bear" <rabbitsfriendsandrelations@hotmail.com> a écrit dans le message
de news:435973D6.D4F4E4C3@hotmail.com...
| Quote: |
Spehro Pefhany wrote:
On Fri, 21 Oct 2005 17:43:36 -0500, the renowned John Fields
jfields@austininstruments.com> wrote:
On 21 Oct 2005 15:05:41 -0700, Winfield Hill
Winfield_member@newsguy.com> wrote:
Peter Andersen wrote...
I would very much like to have some ideas, schematics, tips on how
to design a lab power supply for experimenting with tube designs.
The specifications could be like 0-500V 0-100mA... (+/-?)
I would like to build a good regulated power supply. Could i just
design it like a normal low voltage PSU? like a opamp,
voltagedivider,
a BU508 as seriesregulator, and a couple of high voltage caps.??
One problem in designing such a power supply is the short-circuit
current-limiting aspect of the design. BJT's have a horrible 2nd-
breakdown effect that will greatly exacerbate your design problems.
To get an idea of the problem, study the BU508's SOA curves. Ouch!
For example, at 40 volts, you're allowed 120 watts of dissipation,
but at 400V you're allowed only a wimpy 36 watts!!! These are 25C
values, which have to be derated as the transistor's case heats up.
^^^^
junctions
I recommend that you use high-voltage MOSFETs as pass elements, and
avoid the issue.
Cat got your tongue?
It puzzled me too at first
Look for the up arrows under the word case ( although it may have moved
now on
account of the fixed/proportional spacing issue )
|
Plus it's plain wrong. The max power dissipation depends on the case
temperature. If the junction was at 25°C there will be no power limit.
--
Thanks,
Fred. |
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| Back to top |
|
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Ken Smith
Guest
|
| Posted:
Sat Oct 22, 2005 5:04 pm Post subject:
Re: Designing a lab power supply for tube experimenting |
|
|
In article <djbonl01cbp@drn.newsguy.com>,
Winfield Hill <Winfield_member@newsguy.com> wrote:
[....]
| Quote: | One problem in designing such a power supply is the short-circuit
current-limiting aspect of the design. BJT's have a horrible 2nd-
breakdown effect that will greatly exacerbate your design problems.
|
A type 861 triode doesn't have a 2nd breakdown problem.
| Quote: | I recommend that you use high-voltage MOSFETs as pass elements, and
avoid the issue.
|
With care, you can float all the smarts of the regulator circuit at the
source voltage of the FET. Since this is mains powered, a very small
transformer can be used to make a floating 12V to run the regulator
circuit.
High V
!
!!-
Gate----------!!-
!!-
!
I sense --------+
!
/
\
/
\ Vfloat
------------------------+---------------- To load
----------------------------------------- GND
******************
VRef -/\/\-----+-->!--- overcurrent/
!
!
!
!
GND -/\/\/\/--+-!+\
! >----+-/\/\/-+--- Gate
--!-/ ! !
! ! V
+-/\/\--!!- ---
! !
\ Over Current/
/
\
/
!
Vfloat
*************************
-------+----------- Over current/
!/ c !
ISense ---+---------------! !
! !\ e !
! ! !
! Vref2 !
! -\/\/--!!--------+
! ! !
-/\/\-+--!-\ !
! >-----------
Vref2--!+/
--
--
kensmith@rahul.net forging knowledge |
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